Numeric rounding and formatting
Round exact decimal input to decimal places or significant digits, or write scientific notation.
- 1Add input
- 2Adjust settings
- 3Get your result
Tool input and files are processed in this browser without being uploaded.
Before you start
Round one decimal number with a clear tie rule. Choose fixed decimal places, significant figures, or scientific notation. Negative places round to tens and larger powers of ten.
How to use this tool
- Enter one number, then choose decimal places, significant figures, or scientific notation.
- Set the number of places or significant digits and choose a rounding rule. Inspect the live preview.
- Format the number, then copy the result or download it as text.
Supported inputs and limits
Accepts up to 300 decimal digits and exponents from −300 to 300. Decimal places range from −12 to 100; significant digits from 1 to 100.
Uses decimal-string arithmetic, not binary floating-point conversion. Match the tie rule used by your target system.
Input is processed in this browser. No account is needed.
Worked example
Example input
1.005
Example options
{"places":2,"mode":"half-up"}Example output
1.01
When something does not work
If the output differs from your target application, check its halfway rule and whether it rounds decimal input or a binary floating-point value.
Frequently asked questions
Why does 1.005 round differently in some apps?
Some apps first convert decimal text to a binary floating-point number. This tool rounds the entered decimal value directly, so 1.005 with two places and halfway-away-from-zero gives 1.01.
How do I round to the nearest ten or hundred?
Choose Decimal places and enter −1 for tens or −2 for hundreds.
How are negative halfway values handled?
Halfway away from zero sends −1.5 to −2. Halfway to even sends it to −2; floor, ceiling and truncation follow their named directions.
Is my input sent to a server?
No. This tool processes input in your browser. Save the output before closing the tab.
Documentation & further reading
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