About DevCalcs

What this site is

DevCalcs is a collection of free online calculators covering finance, health, maths, encoding and everyday developer tooling. There are no accounts, no paywalls and no sign-up. Every tool is a single page that does one job.

Each calculator can also be embedded in your own site, either as an iframe or as a web component, so you can drop a working tool into your own pages without rebuilding the maths.

Who builds it

DevCalcs is built and maintained by Waqar Mushtaq. It started as a set of tools I wanted for my own work and grew into a public library. If something is wrong, unclear or missing, I am the person who will read your message — you can reach me at contact@devcalcs.io or via the contact page.

How the calculators are built

Every calculator follows the same pattern, which is what keeps the results consistent as the library grows:

• The maths is separated from the interface. Each calculator's formula lives in its own module with no user-interface code in it, so the calculation can be tested directly.
• Every formula has unit tests. Worked examples are checked against known-good values on every change, so a regression in the maths fails the build rather than reaching the page.
• Formulas are cited. Where a calculator implements a published formula or standard, the authoritative source is linked at the bottom of that calculator's page under References — a regulator, standards body, health authority or specification, not a content farm.
• Nothing you type is sent anywhere. Calculations run entirely in your browser. Your inputs are never transmitted to this site or to anyone else. See the privacy policy for the detail.

Accuracy and its limits

The calculators are built carefully and tested, but they are general-purpose tools working from the numbers you enter. They cannot account for your particular circumstances, and they are not a substitute for advice from a qualified professional — particularly for the finance and health tools. Please read the terms of use, and treat every result as a starting point for a conversation rather than a decision in itself.

If you believe a result is wrong, please tell me. Include the calculator name and the inputs you used and I will look into it.