Screed calculator
A screed levels a concrete slab before tiles, laminate or wood go down. Whether you use a traditional sand-cement screed or a self-levelling compound, the quantity depends on the area and on the average thickness — and the thickness matters more than most people expect.
Measure the thickness in several places and use the average. The calculator turns it into kilograms of dry mix and whole bags.
Your measurements
Result
- Dry mix needed
- 3,000 kg
- Bags to buy
- 120 pcs
Rule of thumb for drying: about one week per centimetre of sand-cement screed before laying wood or tiles — measure residual moisture before fitting.
How the calculation works
- The thickness is converted from mm to cm.
- Dry mix (kg) = area × thickness (cm) × consumption: about 20 kg/m² per cm for sand-cement screed and about 17 kg/m² per cm for self-levelling compound.
- Bags = kilograms ÷ bag size, rounded up.
Worked example
A 5 cm sand-cement screed over 30 m² takes 30 × 5 × 20 = 3,000 kg of dry mix — 120 bags of 25 kg.
What the calculator assumes
- The consumption figures are for ready-mixed dry products, as given on typical data sheets.
- The thickness is an average; if the base is uneven, measure at several points.
When to adjust the result
- For thick screeds, mixing cement and sand on site is much cheaper than bagged screed.
- Self-levelling compounds are poured in thin layers (often up to 2–3 cm per layer, depending on the product); for large differences in level, lay a conventional screed first.
- Drying rule of thumb: roughly one week per centimetre of sand-cement screed before laying wood or tiles — measure residual moisture before fitting moisture-sensitive floors.
Frequently asked questions
How much screed do I need per square metre?
About 20 kg per square metre for every centimetre of thickness with sand-cement screed. A 5 cm screed therefore needs around 100 kg/m², or four 25 kg bags per square metre.
What is the minimum screed thickness?
It depends on the construction: a screed bonded to the slab can be thinner than one laid on insulation (a floating screed). The product's data sheet and the floor build-up drawing give the minimum.
How long does screed take to dry?
A common rule is one week per centimetre for the first 4 cm, and longer beyond that. Temperature, ventilation and the product make a big difference, so measure moisture before fitting the floor covering.