Know how much concrete before you pour.
Free calculators for volume, cost and site-mixed materials, with plain-English guides for homeowners and tradespeople.
Pick a tool
Volume calculator
Slabs, footings, walls, columns, steps and kerbs, with waste and rounding.
Cost estimator
Concrete, delivery, pump, labour and VAT in one total.
Site-mix materials
Cement bags, sand and aggregate for the mix ratio you choose.
Unit converter
m³, yd³, litres, tonnes, psi, MPa and more.
How it works
Measure
Take length, width and depth on site. Pick the shape that matches your job.
Calculate
Get the volume with waste added, rounded to a size a supplier can deliver.
Plan the spend
Turn that volume into a cost, or into bags and tonnes if you are mixing yourself.
Common questions
Do I need to add a waste allowance?
Yes. Uneven ground, spillage and slightly bowed formwork all use extra concrete. Most jobs allow 5–10%, and awkward shapes may need more.
Should I round my order up?
Usually. Running short mid-pour can leave a cold joint and cost another delivery fee. Rounding up to the nearest 0.1 m³ is a sensible habit.
Which units should I measure in?
Whatever you measured in. Choose the unit before you type, and the calculator converts everything to cubic metres.
How accurate are the results?
They are only as good as your measurements. Measure at several points if edges are not square and use the average.
Ready to size your pour?
Open the calculatorVolume calculator
Work out how much concrete a job needs.
What are you pouring?
Enter your measurements to begin.
- Volume before waste
- 0.00 m³
- Waste added
- 0.00 m³
- Volume with waste
- 0.00 m³
- Cubic yards
- 0.00 yd³
- Litres
- 0 L
- Approx. weight
- 0.0 tonnes
Weight assumes about 2.4 tonnes per m³. The Cost and Site mix pages reuse this volume.
Estimate the cost
Prices vary by supplier and region. Replace these figures with your own quotes.
Includes VAT.
- Concrete
- £0.00
- Short-load charge
- £0.00
- Delivery
- £0.00
- Pump hire
- £0.00
- Labour
- £0.00
- Other
- £0.00
- Subtotal
- £0.00
- VAT
- £0.00
Mix it yourself
Cement, sand and coarse aggregate for a mix ratio by volume.
Rounded up to whole bags.
- Cement
- 0 kg
- Sharp sand
- 0.00 tonnes
- Coarse aggregate
- 0.00 tonnes
- Water (approx.)
- 0 L
- Dry volume to mix
- 0.00 m³
Uses a dry-to-wet factor of 1.54, cement 1,440 kg/m³, sand 1,600 kg/m³, aggregate 1,500 kg/m³ and a 0.5 water-cement ratio. A guide only, so buy a little extra.
Convert units
Handy numbers
- Litres in 1 m³
- 1,000
- ft³ in 1 yd³
- 27
- Light-use slab depth
- 100 mm
- Waste allowance
- 5–10%
- Fresh concrete density
- ≈2,400 kg/m³
Guides
Short, practical notes to help you plan a pour. General guidance only: always follow your designer’s specification and local building rules.
Choosing a concrete strength
Strength is written as a class such as C20/25 (cylinder strength / cube strength in MPa). Higher numbers cost more, so match the grade to the job.
- C8/10: blinding layers and non-structural fill
- C15/20: simple foundations and trench fill
- C20/25: domestic floors, paths and light-duty bases
- C25/30 and above: driveways, structural work and heavier loads
For anything structural, use the grade your engineer specifies.
Ready-mix or mix on site?
Ready-mix arrives consistent and quick, and suits anything over about a cubic metre. Site mixing suits small repairs and awkward access, but quality depends on careful batching and a lot of labour. Compare the two on the Cost and Site mix pages before you decide.
Preparing for a pour
- Compact the sub-base and check levels before the formwork goes in.
- Brace formwork so it cannot bow under the weight.
- Book delivery, a pump if needed, and enough helpers for the full volume.
- Have tools ready: rakes, screed board, float, edging trowel and curing sheet.
Weather and curing
Heat dries the surface too fast and cold slows setting. In warm weather keep the surface damp and shaded. In cold weather protect against frost for the first days. Keep concrete covered and moist for several days to build strength and limit cracking.
Reducing waste
Measure the finished depth at several points, add a sensible allowance and round up. Having a little extra on hand is cheaper than a second delivery.
About PourWise
Simple tools for people who work with concrete.
Our aim
PourWise exists to take the guesswork out of ordering concrete. Enter your measurements and get clear numbers you can hand to a supplier or use to plan a budget.
Everything runs in your browser, so nothing you type is sent anywhere.
A note on accuracy
Results are estimates based on the measurements and assumptions shown next to each tool. They are not a substitute for professional design, a structural specification or a supplier quote. Check anything critical before ordering.
Contact us
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