Floor screed calculator
Estimate screed volume and the number of dry mix bags for a floor.
Fill in the fields and the result will appear here automatically.
Estimate layer volume, dry mass and whole bags from area, mean thickness and an entered consumption rate. Use the rate and bag weight for the actual mix, converting consumption to kg/(m²·cm). Reserve is a purchasing allowance and does not replace measuring the substrate profile. This model does not choose allowed thickness, mix composition, reinforcement or drying time.
How it works
Formula and logic
The area is length × width or an entered area. Volume in m³ = area in m² × thickness in cm/100 × (1 + reserve/100). Dry mix in kg = area × thickness in cm × entered kg/(m²·cm) consumption × the same reserve factor. Purchasing mass is rounded up to a whole kilogram; bags are separately rounded up from the unrounded mass/bag weight. Price is per whole bag in RUB. Convert a product rate in kg/(m²·mm) by multiplying by 10; a rate per 10 mm equals the rate per 1 cm. Water, wet-mix density, reinforcement and strength are not calculated. Uneven floors require an area-weighted mean thickness; the midpoint of minimum and maximum works only for an appropriate uniform profile. Drying time and allowed thickness depend on the system and are not determined here.
Example
A 20 m² area, 5 cm layer, entered 18 kg/(m²·cm) consumption and 10% reserve give 1.1 m³ and 1,980 kg. With 25 kg bags, round up to 80 bags.
Fields and units
- Mode — By room / By area
- Room length — m
- Room width — m
- Known area — m²
- Mean layer thickness — cm
- Dry-mix rate per 1 cm — kg/(m²·cm). Unit kg/(m²·cm): multiply a per-mm rate by 10. Blank uses 18; 0 yields 0 mix and bags.
- Bag mass — kg
- Reserve — %. Chosen non-negative percentage; no universal rate is prescribed. Blank means 0.
- Price per bag — RUB. Price in RUB; no currency exchange. Blank or 0 hides cost.
How to use
- — Choose how to define the floor: by room length and width, or by a known area.
- — Set the layer thickness in centimetres — it depends on the substrate and the finish.
- — Copy the coverage and bag weight from the label of the mix you plan to buy.
- — Use area-weighted mean thickness and a chosen reserve; compare volume, dry mass and whole bags.
Method and limitations
- Calculation method
- Formula and logic
- Data or methodology source
- Quick-Step: subfloor drying times are indicative and require moisture checks; dry-mix rate is entered separately
- Limitation
- Water, wet-mix density, reinforcement and strength are not calculated. Drying time and allowed thickness depend on the system and are not determined here.
FAQ
What layer thickness should I use?
Allowed thickness depends on the actual product and floor system, including substrate, loads and construction method. Use its technical documentation and the project. Entering a thickness estimates quantity without establishing that the layer is suitable.
Where do I find the coverage figure?
Use the technical sheet of the actual product. This field expects kg/(m²·cm): multiply a per-1-mm rate by 10; a per-10-mm rate equals a per-1-cm rate.
Why is the number of bags rounded up?
Dry mix is sold in whole bags, so even a small remainder needs one more. Rounding happens after the reserve has been applied.
How much reserve should I add?
First measure mean layer thickness, weighted by the area of each part. Mix reserve is a separate allowance for assumed preparation and placement losses: it increases volume and dry mass before bags are rounded up. It does not correct a wrong thickness or represent a cutting allowance.
Does it split the mix into cement and sand?
No. The estimate is based on a ready dry mix. Cement-to-sand proportions depend on the mortar grade you need and should follow the project or the manufacturer guidance.
Does it work for self-levelling compound?
As a conditional quantity estimate, if the actual product rate can be expressed in kg/(m²·cm) and applies at the chosen thickness. Allowed thickness, substrate, mixing water and application method must be checked separately; the formula does not establish suitability of every dry mix.