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HardNumbers5 min read

Scientific Notation Regex

Validates a number written in scientific (exponential) notation, such as 1.23e-10 or -6.022E23, with a mantissa, an e/E marker, and a signed integer exponent.

#scientific-notation#numbers#exponent#validation#floating-point

Regex Pattern

^-?\d+(\.\d+)?[eE][+-]?\d+$

Pattern Breakdown

Hover over a token to see what it does.

^-?\d+(\.\d+)?[eE][+-]?\d+$
TokenMeaning
^Anchors the match to the start of the string.
-?An optional leading minus sign for a negative mantissa.
\d+One or more digits for the integer part of the mantissa.
(\.\d+)?An optional fractional part of the mantissa, a dot followed by one or more digits.
[eE]The literal exponent marker, lowercase e or uppercase E.
[+-]?An optional sign on the exponent, defaulting to positive when omitted.
\d+One or more digits for the exponent value.
$Anchors the match to the end of the string.

Detailed Explanation

What it does

This pattern matches numbers written in scientific notation: a mantissa (an integer or decimal number, optionally negative) followed by an e or E marker and a signed or unsigned integer exponent. Examples include 1e10, 1.23e-10, and -6.022E23. Plain numbers without an exponent marker are rejected.

Why it works

The mantissa is built the same way as a general number, with a required integer portion and an optional `(\.\d+)?` fractional portion, so both whole-number and decimal mantissas are supported. The `[eE]` class accepts either letter case used for the exponent marker, and `[+-]?\d+` requires at least one exponent digit while allowing an explicit sign. Anchoring both ends ensures the exponent marker isn't optional or missing, which is what distinguishes this from a plain decimal number.

Common use cases

  • Validating numeric literals in a data file or scientific dataset that uses exponential notation
  • Parsing measurement values from instruments or APIs that report very large or very small magnitudes
  • Pre-checking user input in a scientific or engineering calculator application
  • Detecting scientific notation in text before converting it with a numeric parser

Edge cases

  • 1e10 matches even without a fractional mantissa or explicit exponent sign, since both are optional
  • 1.5E+10 matches with an uppercase marker and an explicit positive exponent sign
  • 1e (a marker with no exponent digits) correctly fails since at least one exponent digit is required
  • 10 (no exponent marker at all) correctly fails, distinguishing it from a plain decimal number

Limitations

  • Does not accept a fractional exponent, since real-world exponential notation always uses an integer exponent
  • Does not validate that the resulting numeric value fits within a particular floating-point precision or range
  • Does not accept alternative notations like 1x10^10 that some non-programming contexts use for scientific notation

Interactive Tester

Edit the pattern or text below — matching runs live in your browser.

//
Open in Playground →
1e10 1.23e-10 -6.022E23

Test Cases

Editable — add your own inputs to see if they pass.

InputExpectedResult
Pass
Pass
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Pass

Language Variants

Production-ready examples in 12 languages.

const scientificPattern = /^-?\d+(\.\d+)?[eE][+-]?\d+$/;

function isScientificNotation(value) {
  return scientificPattern.test(value);
}

console.log(isScientificNotation("1.23e-10")); // true

Common Mistakes

Making the exponent digits optional, which would let a bare 'e' with no digits incorrectly match.

Fix: Keep `\d+` (one or more) for the exponent, not `\d*`, so at least one exponent digit is required.

Forgetting that a mantissa without a fractional part, like 1e10, is perfectly valid scientific notation.

Fix: Keep the fractional mantissa group optional with `(\.\d+)?` rather than requiring it.

Only matching lowercase 'e', missing values that use an uppercase 'E' marker.

Fix: Use the character class `[eE]` to accept either case.

Performance Notes

  • All groups use bounded, non-overlapping quantifiers, so the pattern matches in linear time with no catastrophic backtracking.
  • Anchoring both ends lets malformed input, like a missing exponent marker, fail immediately.
  • The optional fractional-mantissa group is checked before the mandatory exponent, so integer-mantissa values like 1e10 skip that branch quickly.

Browser Compatibility

EngineSupportedNotes
ChromeYes—
FirefoxYes—
SafariYes—
EdgeYes—
Node.jsYes—