About Reckon
Reckon is a lightweight, distraction-free calculator built for quick everyday sums — bills, totals, discounts, and back-of-envelope math — right inside this page. No app to install, no sign-up, no ads inside the tool itself. Just open the page and start calculating.
Features
- Standard arithmetic: addition, subtraction, multiplication and division
- One-tap percentage conversion for quick discount and tax math
- Backspace key to correct a single digit without clearing everything
- Running history line shows the last expression above the result
- Full keyboard support — type numbers and operators directly
- Works entirely in your browser; no data is stored or sent anywhere
How to use it
- Tap the number keys to enter your first value.
- Choose an operator: ÷, ×, − or +.
- Enter the second value, then tap the red = key for the result.
- Use ⌫ to remove the last digit, or C to clear everything and start over.
- Tap % right after a number to convert it to its percentage value.
- On a computer, you can also type directly using your keyboard's number and operator keys, and press Enter for =.
Frequently asked questions
Does Reckon save my calculations?
No. Everything happens locally in your browser tab. Nothing is saved, stored, or sent to a server, so your history disappears once you refresh or leave the page.
Can I use my keyboard instead of tapping?
Yes. Number keys, +, -, *, /, the decimal point, Enter (for equals), and Backspace all work the same as the on-screen buttons.
What happens if I divide by zero?
Reckon will show an error on the display in red. Tap C to clear it and start a fresh calculation.
Is there a limit to how large a number I can enter?
Reckon handles typical everyday numbers comfortably. For very large results, the display will switch to scientific notation to keep the number readable.
Does this work on mobile?
Yes, the layout and buttons resize automatically for phones and tablets, so it works the same way on any screen size.