Number Validator
Enter a decimal number to check its syntax, finiteness, and supported range in your browser.
ASCII digits, optional sign, decimal point, and exponent; range −1e100 to 1e100.
A QUICK WALKTHROUGH
How to use this tool
- Enter one decimal number, optionally with a sign, decimal point, or exponent.
- Use ASCII digits and no grouping separators; surrounding whitespace is ignored.
- Review the syntax and range result.
Explicit syntax and bounds
Accepted input is an optional + or − sign, a decimal mantissa with at least one digit, and an optional e or E exponent with an optional sign. Surrounding whitespace is trimmed; commas, underscores, hexadecimal notation, Infinity, and NaN are rejected. Inputs are limited to 128 characters and the finite numeric value must be between −1e100 and 1e100.
Local validation only
The check runs in your browser and does not look up units, locale formats, or external data.
GOOD TO KNOW
Common questions
Are commas or locale digits accepted?
No. Use ASCII digits and a dot for the decimal point; grouping separators and locale-specific digits are rejected.
Does valid mean exact arbitrary precision?
No. The result uses the browser Number type, so very long values may be rounded. It only confirms the documented syntax, finiteness, and range.