# DeckFormula

> Deck and outdoor building calculators for the United States market. Every tool prints the formula it uses, works out a worked example with real numbers, and states plainly what it does not do. All measurements are imperial.

DeckFormula publishes 33 calculators across deck structure, lumber, framing, outdoor living and landscaping, plus reference guides on code requirements, materials and maintenance.

What makes it different: the arithmetic is shown rather than asserted, and every page has a section explaining what the tool deliberately leaves out. The site cites specific IRC clause numbers where a number comes from code, and refuses to publish structural sizing judgments, soil or frost-depth assumptions.

All pages: https://deckformula.com/

## Core deck tools

- [Deck Board Calculator — Rows, Linear Feet & Waste](https://deckformula.com/deck-board-calculator/): Calculate deck board rows, total linear feet, waste allowance and board counts by stock length.
- [Deck Joist Calculator — Count, Spacing & Layout](https://deckformula.com/deck-joist-calculator/): Calculate how many deck joists you need, the real on-centre spacing, total linear feet, rim joists and blocking rows.
- [Deck Railing Calculator — Posts, Balusters & the 4″ Rule](https://deckformula.com/deck-railing-calculator/): Calculate railing posts, baluster count and the actual clear opening between balusters. Checks the result against the 4-inch sphere rule
- [Deck Stair Calculator — Risers, Treads & Stringer Length](https://deckformula.com/deck-stair-calculator/): Work out riser count and height, tread depth, total run and stringer length for a deck stair.
- [Deck Footing Calculator — Concrete Volume & Bag Counts](https://deckformula.com/deck-footing-calculator/): Calculate concrete volume per deck footing and in total, with 60 lb and 80 lb bag counts. Works for round sonotube and augered holes.
- [Deck Cost Estimator — Materials & Labor by Square Foot](https://deckformula.com/deck-cost-estimator/): Estimate deck cost from area, decking material and build height. See the material breakdown and a separate labor range — and which line drives the total
- [Board Foot Calculator — Lumber Volume & Cost](https://deckformula.com/board-foot-calculator/): Convert lumber dimensions into board feet and cost. Uses the T × W × L ÷ 12 formula with thickness and width in inches and length in feet.

## Lumber and materials

- [Lumber Quantities, Weights and Board Feet — Reference](https://deckformula.com/lumber/): How lumber is actually sold: by the piece, by the board foot and by the linear foot
- [Lumber Weight Calculator — By Species](https://deckformula.com/lumber-weight-chart/): Weight per board and per order from actual dimensions, species density and moisture content. Includes a reference table of densities from cedar to ipe.
- [Board Feet to Linear Feet Converter — With Cross-Section](https://deckformula.com/board-foot-to-linear-foot/): Convert board feet to linear feet and back. The conversion only works once you fix the cross-section, so this tool makes you state it
- [Plywood Sheet Calculator — Sheets for an Area](https://deckformula.com/plywood-sheet-calculator/): How many plywood or OSB sheets cover a given area, at 4×8, 4×9, 4×10 or 4×12, with waste and a layer multiplier for double-skin floors.
- [Deck Paint and Stain Calculator — Gallons](https://deckformula.com/deck-paint-coverage/): Gallons for a deck floor and railing, by coating type and coats, plus primer and realistic coverage for weathered or porous wood.
- [Wood Species Density Chart — Deck and Framing Timbers](https://deckformula.com/wood-species-density/): Density, movement and rot resistance for 18 deck and framing species, with the weight of a standard 2×8×12 so the numbers are comparable at a glance.
- [Composite vs Wood Decking — Cost, Temperature, Lifespan](https://deckformula.com/composite-vs-wood-decking/): A comparison built on numbers rather than preference: installed cost per square foot, surface temperature, span limits
- [PVC vs Composite Decking — Where PVC Wins](https://deckformula.com/pvc-vs-composite-decking/): PVC decking is not composite with a better cap. Differences in expansion, stiffness, heat and cost, with the installation limits that catch people out.
- [Cedar vs Pressure-Treated Lumber — Rot, Cost, Fasteners](https://deckformula.com/cedar-vs-pressure-treated/): Western red cedar and treated pine compared on durability, weight, fastener compatibility and how each takes a finish
- [Hardwood Decking — Ipe, Cumaru, Garapa](https://deckformula.com/hardwood-decking-guide/): Density, movement, fastener rules and the installation cost of tropical hardwood decking. Why the material price is not the number that surprises people
- [Nominal vs Actual Lumber Size: The Conversion Table](https://deckformula.com/nominal-vs-actual-lumber/): A 2x4 is 1-1/2 by 3-1/2 inches. The full table for dimensional lumber, why the sizes exist, and the three places the difference costs money.
- [Lumber Grades Explained: What the Stamp Tells You](https://deckformula.com/lumber-grades-explained/): Select Structural, No.1, No.2, Stud and Utility: what each grade permits, which one a deck actually needs
- [Deck Board Thickness — 5/4 vs 2x6 vs 1 Inch Composite](https://deckformula.com/deck-board-thickness-guide/): What thickness actually controls on a deck board: stiffness between joists, fastener hold
- [Deck Fastener Guide — Coatings, Sizes and Quantities](https://deckformula.com/deck-fastener-guide/): Which fastener for treated wood, cedar, ipe and composite: corrosion classes, screw length rules, hanger nails versus deck screws
- [Aluminum vs Wood Deck Railing — Cost, Posts, Maintenance](https://deckformula.com/aluminum-vs-wood-railing/): Aluminum railing costs more per foot and needs fewer posts. A comparison of installed cost, post spacing, code compliance
- [Cable Railing — Cost, Post Spacing and Deflection](https://deckformula.com/cable-railing-guide/): Stainless cable railing looks minimal and costs the most. The post spacing, tensioning and deflection rules that decide whether it will pass inspection.
- [Deck Board Cupping: Why It Happens and What Fixes It](https://deckformula.com/deck-board-cupping/): Cupped deck boards explained by the moisture gradient that causes them, which fixes work, which only postpone it, and when replacement is the answer.
- [Deck Squeaks — Finding the Cause Before Adding Screws](https://deckformula.com/deck-squeaks/): What causes a squeaking deck, how to locate it precisely, and the four fixes ranked by how much decking they require you to remove.
- [Deck Rot Repair — How to Tell Cosmetic From Structural](https://deckformula.com/deck-rot-repair/): Finding rot on a deck, judging whether it is cosmetic or structural, and the repair options from board replacement to sistering a joist.
- [How Often Should You Seal a Deck? The Water Test Decides](https://deckformula.com/how-often-to-seal-a-deck/): Sealing intervals by material and climate, the water bead test that tells you it is time, and why sealing too often is as bad as not sealing at all.
- [Best Stain for a Deck — Oil vs Water-Based](https://deckformula.com/best-stain-for-deck/): Choosing a deck stain by species, exposure and existing finish. Why oil and water-based products are not interchangeable
- [How to Clean Composite Decking Without Scratching It](https://deckformula.com/cleaning-composite-decking/): Cleaning composite decking: what the cap will tolerate, how to remove the three common stains, and the tools that scratch a capped board permanently.
- [Deck Winterizing: What Actually Protects It](https://deckformula.com/deck-winterizing/): A winter checklist for a wood or composite deck: freeze-thaw damage, snow removal, ice, drainage and the tasks that should wait until spring.
- [Deck Cost Per Square Foot — What the Number Includes](https://deckformula.com/deck-cost-per-square-foot/): Installed deck cost per square foot by material and height, what is and is not in the number, and why quotes for the same deck vary by 100%.
- [Composite Deck Cost — Material, Hidden Extras](https://deckformula.com/composite-deck-cost/): What composite decking costs installed, the four extras that push the total up
- [Deck Repair Cost — By Repair Type, and When](https://deckformula.com/deck-repair-cost/): What common deck repairs cost: boards, railing posts, joists, footings, stairs and staining. Plus the threshold where repair stops making sense.

## Framing and structure

- [Deck Framing — Ledger, Joists, Beams and Footings](https://deckformula.com/framing/): The load path through a deck frame: what each member does, which decisions are arithmetic and which need a span table
- [Post Hole Calculator — Concrete, Gravel and Bag Counts](https://deckformula.com/post-hole-calculator/): Concrete and gravel per post hole, with the post volume subtracted. Enter hole diameter, depth, gravel base and post size for bags at 60 lb or 80 lb.
- [Deck Ledger Attachment — Fasteners, Flashing and Limits](https://deckformula.com/ledger-attachment-guide/): How a deck ledger attaches to a house, why the connection fails, which fastener schedules apply
- [How to Read a Deck Beam and Joist Span Table](https://deckformula.com/beam-span-tables-explained/): What each column of a span table means, why five variables interact, and why this site will not publish a span number.
- [Deck Blocks vs Poured Footings — When Each Is Acceptable](https://deckformula.com/deck-block-footing-guide/): Precast deck blocks are cheap and fast and fail predictably. Where they are permitted, where frost rules them out, and how to build on them.
- [Cantilever Rules: The Quarter-Back-Span Limit](https://deckformula.com/cantilever-rules/): How far a deck joist can overhang its beam, why the limit is a fraction of the back span, and how cantilevering changes post layout and guard loads.
- [Deck Flashing Details — Ledger, Joist Tape](https://deckformula.com/flashing-details/): Where water goes at a deck-to-house junction, the flashing sequence that works, why caulk is not flashing
- [Deck Frame Anatomy — What Each Member Does](https://deckformula.com/deck-frame-anatomy/): Ledger, joists, beam, posts, footings and blocking explained by the load each one carries
- [Joist Spacing Chart — 12, 16 and 24 Inches Compared](https://deckformula.com/joist-spacing-chart/): What joist spacing changes: decking stiffness, joist span, material cost and the feel underfoot.
- [Deck Guard Requirements: The 4-Inch Sphere Rule](https://deckformula.com/deck-guard-requirements/): When a deck needs a guard, how high it must be, what load it has to take, and the infill rule that fails more inspections than any other.
- [Deck Stair Code — Riser, Tread, Nosing](https://deckformula.com/deck-stair-code/): The IRC dimensions for exterior deck stairs: maximum riser, minimum tread, nosing projection
- [Deck Load Requirements — 40 psf Live Load](https://deckformula.com/deck-load-requirements/): The design loads a deck is built for, why 40 psf is not the same as a hot tub, and the lateral load requirement that most deck collapses trace back to.
- [Do You Need a Permit for a Deck? Height](https://deckformula.com/deck-permit-guide/): The three factors that decide whether a deck needs a permit, what the application usually requires
- [Frost Depth and Deck Footings — Why the Hole Goes Deeper](https://deckformula.com/frost-depth-footing/): How frost heave lifts a footing, how deep footings go in cold climates, and the two details that prevent heave without digging deeper.
- [Deck Code Checklist — IRC Dimensions That Get Inspected](https://deckformula.com/deck-code-checklist/): The deck dimensions inspectors actually measure — guard height, the 4-inch sphere rule, riser and tread limits, footing depth
- [How to Build a Deck: Build Order and What Breaks](https://deckformula.com/how-to-build-a-deck/): The build order for a ground-level attached deck, with the three steps that cannot be corrected later
- [How to Install Deck Boards — Gap, Fastening](https://deckformula.com/how-to-install-deck-boards/): Board orientation, gap size by material, fastener placement and the two patterns worth using.
- [How to Set Deck Posts — Depth, Anchor, Plumb and Bracing](https://deckformula.com/how-to-set-deck-posts/): Setting a post in concrete without rot or heave: hole depth, gravel base, anchor type
- [Deck Stair Layout: Marking and Cutting Stringers](https://deckformula.com/deck-stair-layout/): Laying out a stringer with a framing square: riser and tread marks, the first mark that accounts for tread thickness, and notch depth limits.
- [Deck Railing Installation — Post Anchorage](https://deckformula.com/deck-railing-installation/): Installing deck railing so it passes the 200 lb load test: post blocking, through-bolts, rail layout and the baluster sequence that keeps spacing even.
- [How to Flash a Deck Ledger — Layer Order](https://deckformula.com/how-to-flash-a-ledger/): The flashing sequence for a deck ledger, in order from the wall out
- [Deck Board Patterns — Diagonal, Picture Frame](https://deckformula.com/deck-board-patterns/): Four deck board layouts with the material, framing and joist-spacing consequences of each. Includes why diagonal laying needs 15% more board.
- [Patio Slope and Drainage — 1% Is Not Enough in Clay](https://deckformula.com/patio-slope-drainage/): How much fall a patio needs, where the water actually goes, and why a 1% slope that satisfies the code still leaves a puddle against the house.
- [Wobbly Deck Railing — Why It Moves and How](https://deckformula.com/wobbly-deck-railing/): A loose deck railing is almost always a post anchorage problem. Diagnosing whether it is the post, the blocking or the frame, with the fix for each.
- [Deck Footing Failure — Heaving, Settling](https://deckformula.com/deck-footing-failure/): Why deck footings heave in winter or sink over time, how to tell which is happening, and the repairs that work versus the ones that only hide it.

## Outdoor living and landscape

- [Pergolas, Pavers, Fences and Deck Lighting — Calculators](https://deckformula.com/outdoor-living/): Pergola rafters, patio pavers, fence posts, privacy screens and low-voltage lighting: calculators and references for the parts beyond the deck surface.
- [Pergola Rafter Calculator — Count, Length and Shade](https://deckformula.com/pergola-rafter-calculator/): Rafter count, length with overhang, total linear feet and the shade percentage your spacing actually produces.
- [Patio Paver Calculator — Pavers, Base and Sand](https://deckformula.com/patio-paver-calculator/): Paver count, loose base volume, sand and edge restraint for a patio. Base is ordered loose to compact, so the volume is larger than the finished depth.
- [Fence Calculator — Posts, Rails, Pickets and Concrete](https://deckformula.com/fence-post-calculator/): Posts, rail linear feet, picket count and concrete per hole for a fence run. Enter length, spacing, height and picket width; get quantities, not guesses
- [Fence Picket Calculator — Pickets, Posts and Rails](https://deckformula.com/fence-picket-calculator/): Picket, post and rail counts for a fence run, with the gap width that decides the picket count and the post spacing that decides everything else.
- [Privacy Screen Calculator — Slats, Spacing and Coverage](https://deckformula.com/privacy-screen-calculator/): Boards for a slatted privacy screen: count, linear feet, actual gap and the percentage of the screen that is closed, for horizontal or vertical slats.
- [Deck Lighting Calculator — Fixtures, Load](https://deckformula.com/deck-lighting-calculator/): Total load, current and voltage drop for 12 or 24 V deck lighting, with the maximum run per wire gauge and a gauge that reaches the last fixture.
- [Mulch Calculator — Cubic Yards, Bags](https://deckformula.com/mulch-calculator/): How much mulch a bed needs in cubic yards and bags, with depth guidance by bed type and the settlement allowance most estimates leave out.
- [Topsoil Calculator — Cubic Yards, Tons](https://deckformula.com/topsoil-calculator/): Topsoil volume from area and depth, converted to cubic yards, tons and bags, with the compaction factor that makes delivered soil arrive short.
- [Sod Calculator — Rolls, Pallets and the Waste You Need](https://deckformula.com/sod-calculator/): Sod quantity from area, with roll and pallet counts, an allowance for cutting around edges
- [Retaining Wall Calculator — Block Count](https://deckformula.com/retaining-wall-calculator/): Segment blocks, caps and base gravel for a block retaining wall, with the height limit above which a wall needs an engineer rather than a calculator.
- [Fire Pit Calculator — Block Count, Ring Diameter](https://deckformula.com/fire-pit-calculator/): Blocks or bricks for a round fire pit, the inner diameter you actually get
- [Patio Base Calculator — Gravel, Sand](https://deckformula.com/patio-base-calculator/): Crushed aggregate and bedding sand for a paver patio, with loose-versus-compacted depths and the excavation volume that has to be removed first.
- [Pergola Shade Calculator: Coverage From Rafter Width](https://deckformula.com/pergola-shade-calculator/): How much shade a pergola actually provides, from rafter width, spacing and sun angle. Includes why the noon number is not the number that matters.
- [Gravel Calculator — Cubic Yards, Tons and Loose Depth](https://deckformula.com/gravel-calculator/): Cubic yards and tons of gravel for a driveway, path or drainage bed, with density by aggregate type and the waste allowance to order with.
- [Deck Stair Handrail Guide — Height, Profile](https://deckformula.com/stairs-handrail-guide/): Handrail height, graspable profile dimensions, wall clearance and the 4-inch sphere rule applied to a sloped guard
- [Deck Inspection Checklist: What an Inspector Checks](https://deckformula.com/deck-inspection-checklist/): A pre-inspection walk-through in the order an inspector does it: ledger and flashing, framing connections, footings, guard and stair dimensions, decay.
- [Fence Cost — Per Linear Foot by Material](https://deckformula.com/fence-cost-guide/): Installed fence cost per linear foot for wood, vinyl, aluminum and chain link

## All tools index

- [All Deck Calculators — Boards, Joists, Stairs, Railing](https://deckformula.com/calculators/): Every calculator on DeckFormula, with what each one answers and what it deliberately leaves out. All of them show their formulas.

## How this site works

- [Methodology — How These Calculators Are Built](https://deckformula.com/methodology/): How DeckFormula produces its numbers: the formula layer, the worked examples, what we verify, what we refuse to model, and how corrections are handled.
- [About DeckFormula — What This Site Is and Is Not](https://deckformula.com/about/): What DeckFormula is, what it is not, and the standard every calculator on the site is held to. No sponsored content and no lead generation.
- [Editorial Standards — How Every Page Is Checked](https://deckformula.com/editorial-standards/): The rules every page on this site is held to: how formulas are sourced, how examples are verified, what gets refused, and how corrections are handled.
- [Corrections Log — Dated, Public, Nothing Removed](https://deckformula.com/corrections/): A public log of every substantive correction made to this site, including what was wrong and what it was changed to. Entries are dated and never removed
- [Affiliate Disclosure — How DeckFormula Is Funded](https://deckformula.com/affiliate-disclosure/): How DeckFormula is funded, which outbound links may be affiliate links, and what advertisers do and do not control on this site.
- [Contact DeckFormula — Report a Wrong Answer](https://deckformula.com/contact/): How to report a wrong answer, request a correction, or ask about the methodology behind a calculator. One address, and what happens after you write.
- [Privacy — No Cookies, No Analytics, No Tracking](https://deckformula.com/privacy/): What this site does and does not collect. No cookies, no analytics scripts, no third-party fonts

## Other pages

- [Page Not Found — Every Calculator Is Listed Here](https://deckformula.com/404.html/): That URL does not exist. This page lists every calculator, code reference and guide on the site, and none of them has moved.
- [Deck Square Footage Calculator — Area, Perimeter](https://deckformula.com/deck-area-calculator/): Square footage, perimeter and the railing run that actually gets built for rectangular and L-shaped decks.
- [Baluster Spacing Calculator: The 4-Inch Sphere Rule](https://deckformula.com/deck-baluster-spacing-calculator/): Equal baluster spacing that passes the 4-inch sphere rule, with the real clear opening printed for every bay, plus post width and shrinkage allowance.
- [Deck Gate Calculator — Frame Size, Brace Length](https://deckformula.com/deck-gate-calculator/): Gate opening, frame dimensions, diagonal brace length and board count for a single or double deck gate, with the width limit that stops a gate sagging.
- [Ledger Fastener Calculator: Count From Your Spacing](https://deckformula.com/deck-ledger-fastener-calculator/): Count lag or structural screws for a deck ledger from the spacing you supply, with the staggered two-row layout and a box count.
- [Deck Material Guide: Pressure-Treated vs Composite](https://deckformula.com/deck-material-guide/): How the three decking families actually compare on cost, span requirements
- [Deck Post Spacing Calculator — Equal Bays](https://deckformula.com/deck-post-spacing-calculator/): Divide a railing run into equal post bays, with corner and end posts counted separately and the real spacing printed for each bay.
- [Deck Skirt Calculator — Lattice, Board](https://deckformula.com/deck-skirt-calculator/): Skirt area and material count for an elevated deck, with ventilation area calculated against the 1:150 rule and the slope allowance most estimates miss.
- [Stair Stringer Calculator — Length, Angle and Board Size](https://deckformula.com/deck-stair-stringer-calculator/): Stringer length and cut angle from total rise and run, plus the lumber depth you actually need and how many stringers a given stair width requires.
- [Frost Depth in Colorado — 42–60″ (Footing Depth 48–66″)](https://deckformula.com/frost-depth-colorado/): The frost depth in Colorado is 42–60″. Footings go 6″ below that, so the hole is 48–66″. Check your local building department before digging.
- [Frost Depth in Illinois — 36″ (Footing Depth 42″)](https://deckformula.com/frost-depth-illinois/): The frost depth in Illinois is 36″. Footings go 6″ below that, so the hole is 42″. Check your local building department before digging.
- [Frost Depth in Maine — 48–60″ (Footing Depth 54–66″)](https://deckformula.com/frost-depth-maine/): The frost depth in Maine is 48–60″. Footings go 6″ below that, so the hole is 54–66″. Check your local building department before digging.
- [Frost Depth in Michigan — 42–60″ (Footing Depth 48–66″)](https://deckformula.com/frost-depth-michigan/): The frost depth in Michigan is 42–60″. Footings go 6″ below that, so the hole is 48–66″. Check your local building department before digging.
- [Frost Depth in Minnesota — 42–60″ (Footing Depth 48–66″)](https://deckformula.com/frost-depth-minnesota/): The frost depth in Minnesota is 42–60″. Footings go 6″ below that, so the hole is 48–66″. Check your local building department before digging.
- [Frost Depth in New York — 48″ (Footing Depth 54″)](https://deckformula.com/frost-depth-new-york/): The frost depth in New York is 48″. Footings go 6″ below that, so the hole is 54″. Check your local building department before digging.
- [Frost Depth in North Dakota — 60″ (Footing Depth 66″)](https://deckformula.com/frost-depth-north-dakota/): The frost depth in North Dakota is 60″. Footings go 6″ below that, so the hole is 66″. Check your local building department before digging.
- [Frost Depth in Ohio — 32″ (Footing Depth 38″)](https://deckformula.com/frost-depth-ohio/): The frost depth in Ohio is 32″. Footings go 6″ below that, so the hole is 38″. Check your local building department before digging.
- [Frost Depth in Pennsylvania — 42″ (Footing Depth 48″)](https://deckformula.com/frost-depth-pennsylvania/): The frost depth in Pennsylvania is 42″. Footings go 6″ below that, so the hole is 48″. Check your local building department before digging.
- [Frost Depth in Wisconsin — 42–48″ (Footing Depth 48–54″)](https://deckformula.com/frost-depth-wisconsin/): The frost depth in Wisconsin is 42–48″. Footings go 6″ below that, so the hole is 48–54″. Check your local building department before digging.
- [Frost Depth by State — Footing Depth for Every US State](https://deckformula.com/frost-depth/): Frost depth for every US state, with the footing depth it implies. Pick your state for the exact number your building department enforces.

## Optional

- [Methodology](https://deckformula.com/methodology/): how every number on the site is produced and checked
- [Corrections log](https://deckformula.com/corrections/): every substantive error found and fixed, in public
- [Editorial standards](https://deckformula.com/editorial-standards/): what a page must contain before it is published
- [Sitemap](https://deckformula.com/sitemap.xml): every URL