🔢 Add Commas to Numbers (Number Formatter)
By ToolNimba Editorial Team · Updated 2026-06-19
Enter numbers above to format them.
This number formatter adds commas (or any thousands separator you prefer) to make big numbers easy to read at a glance. Paste a single value or a whole list, one number per line, and choose your grouping style, decimal places and decimal mark. There is also a strip mode that does the reverse, removing existing separators so a number is ready to paste into a spreadsheet, calculator or code. Everything runs in your browser, so your numbers never leave the page.
What is the Number Formatter?
A thousands separator is a small mark placed every three digits to break a long number into readable groups. The number 1234567 is hard to read, but written as 1,234,567 your eye instantly sees roughly one and a quarter million. The grouping always starts from the right of the whole-number part and works left in groups of three, so the leftmost group can have one, two or three digits. The fractional part after the decimal mark is never grouped this way.
Different regions use different marks, which is the main source of confusion. The United States, the United Kingdom and most English-speaking countries use a comma for thousands and a point for the decimal, so 'one thousand two hundred and thirty four, and a half' is written 1,234.5. Much of continental Europe swaps them, writing 1.234,5 with a period for thousands and a comma for the decimal. Others, including the SI/metric standard and countries like France and Sweden, use a thin space (1 234,5), and Switzerland traditionally uses an apostrophe (1'234.5). This tool lets you pick the grouping character and the decimal mark independently so you can match any of these conventions.
The formatting is purely cosmetic: it changes how a number looks, not its value. That matters when you move numbers between tools. A spreadsheet, programming language or database usually wants a plain number with no grouping (and a point as the decimal), so a value displayed as 1,234.50 must be stripped back to 1234.50 before it will parse. The strip mode here does exactly that, removing commas, spaces, periods and apostrophes used as group marks while preserving the decimal portion exactly as entered, so you can round-trip numbers between human-friendly and machine-friendly forms.
When to use it
- Formatting figures in a report, invoice or slide so large amounts like 1,250,000 are instantly readable.
- Cleaning a column of numbers that already contain commas so they can be pasted into a spreadsheet or imported as plain values.
- Switching a list between US style (1,234.56) and European style (1.234,56) for an international document.
- Standardising prices, populations or statistics to a fixed number of decimal places before publishing.
- Preparing numbers for code or a CSV where grouping characters would break parsing.
How to use the Number Formatter
- Enter your numbers in the box, either a single value or one number per line.
- Pick Add separators to format, or Strip separators to remove them.
- Choose the thousands separator (comma, space, period or apostrophe) and the decimal mark.
- Optionally set a fixed number of decimal places, the tool rounds for you.
- Read the formatted list in the result box and use Copy to grab all of it.
Formula & method
Worked examples
Format 1234567 with comma grouping and a point decimal mark.
- There is no decimal part, so all seven digits are whole-number digits.
- Group from the right in threes: 567, then 234, then 1.
- Join the groups with commas: 1 , 234 , 567.
Result: 1,234,567
Format 9876.5 to 2 decimal places, US style.
- Split into whole part 9876 and fraction 5.
- Round the fraction to 2 places: 5 becomes 50, giving 9876.50.
- Group the whole part in threes: 9 , 876.
- Add the decimal mark and the two fraction digits: 9,876.50.
Result: 9,876.50
Strip the separators from 1.234.567,89 (European style) for a spreadsheet.
- The last mark followed by digits is the comma before 89, so that is the decimal mark.
- Remove every grouping period from the whole part: 1234567.
- Keep the fraction and use a plain point: 1234567.89.
Result: 1234567.89
How the same value is written in different regional conventions
| Convention | Thousands mark | Decimal mark | Example (1234567.89) |
|---|---|---|---|
| US / UK | Comma | Point | 1,234,567.89 |
| Many EU countries | Period | Comma | 1.234.567,89 |
| SI / metric | Thin space | Comma or point | 1 234 567,89 |
| Switzerland | Apostrophe | Point | 1'234'567.89 |
| Plain (for code) | None | Point | 1234567.89 |
Grouping examples by number size (comma style)
| Plain number | Formatted | Word value |
|---|---|---|
| 1000 | 1,000 | One thousand |
| 25000 | 25,000 | Twenty-five thousand |
| 1000000 | 1,000,000 | One million |
| 1234567890 | 1,234,567,890 | About 1.23 billion |
Common mistakes to avoid
- Mixing up the thousands and decimal marks. In the US a comma groups thousands and a point is the decimal, but in much of Europe it is the opposite. Reading 1.234 as one and a bit when it means one thousand two hundred and thirty four (or the reverse) causes real errors. Always confirm which convention a number uses before formatting or stripping it.
- Leaving commas in numbers meant for a spreadsheet or code. A value like 1,234.50 is text to most software because of the comma. Pasting it into a spreadsheet cell or a program can break the math or import it as a string. Use strip mode to get the plain 1234.5 first.
- Grouping the digits after the decimal point. Thousands separators apply only to the whole-number part. The fractional digits are never split into groups of three, so 0.123456 stays as 0.123456, not 0.123,456.
- Assuming formatting changes the value. Adding separators is purely visual. 1,000 and 1000 are the same quantity. The only step that can change the value here is choosing fixed decimal places, which rounds the number.
Glossary
- Thousands separator
- A mark (comma, space, period or apostrophe) placed every three digits in the whole-number part to make a long number easier to read.
- Decimal mark
- The symbol that separates the whole part of a number from its fractional part, a point in US style and a comma in much of Europe.
- Digit grouping
- The practice of breaking the integer part of a number into blocks of three digits, counting from the right.
- Strip
- Removing all grouping separators from a number so it becomes a plain value ready for software or further calculation.
- Rounding
- Shortening a number to a chosen number of decimal places, adjusting the last kept digit up or down based on the digit that follows.
Frequently asked questions
How do I add commas to a number?
Paste your number into the box and keep the mode on Add separators with the comma option selected. The tool inserts a comma every three digits from the right of the whole-number part, so 1234567 becomes 1,234,567. You can format a whole list at once by entering one number per line.
Can I use a space or a period instead of a comma?
Yes. The thousands separator menu lets you choose a comma, a space, a period or an apostrophe, and you can set the decimal mark to a point or a comma independently. That covers US (1,234.56), European (1.234,56), metric (1 234,56) and Swiss (1’234.56) styles.
How do I remove commas from numbers?
Switch the mode to Strip separators. The tool removes commas, spaces, periods and apostrophes that act as grouping marks while keeping the decimal part, turning 1,234.50 back into 1234.50 so it is ready for a spreadsheet or code.
Does formatting change the actual number?
No. Separators are purely cosmetic and the value is unchanged, so 1,000,000 equals 1000000. The only setting that alters the value is choosing a fixed number of decimal places, which rounds the number to that many places.
Can I round to a set number of decimal places?
Yes. Use the decimal places menu to fix the output to 0, 1, 2, 3, 4 or 6 places. The tool rounds correctly, including carrying over, so 9999.96 to one place becomes 10,000.0. Leave it on "Keep as entered" to preserve the original decimals.
Is my data sent anywhere?
No. All formatting happens locally in your browser using plain JavaScript. Nothing is uploaded, logged or sent over the network, so you can safely format sensitive figures like salaries or financial data.