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Estimate concrete for strip footings, wall footings and post footings from length, width and depth, with cubic yards, cubic metres, bag checks, waste allowance and a printable footing pour note.
Calculator
Width feet = footing width inches ÷ 12. Depth feet = footing depth inches ÷ 12. Base cubic feet = length feet × width feet × depth feet × number of footings. Cubic yards = cubic feet ÷ 27. Order volume = base volume × (1 + waste percent ÷ 100). Cubic metres = cubic yards × 0.764554857984. Bags = ceiling(order cubic feet ÷ bag yield cubic feet).
This is the method behind the answer, so the result can be checked rather than simply trusted.Visual grid
Length, area, volume and material estimates are grid problems too: measure the space, account for edges and allowances, then turn the pattern into a number you can use.
Space calculations turn a real surface, room, run or volume into cells, edges and allowances that can be quoted, ordered or checked.
CalculationTime
Width feet = footing width inches ÷ 12. Depth feet = footing depth inches ÷ 12. Base cubic feet = length feet × width feet × depth feet × number of footings. Cubic yards = cubic feet ÷ 27. Order volume = base volume × (1 + waste percent ÷ 100). Cubic metres = cubic yards × 0.764554857984. Bags = ceiling(order cubic feet ÷ bag yield cubic feet).
Use this space on the printed report for client, supplier, classroom, job-location, measurement, quote or approval notes.
Width feet = footing width inches ÷ 12. Depth feet = footing depth inches ÷ 12. Base cubic feet = length feet × width feet × depth feet × number of footings. Cubic yards = cubic feet ÷ 27. Order volume = base volume × (1 + waste percent ÷ 100). Cubic metres = cubic yards × 0.764554857984. Bags = ceiling(order cubic feet ÷ bag yield cubic feet).
For one 40 ft footing that is 16 in wide and 12 in deep, width = 16 ÷ 12 = 1.333 ft and depth = 1 ft. Base volume = 40 × 1.333 × 1 × 1 = 53.33 ft³, or 1.98 yd³. With a 10% allowance, order about 2.17 yd³.
Master’s Tip: print the footing dimensions before ordering concrete and keep structural design separate from quantity takeoff. A trench that is only two inches wider than planned can materially change the order on a long run.
Standard or basis: rectangular volume arithmetic with 27 cubic feet per cubic yard and 1 cubic yard ≈ 0.764554857984 cubic metres. Use local building codes, permit drawings, engineer details and ready-mix supplier requirements as the authority for structural footing work.
Methodology & Accuracy
CalculationTime pages are built around visible arithmetic: the formula, assumptions, worked example and practical limitations are shown so the result can be checked rather than simply trusted.
Width feet = footing width inches ÷ 12. Depth feet = footing depth inches ÷ 12. Base cubic feet = length feet × width feet × depth feet × number of footings. Cubic yards = cubic feet ÷ 27. Order volume = base volume × (1 + waste percent ÷ 100). Cubic metres = cubic yards × 0.764554857984. Bags = ceiling(order cubic feet ÷ bag yield cubic feet).
Standard or basis: rectangular volume arithmetic with 27 cubic feet per cubic yard and 1 cubic yard ≈ 0.764554857984 cubic metres. Use local building codes, permit drawings, engineer details and ready-mix supplier requirements as the authority for structural footing work.
Where a calculator follows a named legal, trade or industry standard, that standard is cited visibly. Otherwise the page uses transparent general arithmetic and states its limits.Master’s Tip: print the footing dimensions before ordering concrete and keep structural design separate from quantity takeoff. A trench that is only two inches wider than planned can materially change the order on a long run.
Convert footing width and depth from inches to feet, then multiply length × width × depth × number of footings. Divide cubic feet by 27 for cubic yards and add a separate waste allowance.
Usually yes. A visible allowance helps cover over-excavation, uneven trench bottoms, spillage and supplier rounding. The right margin depends on site conditions and supplier minimums.
No. It estimates concrete quantity only. Footing dimensions, reinforcement, soil capacity, frost depth and code compliance need local drawings, inspection or professional advice.
The page divides the order cubic feet by the bag yield you enter, then rounds up to whole bags. Check the yield printed on the exact bag product.
Print the length, width, depth, number of footings, base cubic feet, cubic yards or cubic metres, allowance, bag yield, formula, assumptions, page URL, date and site notes.
Footing estimates are simple volume calculations, but the consequences of confusing design and quantity are serious. A useful calculator keeps the concrete takeoff visible while warning that structural adequacy belongs to local code, drawings and professional judgement.
Length, width and depth can estimate concrete volume, but they do not prove that a footing is suitable for the load, soil, frost conditions or inspection rules.
Footing concrete is often poured into an excavated trench or form. Real trenches can be wider, deeper or rougher than the drawing, which is why the allowance should remain visible.
A one-page record with dimensions, allowance, supplier unit and notes helps compare the measured takeoff with the concrete ordered, delivered and poured.