Concrete calculator
Yards or bags for slabs, footings, walls and holes — with rebar, forms, gravel base and vapor barrier.
Job
Units
Pours
Slabs, patios, driveways
Footings
Walls
Post holes, piers, columns
Ordering
Reinforcement
Slabs
Forms & base
Materials list
| Item | Qty | Unit price | Cost |
|---|---|---|---|
| Concrete | |||
| Ready-mix concrete5.43 incl. 10% · 1 truck(s) | 5.5 cu yd | $ | — |
| Reinforcement | |||
| Rebar (#4)560 LF + 10% laps | 31 sticks (20 ft) | $ | — |
| Rebar chairsabout every 3 ft | 45 ea | $ | — |
| Tie wire≈ 98 ties (every other crossing) | 1 coils | $ | — |
| Forms & base | |||
| Form boards (2×4 / 2×6)80 ft of slab edge | 6 pcs (16 ft) | $ | — |
| Form stakes | 31 ea | $ | — |
| Duplex nails, 16d | 2 lb | $ | — |
| Gravel base (compacted)4 in. under slabs + 15% compaction | 8 tons | $ | — |
| Vapor barrier, 6 mil (10×100 ft) | 1 rolls | $ | — |
How it works
- Volume ÷ 27 = cubic yards. An 80 lb bag makes about 0.6 cu ft, so a yard is about 45 bags.
- Ready-mix is rounded up to your ordering step (usually ¼ yard). Rebar adds 10% for laps.
- Add your supplier's unit prices to any line for a cost estimate; tax and markup are optional.
How to measure
- Measure inside the forms. Use the average thickness if the grade isn't level, and add extra for soft spots.
Estimates only. Coverage, sizes and waste vary by product and job — verify with the manufacturer's specs and your local building code before ordering.
Need more base gravel? Gravel calculator →