How to use
- Choose a rectangular slab, strip footing, circular slab or round column. Add separate, non-overlapping elements and enter the quantity of identical elements.
- Choose ready-mix concrete or bagged concrete. Enter your own allowance and check the unit displayed beside every dimension.
- For ready-mix, enter the supplier price and any order increment. For bags, enter the label’s mixed-concrete yield and price per bag.
- Check net volume, allowance and purchase rounding separately before copying or saving the estimate.
Calculation method
Rectangular elements use length × width × depth. Circular elements use π × (diameter / 2)² × depth or height. Each volume is multiplied by its quantity. The sum is multiplied by (1 + allowance / 100). Ready-mix is rounded up to the selected order increment, unless it is zero. Bagged concrete is rounded up to a whole number of bags using mixed yield per bag. Cost uses the purchased volume or bag count.
Worked example
A 4 × 3 m slab at 10 cm depth needs 1.2 m³ net. A 10% allowance makes 1.32 m³. At 150 USD/m³ the material estimate is 198 USD. With a 0.5 m³ order increment, buy 1.5 m³ for 225 USD. Alternatively, 12 L mixed yield per bag requires 110 bags; at 6 USD each that costs 660 USD.
Assumptions and limits
This is a material quantity estimate. It does not design foundations, select strength, reinforcement or a concrete mix recipe. Strip footings must use non-overlapping runs: corners and intersections are counted once. Supplier minimums, truck capacity, pumping, delivery, tax, labor and excavation are excluded.
Units, prices and saved estimates
Physical values are stored internally in metres, square metres, cubic metres or kilograms as appropriate. Changing measurement units converts their display; choosing a currency changes its label without applying an exchange rate. Purchase quantities use unrounded calculations. Money is shown to two decimal places.
Edits can be saved in this tab. Optional device saving lasts seven days after the last save. Copy, TXT download and a separate printable report use the current valid estimate. Delete draft removes saved inputs without resetting the visible form. The privacy choices page can remove all calculator drafts.
For practical measurement decisions, read measuring concrete and planning an order.