About CalcYa

Updated in August 2026.

CalcYa started from a simple idea: the calculators people need day-to-day — Spanish VAT, payroll, mortgages — tend to be scattered across sites loaded with aggressive ads, with formulas that are never explained and no indication of where the numbers come from.

This site brings those calculators together in one place, with no sign-up, always showing the formula behind the result along with a worked example so you can check it yourself.

How the calculators are built

Every calculator follows public, standard rules (Spain's general IRPF income tax scale, the French amortization system for loans and mortgages, WHO ranges for BMI, and so on). The calculation code has automated tests that check the results are correct in known cases and don't break on extreme input.

What we don't do

We don't require sign-up or personal data to use the calculators. Nothing you type is sent to any server: the calculations run in your own browser. See the privacy policy for the details.

Missing something or found an error?

If you spot a mistake in a formula or a calculator you'd like to see added, let us know through the contact page.

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