Deck footing grid estimator

Deck Footing Calculator

Estimate a simple deck footing grid from deck length, deck width, maximum footing spacing, hole diameter, depth, waste, and concrete bag yield. It supports deck footing and gazebo footing searches without pretending to approve structure.

Units

Deck length (ft)Deck width (ft)Max length spacing (ft)Max row spacing (ft)Footing hole diameter (in)Footing hole depth (in)Concrete waste (%)Concrete yield per bag (ft³)Form tube cost ($)Cost per concrete bag ($)

Footings to form

Footing grid

Concrete bags

Rough cost

Deck footings need structural and frost checks

This is a footing count and concrete quantity estimator only. Footing size, depth, frost line, soil bearing, uplift, beam spans, post bases, permits, and local deck code must be verified before digging or pouring.

Android App

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Deck Post Calculator

Estimate posts and beam-line spacing after footing locations are planned.

Post Hole Concrete Calculator

Use a round-hole concrete calculator for non-deck posts and mailbox holes.

Deck Cost Calculator

Roll deck framing, boards, railing, labor, and footing allowances into a rough total.

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Deck footing formula

Footings along length = ceiling(deck length ÷ max length spacing) + 1

Footing rows = ceiling(deck width ÷ max row spacing) + 1

Total footings = length footings × footing rows

Concrete bags = footings × round hole volume × (1 + waste %) ÷ bag yield

Sample takeoff

A 20 ft by 12 ft deck with 6 ft maximum spacing forms a 5 by 3 grid, or 15 footings. With 12 in by 36 in holes, 10% waste, and 0.6 ft³ bag yield, order about 65 bags.A 6 m by 3.6 m deck with 1.8 m maximum spacing forms a 5 by 3 grid, or 15 footings. With 300 mm by 900 mm holes, 10% waste, and 0.017 m³ bag yield, order about 62 bags.

Deck Footing Calculator FAQ

How many deck footings do I need?+

For a quick grid estimate, divide deck length and width by the maximum footing spacing, round each direction up, add one line at each edge, then multiply the two counts.For a quick grid estimate, divide deck length and width by the maximum footing spacing, round each direction up, add one line at each edge, then multiply the two counts.

Does this choose footing diameter or depth?+

No. Enter the diameter and depth required by your plans, frost line, soil, local code, or engineer. This calculator only turns those dimensions into quantities.No. Enter the diameter and depth required by your plans, frost line, soil, local code, or engineer. This calculator only turns those dimensions into quantities.

Can this estimate gazebo footings?+

Yes for a simple rectangular footing grid. Round, polygon, and point-load layouts need a specific plan.Yes for a simple rectangular footing grid. Round, polygon, and point-load layouts need a specific plan.