Free tool
Deck Material Calculator
Enter deck dimensions, joist spacing, and waste allowance to get a full structural takeoff: joist count, decking linear feet, screws, hangers, and footing concrete. The same geometry runs inside Drevanto's certified Instant deck assembly.
Result
Results updated.
| Decking boards | 357linear ft |
|---|---|
| Joists at 16 in. on center | 10pieces |
| Deck screws (2 per board crossing) | 540screws |
| Railing incl. waste | 40linear ft |
| Concrete mix (60 lb bags) | 12bags |
Formula
- decking LF = ceil(width × 12 ÷ 5.5 in. exposure) × length × (1 + waste)
- joists = ceil(length × 12 ÷ 16) + 1
- screws = board rows × joists × 2
- railing LF = railing input × (1 + waste)
- concrete bags = footings × 2 (assumes 12 in. dia × 12 in. deep footing)
Assumptions
- 5.5 in. board exposure (nominal 6 in. decking laid tight).
- Joists at 16 in. on center, running the length of the deck.
- Two 60 lb concrete bags per footing (about 0.8 cu ft each).
- Rectangular, single-level deck with a simple railing layout.
What this does not cover
- No beam, ledger, stair, or post sizing — those are structural and must be verified against local code.
- No hardware (hangers, post bases, flashing) — connector counts depend on your framing plan.
- Material planning aid only; not a quote and not a structural design.
Planning aid only — not a quote. Quantities use documented rules of thumb; verify against your plans, local codes, site conditions, and real supplier pricing before ordering or bidding.
Methodology
The calculator walks the deck in the order it gets built. Footings first: a 12-inch diameter hole 12 inches deep is about 0.785 cubic feet, so a 60 lb bag (0.45 cubic feet of concrete) covers roughly half a hole — two bags per footing at 6×6 spacing. Joists follow from spacing: width in inches divided by on-center spacing, rounded up, plus one rim-side joist. Decking rows come from the 5.5-inch exposure of a nominal 5/4×6 board; rows times length gives linear feet, inflated by your waste percentage. Fasteners assume two screws per joist crossing, plus one joist hanger per joist.
Worked example: a 12 × 12 ft deck, 16 in. o.c., 10% waste
- Joists = ceil(144 ÷ 16) + 1 = 10
- Decking rows = ceil(144 ÷ 5.5) = 27 rows → 27 × 12 = 324 LF, ×1.1 waste = 357 LF
- Screws = 27 rows × 10 joists × 2 = 540
- Footings at 6×6 spacing = ceil(144÷72)×ceil(144÷72) = 4 holes → 8 × 60 lb bags
Frequently asked questions
Does this include railing and stairs?
No. Railings and stairs are their own measured lines with code-specific requirements, so they are deliberately excluded. Take them off separately.
Why is footing count an estimate?
Real footing count and depth come from load, soil, and frost depth — set by your local code. The 6×6 ft grid here is a planning placeholder; verify with your building department.
Is this connected to Drevanto Instant Estimates?
It uses the same documented geometry, but this page runs open formulas in your browser. The certified deck assembly in Drevanto Beta 2 produces a full editable estimate from a scope description — see the certified example on the Instant Estimates page.
Certified benchmark · 2026-08-21
In 520 certified profile-mode generations across 26 supported Instant assemblies on Windows (profile/AOT) and an Android API 36 emulator, supported jobs became editable estimates in a median of 0.028 seconds (rounded); the measured 95th percentile was 48.008 milliseconds (approximately 0.048 seconds), with 0 generative-AI provider calls.
- median, supported jobs
- 0.028 sec
- certified generations
- 520
- supported assemblies
- 26
- failures · 0 AI provider calls
- 0
Certified supported jobs only. Editable output; contractor pricing and field verification remain in control. Full methodology and results
See it run on your own jobs
The private Drevanto beta is the real, editable product — not a website demo. Apply, and we will follow up by email.