— How the yard calculator works
From mixed shapes to one truck delivery.
Most real concrete jobs aren't a single rectangle. A typical house pour might include the slab, four corner footings, a couple of porch tubes, and a set of front steps — all from one truck. Adding shapes individually and ordering each separately wastes money on short-load fees and creates cold joints when the second pour arrives an hour late.
This calculator lets you stack shapes into one total. Each item is computed with the right formula, then summed, with waste applied at the end. The pipeline:
- Pick a shape — slab, footing, column, tube, stairs, or curb & gutter.
- Enter its dimensions and the quantity (one slab, four footings, eight tubes).
- Hit "Add to total." The item lands in the running list with its computed volume.
- Move to the next shape and repeat.
- The right panel sums every item, adds your waste factor, and gives the figure to call the ready-mix plant with.
The hero readout is in your country's primary unit — cubic yards in the US and Canada, cubic metres in the UK and Australia. Bag counts assume Quikrete-class pre-mix yields (~0.60 ft³ per 80 lb bag, ~0.45 ft³ per 60 lb bag). The weight figure assumes ~4,000 lb per cubic yard (~2,400 kg/m³) — useful for planning truck access, formwork loading, and trailer transport on DIY jobs.
— Shape formulas
How each shape is calculated.
Once each shape is computed, the calculator converts internally to cubic metres for summing, then displays the total in your country's preferred unit. 27 cubic feet = 1 cubic yard. 1 cubic yard = 0.7646 cubic metres. Most ready-mix plants will round your order up to the next quarter unit (0.25 yd³ in the US, 0.25 m³ in the UK and Canada, 0.20 m³ in Australia).
— Common estimating mistakes
Why your order comes up short.
- Mixing units. Putting feet in one input and inches in another is the most common error. Always convert thickness to feet (4 inches = 0.333 ft) before multiplying, or use a calculator that handles the conversion automatically.
- Forgetting subgrade irregularity. If your excavated trench is half an inch deeper than nominal across 100 sq ft, that's an extra 0.15 yd³ you'll need. Bumping waste from 5% to 8% covers this in most cases.
- Using triangle math for stairs. Stairs aren't a triangle — they're a stack of rectangular blocks. Step 2 sits on a footprint of (run × 2), step 3 on (run × 3), and so on. Triangle approximations under-count by 15–25%.
- Ignoring wall taper. Basement and retaining walls often taper from a wider base to a narrower top. Average the top and bottom thicknesses before multiplying — never just use the wall's stated thickness at one end.
- Confusing yards and feet. Ready-mix is sold by the cubic yard. Bag concrete coverage is rated in cubic feet. Mixing them up is how a job ordered as "3 yards" arrives as a quarter of what was needed.
The short-pour penalty.
Ready-mix plants charge a small-load fee for partial loads — typically $50–$150 in the US, £60–£100 in the UK, A$130–A$180 in Australia, C$100–C$150 in Canada. Going back for a second delivery to make up for under-ordering costs more than just over-ordering by 5%. Order long, pour the extra into a footing or post hole if you have one ready.
JM
Reviewed by Jordan Mireles, P.E.
Licensed civil engineer · 14 years residential and light commercial concrete. Volume formulas verified against ACI 301 specifications, ASTM C94 ready-mix delivery standards, and standard estimating texts. Last reviewed May 2026.