From this site

One project, every trade

Each calculator adds its lines to a single estimate — consolidated BOM, schedule and cash-flow included.

Open My Project →

Deck Footing Calculator

Estimate the minimum number of footings needed around a deck's perimeter based on standard spacing.

Computed in your browser — nothing you enter is uploaded. Figures are presented for United States against IRC 2024, and every formula is cited under regulatory standards below.

Last verified 2026-08-25 · v1.0.0

Market
Imperial · sales tax
13.12 ft11.48 ft
Schematic, drawn to the proportions you entered — not to scale on screen.

Minimum footings needed

7 footings (minimum)

Check your inputs

Footing count and placement are structural and code-critical — this is a rough planning estimate only. Always verify final footing count, size, and depth (including frost depth) against your local building code or a structural engineer before digging.

Perimeter beam length
49.21 linear ft

At the values currently entered, the minimum footings needed works out to 7 footings (minimum). Confidence is moderate: the method is sound, but real materials and site conditions vary. Figures are shown for United States, where IRC 2024 is the governing residential reference; switch the market above if you are building elsewhere.

Add the equipment this sizes

This result is a specification — 7 footings (minimum) — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.

Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — confirmed fixes become pinned regression tests.

[Schema Verified] Computed in alignment with American Concrete Institute (ACI 318-19) formulas and International Residential Code (IRC 2024) spatial boundaries.

Regulatory standards & verification citations

  • Footing count = perimeter beam length / footing spacing, rounded up; 6-8 ft spacing is a commonly used residential deck framing guideline, though actual spacing depends on joist/beam size and species per local span tables

Your workspace

Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

Frequently asked questions

Why does this only count perimeter footings?
This estimates footings along the outer beam line, which covers most simple rectangular deck designs. Larger decks, multi-level decks, or decks with a beam down the middle need additional interior footings not captured here.
Is footing spacing the same as joist spacing?
No — joists are typically spaced 12-16 in apart and support the decking boards; footings support the beams underneath the joists and are spaced much farther apart, as this calculator estimates.
Does frost depth affect footing count?
No — frost depth affects how deep each footing must be dug (to below the frost line so the ground doesn't heave it), not how many footings you need. Check your local code for the required depth in your area.