Free tool
Floor screeding calculator
Plan your project in seconds. Enter your room size, screed depth and mix — we'll work out the volume, weight and materials you'll need for traditional sand & cement screed or liquid (flowing) screed.
Your project
All measurements in metres and millimetres. Results update instantly.
Typical: bonded 25–40mm · unbonded 50–65mm · floating / UFH 65–75mm · liquid 45–55mm.
We recommend 10% for offcuts, levelling and overpump.
Estimated quantities
Floor area
20 m²
Screed volume (with waste)
1.43 m³
Estimated weight
3.15 tonnes
Cement (25kg bags, 4:1)
25 bags
Sharp sand
2.52 tonnes
Figures are guidance only — actual quantities depend on site conditions, substrate, mix design and supplier. Want it priced and supplied? Send the numbers below for a free, fixed quote.
Get a fixed quote
Send your figures and we'll come back with a no-obligation price for supply and laying.
How to calculate floor screed quantities
Working out how much floor screed you need is a three-step calculation: area, volume, then materials. Getting the figures right keeps the project on budget and avoids wasted deliveries.
1. Calculate the floor area
Measure the floor length and width in metres and multiply them together. For irregular rooms, break the floor into rectangles and add the areas. Area (m²) = length × width.
2. Calculate the screed volume
Multiply the area by the screed depth in metres (depth in mm ÷ 1000). Volume (m³) = area × depth. Always add a waste allowance — 10% is sensible for most jobs.
3. Convert to materials
Traditional sand & cement screed weighs around 2,200 kg per cubic metre. A standard 4:1 mix means roughly 80% sharp sand and 20% cement by weight. Liquid (anhydrite) screed is sold by the cubic metre or by the litre — 1 m³ equals 1,000 litres.
Typical screed depths
- Bonded screed: 25–40 mm
- Unbonded screed: 50–65 mm
- Floating screed (insulation below): 65–75 mm
- Underfloor heating — traditional: 65–75 mm above pipes
- Underfloor heating — liquid screed: 45–55 mm above pipes
Liquid vs traditional screed
Liquid screed flows into place, self-levels and is ideal over underfloor heating thanks to better thermal conductivity. A traditional sand & cement screed is hand-finished, more forgiving on uneven substrates, and accepts foot traffic sooner.