Floor Screed Calculator
Calculate floor screed: mix volume in m³, sand-concrete M300 weight in kg and 40-kg bags by room area and layer thickness.
Floor area in square meters
Screed layer thickness in centimeters
1800 kg/m³ for sand-concrete M300
Calculation formula
Volume = Area × Thickness ÷ 100; Weight = Volume × Density; Bags = Weight ÷ 40
Thickness in cm is divided by 100 to convert to meters. Sand-concrete M300 density is about 1800 kg/m³. Bag count is rounded up.
About the floor screed calculator
This calculator estimates how much dry mix you need for a floor screed: volume in cubic meters, total weight in kilograms, and the number of standard 40-kg sand-concrete bags.
By default we use the density of sand-concrete M300 — about 1800 kg/m³. If you use a custom cement-sand mortar or another self-leveling compound, replace the density with the value from the bag or technical data sheet.
All calculations run locally in your browser — nothing is uploaded. Add a 5–10% safety margin on top of the result to cover uneven substrates and waste.
Calculator benefits
Instant calculation
Change the area or thickness and the consumption updates automatically
Bag count included
We show the number of 40-kg sand-concrete bags ready for purchase
Any mix grade
Override the density to match a custom cement-sand mortar or self-leveling compound
FAQ
Which sand-concrete M300 should I choose for a screed?
For a residential screed, any reputable bagged sand-concrete M300 works. Check the production date — fresh cement sets better — and choose a mix with sand fraction 0–5 mm for a 3–8 cm layer.
Does a screed need reinforcement?
A 100×100 mm welded mesh of 3–4 mm wire is recommended from 4 cm thickness and required over insulation or underfloor heating. For thin layers on a flat substrate you can mix in polypropylene fiber instead.
How long does a floor screed take to dry?
You can walk on it after 1–3 days, but laminate or tile installation should wait around 28 days (about one week per centimeter of thickness). Cover the screed with film and mist it with water for the first 3–5 days to prevent cracks.
What is the minimum screed thickness?
Sand-concrete M300 needs at least 3 cm on a flat substrate, otherwise it will crack. Over underfloor heating use no less than 4–5 cm above the pipes or mats. For very thin layers (0.5–2 cm) use a self-leveling compound.