Construction calculator
Concrete Calculator — Volume, Bags & Cost
Calculate slabs, footings, walls and post holes in US customary or metric units. Compare ready-mix and whole-bag quantities, add a waste allowance, and estimate material cost using your own supplier price.
Project measurements
Your measurements. Your supplier prices. Your actual figures.
How to use it
Measure the pour, then choose how you plan to buy.
Add each slab, footing, wall or round pour as its own section. ProjectFigures converts every valid dimension to metres internally, sums the exact raw volume, then applies your waste allowance once to the project total. The planning volume can then be compared as ready-mix or whole bags.
Use finished concrete dimensions rather than form-board thickness. For slabs, enter length × width × thickness. For footings, use total run × width × depth. For walls, use length × height × thickness. For post holes, use hole diameter × depth and optionally subtract an embedded round or square post.
Methodology
Transparent concrete math.
- Rectangular volume: length × width × depth × quantity
- Round volume: π × radius² × depth × quantity
- Planning volume: raw project volume × (1 + waste %)
- Bag purchase: planning volume ÷ selected mixed yield, rounded up to a whole bag
- Supplier increment: planning volume rounded up only when you enter a supplier sale increment
Calculations use full-precision SI normalization internally: 1 ft = 0.3048 m exactly, 1 in = 0.0254 m exactly, 1 ft³ = 0.028316846592 m³, and 1 yd³ = 0.764554857984 m³. Display rounding happens only after the calculation.
Checked examples
Two useful reference cases.
US slab: 10 ft × 10 ft × 4 in with 10% waste is approximately 1.36 yd³. Using the QUIKRETE 80 lb reference yield of 0.60 ft³ per bag, the purchase quantity is 62 whole bags.
Metric slab: 4 m × 3 m × 100 mm with 10% waste is 1.32 m³. At a reference yield of 0.01 m³ per bag, the purchase quantity is 132 whole bags.
Bagged concrete
Bag weight does not tell you mixed yield.
Two products with the same package weight can publish different mixed yields. ProjectFigures therefore uses named manufacturer reference profiles and keeps the yield editable. Your product data wins. Never scale a bag yield from weight alone.
FAQ
Concrete calculator questions
How much extra concrete should I add?
ProjectFigures starts with a visible 10% planning assumption, but it is editable from 0% to 100%. The calculator does not claim one waste percentage is correct for every job.
Should I order in cubic yards or cubic metres?
Use the unit your supplier sells in. US projects commonly use cubic yards, while the UK and Australia commonly use cubic metres. Canada often combines feet/inches field measurements with cubic-metre ordering.
Does the cost estimate include labor or tax?
No. V1 estimates concrete material cost only from prices you enter. Labor, forming, reinforcement, pumping, tax, overhead and profit are excluded.
Can I combine several pours?
Yes. Add up to 25 sections. Waste is applied once after the exact raw section volumes are summed.
Connected workflow
Turn material quantities into a complete job price.
Once your concrete quantity and material cost are clear, continue through the connected ProjectFigures workflow.
Contractor Job Pricing Calculator adds labor, other direct costs, contingency, overhead and planned profit.
Labor Burden Calculator helps establish true employer labor cost before the complete job is priced.
Concrete quantity and entered-price material estimates only — not structural advice.