Free calculators for UK trades

These run entirely in your browser. Nothing you type is sent anywhere or stored, and there is no signup, no email capture and no limit on how often you use them.

Both cover the two calculations that cause the most trouble on trades invoices. CIS trips people up because the deduction applies to labour and not to materials, so applying it to the invoice total quietly costs the subcontractor real money. VAT trips people up in the other direction, because working backwards from a VAT-inclusive figure means dividing by 1.2 rather than taking 20% off, and taking 20% off gives an answer that is wrong by a few percent every single time.

A note on accuracy

These calculators do the arithmetic correctly, but they cannot tell you which VAT rate applies to your job or whether your customer counts as an end user for the reverse charge. Construction VAT is genuinely complicated — new-build residential work is often zero rated, some renovation work qualifies for 5%, and a lot of business-to-business construction work shifts the VAT onto the customer entirely. Check the treatment before you invoice, and read the guides below if you are not sure.