About coolca.lc
coolca.lc is a free online calculator for the math people actually do: adding up a receipt, working out a tip, taking a discount off a price, comparing loan payments, converting a recipe. It opens instantly in any browser, on a phone or a computer, with nothing to install and no account to make.
Why it exists
Online calculators tend to fall into two camps. The simple ones are plain to the point of being awkward: no thousands separators, no idea what a dollar is, percentages that don't work the way people expect. The powerful ones bury basic arithmetic under scientific functions, unit menus and ads. coolca.lc aims for the space between: a calculator that's pleasant to use for everyday numbers, and gets the details right.
What makes it different
- Money is a first-class number. Mark a number as money and it's shown with its currency symbol, thousands separators and cents, in your own country's format. Copy a result and it pastes exactly as shown.
- Percentages work the way you say them. 200 + 10% is 220, and the display explains each percentage as it's applied.
- Five Memory presets keep the numbers you reuse, like a tax rate or a price, one tap away.
- The Log keeps your last 100 results to tap and reuse, and undo reaches back hundreds of steps.
- Paste a list and it adds it up, picking the amounts out of receipts, statements and spreadsheets.
- 23 Solvers handle the everyday formulas, like tips, sales tax, discounts, markup and margin, loan payments and unit conversions, solving in any direction.
- Every key has a keyboard shortcut, for fast work at a desk.
Principles
Calculating numbers comes first. Every convenience is designed so it never gets in the way of entering a real-world number.
Your numbers stay on your device. The Log, presets and settings are stored in your browser, not sent to a server. There's no account and no sign-in. See the privacy policy for the details.
Free to use. coolca.lc is supported by advertising and by people who choose to say thanks with a small donation through Buy Me a Coffee.
The Guide
The coolca.lc Guide explains how each feature works and covers the everyday math behind the Solvers: how much to tip, calculating sales tax, markup versus margin, how loan payments work, and more. Every worked example in the Guide was checked against the calculator itself.
Get in touch
Found a bug, have a suggestion, or want to see a new Solver? We'd like to hear from you. See the contact page.