28 free tools · 25 site calculators plus HAV, 6×6 risk & accreditation · no sign-in · guidance only
All 28 tools
Masonry · coats · sand · cement
How much sand and cement for render?
Two or three coat render by area, with the beads and mesh that get left off the order. Set a coat to zero if you are not using it.
1
Measure it
Every box has its own unit next to it.
Change the unit beside any box and the number converts. The (i) beside each question says what the box wants and where the figure usually comes from. Anything marked per cent is a percentage of the quantity above it.
2
Check the rates
Rates and assumptions used
These are the figures the calculator works to. Change any of them and the order list updates — your merchant’s pack sizes and your own waste allowances beat the defaults every time.
How this one works
Total thickness = scratch + float + top
Volume = net area × total thickness × (1 + waste %)
Dry volume = wet × 1.3, split by the mix ratio
Each coat should be weaker than the one behind it, or it cracks
The figures the calculator works to. Every one can be changed in step 2, and your merchant’s pack sizes and your own waste allowances beat these defaults every time.
Rate
Default
Why
Sand density
1.6 t/m³
Dry-to-wet factor
1.3
Cement bag
25 kg
Bead length
2.5 m
Render mesh roll
50 m²
A worked example
With the defaults the page opens on:
How long is the wall? 10 metres
How tall is it? 5 metres
Doors and windows to take off? 5 square metres
How thick is the scratch coat? 12 millimetres
How thick is the float coat? 10 millimetres
How thick is the top coat? 6 millimetres
Which mix? 5:1 — general render
Spare for waste 10 per cent
Render
Net area: 45 m² — L × H − openings
Total thickness: 28 mm — scratch + float + top
Waste allowance: 10 %
Volume: 1.39 m³
Rendering sand: 0.28 t— mix 5:1
Cement: 3 bags— 57 kg
Waterproofer: 1 × 5 L — one to four bags, scratch coat only
Beads & mesh
Stop / bellcast bead: 8 × 2.5 m — base and head of the render
Angle bead: 4 × 2.5 m — external corners
Render mesh: 1 rolls — over dissimilar backgrounds and every joint
Change any figure above and every line recalculates; the small print under each row is the sum that produced it.
Questions people ask
How much sand and cement for render?
Net area × total thickness × waste, then ×1.3 for the dry materials, split by the ratio. A 10 m × 5 m wall less 5 m² of openings at 28 mm total needs about 1.7 t of rendering sand and 14 bags of cement at 5:1.
What thickness is each coat?
The defaults are 12 mm scratch, 10 mm float and 6 mm top. Set the float coat to 0 for a two-coat job.
Should every coat be the same mix?
No - each coat should be weaker than the one behind it or it cracks. The calculator uses one ratio for the whole thickness; run it once per coat if you are mixing them differently.
What beads do I need?
Stop or bellcast bead along the base and head, angle bead on every external corner, and mesh over dissimilar backgrounds and joints. The calculator counts them in 2.5 m lengths.
Read before you order. These work out quantities, not structural design — spans, lintels, rebar and foundation depths need an engineer and Building Control sign-off. Waste allowances are defaults, not promises: awkward cuts, long runs and bad weather all eat more than 5%. Where a merchant sells whole packs, the figure is rounded up to whole packs.
