A calculator library that shows its working
Calcora brings 33 everyday calculators into one clean, fast site across 4 categories. It exists because most calculator pages online either bury the formula, hide the answer behind a sign-up, or both.
Formulas from the source
Each calculator implements a standard published method — Mifflin-St Jeor for basal metabolic rate, the annuity formula for loans, Naegele's rule for due dates — and names it on the page so you can check the working.
Every answer explained
A number on its own is not much use. Each tool shows the inputs it used, a line-by-line breakdown, the formula behind it and a worked example you can follow by hand.
Nothing collected
Calculations run in your browser. Salaries, weights and balances are never transmitted, logged or stored — refresh the page and they are gone.
Free, and honestly so
The site is funded by advertising rather than subscriptions, which is why there is no account wall. Ads are placed away from input fields so they never get in the way of a calculation.
How the site is built
Every calculator is a self-contained page with its own address, unique description and structured data, so it can be found, linked and shared directly. The site is designed to work at any screen size, loads without heavy scripts, and keeps the input fields large enough to tap comfortably.
Get in touch
Spotted an error, or need a calculator that is not here yet? Email hello@calcora.example. Corrections to a formula are treated as a priority.