Cinder Block Calculator
Standard CMU is 440×215mm (UK) / 8×8×16in (US) — count blocks by wall area.
Result
Net wall area18 m²
Blocks needed189
Mortar (25kg bags)6
Courses high8
Cinder Block Calculator — FAQs
How many blocks per m²?
UK 440×215mm blocks: 10/m². US 8×8×16in: 12.5/yd²... roughly — always add 5% for cuts and breakages.
How much mortar?
A 25kg bag lays ~30–40 blocks. Thicker beds and hot weather push it toward the low end.
Need a Custom Tool Built?
We build calculators, estimators and internal tools for businesses in the UK and North America.
Get a QuoteEmbed this Cinder Block Calculator on your site
Free to use — paste this snippet into any webpage. It auto-resizes and includes a small attribution link. Add ?theme=dark to the iframe URL for dark mode.