CONCRETE MIX DESIGN

BS 8500 / EN 206 Concrete Mix Design Calculator

Calculate a transparent preliminary concrete mix to EN 206 with the BS 8500 national annex — pick a strength class and an exposure class, and see the durability limiting values behind the mix. Then buy a detailed £4.99 calculation report for your files.

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Build a mix you can actually check

Design Mix Concrete works through proportioning by the absolute-volume method and shows the calculation trail at each step — not just a final number. Alongside the strength-based design it shows the BS 8500 durability limiting values for your chosen exposure class: maximum water-cement ratio, minimum cement content, minimum strength class and, where relevant, minimum air content for freeze-thaw resistance. Results are preliminary: always verify against the current BS 8500 / EN 206 editions, the project specification, material test data and trial batches before use.

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Useful for C20/25 to C40/50

Start from a typical strength class as a reference point, then enter the actual specified class, exposure class and target slump for your project.

C25/30 concreteTypical use and exposure C32/40 concreteTypical use and exposure C40/50 concreteTypical use and exposure Custom classEnter your own strength and exposure class

Key tools

CalculatorFull EN 206 mix design with strength class, exposure class and a calculation trail MethodThe EN 206 proportioning method, step by step ClassesC20/25 to C50/60 reference Cost calculatorEstimate material cost per m³

Frequently asked questions

Which standard does this use?

Proportioning follows EN 206 with the BS 8500 national annex, which sets the durability limiting values used in the UK — maximum water-cement ratio, minimum cement content, minimum strength class and minimum air for freeze-thaw — against each exposure class.

Is it free?

Yes. Design Mix Concrete is free to use and supported by advertising. The £4.99 report is optional.