How Much Sand and Cement Do I Need? A UK Quantities Guide
Published 2026-07-13 · Browse all tools
"How much sand and cement do I need?" is one of those questions where the honest first answer is "it depends" — on the job, the mix, and the depth or area you're covering. But the method behind it is the same every time, and once you've seen it you can size a mortar batch, a floor screed or a small concrete pour without guessing. This guide walks through it for the three jobs that eat most of a UK builder's sand and cement.
Two of these have a calculator that does the arithmetic for you: the screed calculator and the mortar calculator. This explains what they're doing and how to sanity-check the numbers.
Use the Mortar Calculator hereThe method, once
Every sand-and-cement job follows the same four steps:
- Work out the volume. Area × depth for screed and concrete; wall area or unit count for mortar.
- Add wastage. Spillage, over-dig, the odd deep patch. 10% for screed, 15% for mortar.
- Allow for compaction. Loose dry materials take up more room than the finished, compacted result — multiply by about 1.3 to get what you actually buy.
- Split by the ratio. Divide the dry materials into cement and sand by the mix ratio, then convert to 25 kg cement bags and tonnes of sand.
Mortar for brickwork
Bricklaying mortar is a cement-and-sand (usually soft sand) mix, commonly 1:5 above the damp-proof course.
A rough anchor: 1,000 standard bricks needs about 8 bags of cement and a tonne of sand at 1:5, wastage included. Per square metre of single-skin wall (around 60 bricks), that's roughly 0.03 m³ of mortar.
So for a typical 10 m² garden wall — about 600 bricks — you're looking at around 5 bags of cement and just over half a tonne of sand. Drop to a 1:3 mix below ground and the cement goes up; a 1:6 internal mix uses less.
Sand and cement for floor screed
A traditional floor screed is a stiffer, sharp-sand mix, usually 1:4 (cement to sharp sand), laid over a slab or insulation.
Screed is genuinely cement-hungry compared to what people expect. A 25 m² floor at 75 mm and 1:4 needs roughly 31 bags of cement and 3.4 tonnes of sharp sand — that's about one 25 kg bag of cement and 0.14 tonnes of sand per square metre.
Use sharp sand, never soft building sand for screed. Soft sand makes a weak, dusty floor that breaks up.
Sand, cement and aggregate for small concrete
Concrete adds coarse aggregate (gravel) to the sand and cement, typically in a 1:2:4 mix (cement : sharp sand : aggregate) for general work, or 1:1.5:3 for stronger structural concrete.
For anything more than a small patch, ready-mixed or bagged concrete is usually easier and cheaper than batching by hand. A standard 20 kg bag of pre-mixed concrete yields only about 0.009 m³, so a modest 1 m³ pour is over 100 bags — which is exactly when a ready-mix truck starts to make sense.
Buying tips that save money
- Bulk bags beat small bags on anything but tiny jobs. A bulk (dumpy) bag of sand is far cheaper per tonne than the same weight in 25 kg bags, though bulk bags vary from about 800 kg to a tonne, so check the weight before comparing prices.
- Buy cement fresh and keep it dry. Cement has a shelf life and hates damp — lumpy, part-set cement is weaker. Only buy what you'll use in a few weeks.
- Order one bulk bag of sand spare rather than running short mid-job. Returning an unopened bag is easier than a second delivery charge.
- Prices move. In 2026, budget roughly £5–£6 for a 25 kg bag of cement and £50–£55 for a bulk bag of sand at merchants like Travis Perkins, Jewson or Selco, but check on the day.