Inputs to result
Cubic feet = length (ft) × width (in) ÷ 12 × depth (in) ÷ 12; cubic yards = cubic feet ÷ 27; order yards = geometric yards × (1 + allowance% ÷ 100).
Concrete & Masonry
Concrete Footing Calculator
Calculate concrete volume in cubic feet and cubic yards for continuous rectangular footings using total length, width, depth, and waste.
Enter the footing's total centerline length, width and depth. The result gives exact geometric cubic yards and a separate order estimate with your chosen allowance.
Calculation and worked example reviewed 2026-11-12. See our calculation methodology.
FREE access0 signup
Concrete & Masonry
US UNITSEnter your measurements
YOUR ESTIMATE
7.78 cu yd to plan7.41 cu yd geometry200 cu ft before allowance.
5% order allowance shown separately.
Formula and example
How this calculation works
This estimator converts your entered jobsite inputs (total footing length, footing width, footing depth, order allowance) into consistent US trade units, computes the exact geometric baseline first, and then applies any selected waste or order allowance so you can verify both numbers before purchasing materials.
How does the concrete footing calculator formula work?
Cubic feet = length (ft) × width (in) ÷ 12 × depth (in) ÷ 12; cubic yards = cubic feet ÷ 27; order yards = geometric yards × (1 + allowance% ÷ 100).
(Concrete Footing Calculator)where:
- Total footing length – Entered in ft (default reference: 100 ft);
- Footing width – Entered in in (default reference: 24 in);
- Footing depth – Entered in in (default reference: 12 in);
- Order allowance – Entered in % (default reference: 5 %);
Check the math
A 100 ft footing, 24 in wide and 12 in deep needs 200 cu ft or 7.41 cu yd geometrically. A 5% allowance brings the planning order to 7.78 cu yd.
Quick lookup chart
Continuous Concrete Footing Volume per 100 Linear Feet
Geometric volume for 100 linear feet of continuous rectangular trench or formed footing.
| Footing Size (W × D) | Cross-Section | Geometric Volume (100 ft) | Order w/ 5% Allowance |
|---|---|---|---|
| 16 in × 8 in | 0.89 sq ft | 3.29 cu yd | 3.46 cu yd |
| 20 in × 10 in | 1.39 sq ft | 5.14 cu yd | 5.40 cu yd |
| 24 in × 12 in | 2.00 sq ft | 7.41 cu yd | 7.78 cu yd |
| 30 in × 12 in | 2.50 sq ft | 9.26 cu yd | 9.72 cu yd |
Before you use this result
Rectangular continuous footings only. Soil irregularity, stepped footings, intersections, reinforcement displacement, delivery minimums and required footing design are outside this calculation.
- Measure continuous footing length along the centerline so corner intersections are neither double-counted nor shorted.
- Earth-trenched footings typically require 8% to 10% overage due to trench wall sloughing and uneven bottom excavation, compared to 5% for wood forms.
- Verify footing width, depth, soil bearing pressure, frost line depth, and continuous rebar schedule with local building code.
Questions answered
Calculator FAQ
Do I enter inches or feet for footing width?+
Enter width and depth in inches. The calculator converts each to feet before computing cubic feet.
Is the displayed order quantity a supplier order?+
It is a planning estimate. Confirm forms, excavation, overage and delivery increments with the supplier before placing an order.