Sand & cement mortar calculator
Pick the ratio and tell it the wall area or the mortar volume you need. It returns 25 kg cement bags and sand in tonnes or bulk bags, with waste. Good for laying, repointing and bedding.
Mortar volume
0.000 m³
Includes 30% for voids and joints
Cement (25kg bags)
0 bags
Sharp sand
0 kg
~1 bulk bag = 800kg
Always mix dry before adding water. Use plasticiser not washing-up liquid. Discard any mix unused after 2 hours.
Pricing the job? Open EstiMate free and these quantities go straight onto the materials list with your prices.
How it works out the quantities
- 1Brickwork uses about 0.02–0.03 m³ of mortar per m² of half-brick wall; blockwork about 0.01 m³ per m².
- 2The ratio sets the cement share: 1:5 means one part cement to five parts sand by volume. Denser mixes (1:3) are for below DPC, copings and pointing in exposed positions.
- 3Cement is converted to 25 kg bags (about 1,400 kg/m³ bulk density) and sand to tonnes (about 1,600 kg/m³).
- 4Waste of 10–15% is normal for mortar because of dropped and dried material.
Site tips before you order
- Use building (soft) sand for laying and pointing; sharp sand for bedding slabs and screed.
- Add plasticiser rather than extra water to improve workability — it keeps the strength.
- In cold weather keep sand covered and don't lay below 3 °C and falling.
- Lime mortars for older properties behave differently; the calculator's bag counts are for cement mortars.
Common questions
What mortar ratio for brickwork?
1:5 or 1:6 cement:sand for general facing brickwork above DPC, 1:4 for blockwork and semi-exposed work, 1:3 below ground and for copings.
How much sand and cement per m² of brickwork?
About 25–30 kg of mortar per m² of half-brick wall — roughly 4–5 kg cement and 22–25 kg sand at 1:5, before waste.
How many bags of cement in a bulk bag of sand?
A bulk bag is roughly 0.5 m³ / 800 kg of sand. At 1:5 that's about 6 bags of cement; at 1:4, 7–8 bags.
Can I use this for repointing?
Yes — enter the mortar volume directly (joint depth × joint width × total joint length) and it gives the bags and sand.
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