Floor Screed Calculator
Calculate exactly how much sharp sand and cement you need for a floor screed. Free materials estimator.
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How to Calculate Floor Screed Materials
Unlike poured concrete which contains large aggregates (gravel), a floor screed is a semi-dry mixture of only sharp sand, cement, and a minimal amount of water. Because it is mixed on-site, you need to calculate the raw weight of materials to order.
The industry standard density for mixed floor screed is 2,000 kg per cubic meter. First, find your floor's volume in cubic meters. Then multiply by 2,000 to find the total weight. Finally, divide that total weight according to your mix ratio (usually 1:4) to determine how many 25kg bags of cement and tonnes of sand to order.
Screed Mix Ratios Explained
1:4 Ratio (Standard)
1 part cement to 4 parts sharp sand. This is the universally accepted standard mix for domestic internal floor screeds laid over insulation or damp proof membranes.
1:3 Ratio (Strong)
1 part cement to 3 parts sharp sand. Used for heavy traffic areas, commercial floors, or when a screed must be laid thinner than standard minimums.
Frequently Asked Questions
What is the best mix ratio for floor screed?
The standard and most common mix ratio for a domestic floor screed is 1:4 (1 part cement to 4 parts sharp sand). For heavy traffic areas or thinner bonded screeds, a stronger 1:3 ratio is recommended.
How much does a cubic meter of screed weigh?
A standard dry-pack semi-dry floor screed weighs approximately 2,000 kg (2 tonnes) per cubic meter once mixed with the appropriate amount of water.
What is the minimum thickness for a floor screed?
For an unbonded screed (laid over a damp proof membrane), the absolute minimum thickness is 50mm. For a fully bonded screed (adhered directly to the concrete base with a primer), it can be laid as thin as 25mm to 40mm.
What type of sand is used for screed?
Screed requires coarse sharp sand (sometimes called grit sand or concreting sand). You cannot use soft building sand (mason's sand) because it lacks the angular structure needed for strength and will shrink too much as it cures.