Deck Footing Calculator

Start the support side of the job fast: estimate how many support lines, posts, and footings the deck likely needs before you move into exact hole diameters or concrete bag counts.

Operated by: Cloudtopia Maintenance: Updated when formulas, supplier packaging, or guidance change.
How to use this page

Use this page for a fast bridge number or sanity check, then continue into the related calculators or guides below when the decision needs more than a raw conversion.

Units:
This utility owns support counts and the starter footing schedule. Use it to figure out how many supports the deck likely needs, then use the post-hole concrete calculator if you want bag counts for each known hole.
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Next support steps

Post Hole Concrete Calculator

Calculate concrete bags per fence, gate, deck, and mailbox post hole

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Deck Board Calculator

Calculate deck boards, fasteners, waste, and surface-board takeoff

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Deck Railing Calculator

Calculate deck railing posts, balusters, panel kits, cable rail, and handrail counts

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Concrete Calculator

Calculate slab concrete, bag counts, and ready-mix buying plans

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Why this utility stays narrow

Support planning is not the same as concrete-bag math. A deck can fail long before the bag count is wrong if the support layout is wrong. This page answers the earlier question: how many supports and starter footings should I even be planning for?

Posts per line ≈ ceil(deck length ÷ post spacing) + 1

From there, the framing mode decides how many support lines the structure probably needs, and the result turns that into a starter footing schedule you can carry into the post-hole concrete calculator or your permit review.

FAQ

What does this deck footing calculator own? +
It owns the support count and starter footing schedule: support lines, support posts, footing count, corner vs intermediate footings, and the diameter/depth band. It does not replace bag-count math for a specific hole geometry.
Why is this different from the post-hole concrete calculator? +
The post-hole concrete calculator is excellent once you already know how many holes you are digging and how big each one is. This utility comes one step earlier: it helps answer how many deck supports you probably need in the first place.
Is this enough for permit drawings or engineering? +
No. It is a project-planning utility, not stamped structural design. Taller decks, free-standing decks, and unusual site conditions should still be checked against local code and any required engineering review.