About Calcly

A free, sign-in-free library of 230+ calculators for the decisions people actually make — mortgages, taxes, training plans, scientific math, and the long tail of everyday quantities.

Why Calcly

The web is full of calculators that bury inputs under ads, hide assumptions, or quietly use stale tax tables. Calcly exists because we wanted a single place where the numbers are right, the formulas are legible, and you can share a result by URL without signing up.

Every calculator runs entirely in your browser. There is no server-side computation, no account, and no behavioural tracking. State lives in your URL or in your browser's local storage — when you delete the site data, everything is gone.

How we build

• Source-of-truth formulas. The math behind each calculator is documented on the page, including the formulas, the variables, and (where relevant) the year and jurisdiction it applies to. The methodology page covers our review and update cadence in detail.
• Tested. Tax engines, financial primitives, and shareable-URL serialization are covered by an automated test suite that runs on every change.
• Accessible. WCAG-conformant focus rings, AAA-grade contrast, full keyboard navigation, screen-reader-friendly result regions, and a mobile-first sticky action bar.
• Open about updates. Every calculator page surfaces a last-updated date drawn from the git commit history — no stale tax tables hiding under a 2018 timestamp.

What we don't do

• We don't require an account.
• We don't sell or share user-level data.
• We don't give legal, tax, medical, or investment advice — we give you a precise calculation and the formula it's based on.

Get in touch

Spot a number that looks wrong, want a calculator we don't have, or want to embed one of ours? Contact us.