Addition Calculator
Add two numbers or a whole list of them, with the working shown. Handles decimals, negatives and very large values without losing precision on screen.
How to use it
- Enter two numbers — the answer updates as you type.
- Switch to the list tab to work through many numbers at once, left to right.
- The working underneath shows the substitution so you can check it by hand.
Examples
| 25 + 17 | 42 |
| 12, 8, 5, 3 | 28 |
Addition combines two or more values into a total. It sounds trivial, but the practical failure points are real: losing track of a running total across a long list, mishandling negative numbers, or losing precision on very large sums. This tool keeps a visible running total and handles decimals and negatives cleanly.
Worked example — adding a list
Reconciling a week's takings of 412.50, 388.20, 501.75, 296.00 and 445.30: the list mode sums all five in one pass to 2,043.75, with each partial total shown as it goes — useful for spotting a typo in one entry rather than only seeing a wrong final figure.
Questions people ask
Can I add more than two numbers?
Yes. Switch to the list tab and paste as many as you like, separated by commas, spaces or new lines.
Is anything sent to a server?
No. Every calculation runs in your browser, so nothing you type is uploaded and the page keeps working offline once it has loaded.
Last updated 22 August 2026