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+$

Token	Meaning
^	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

3 matches· capture groups: 1

Test Cases

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

Input	Expected	Result
		Pass
		Pass
		Pass
		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

Engine	Supported	Notes
Chrome	Yes	—
Firefox	Yes	—
Safari	Yes	—
Edge	Yes	—
Node.js	Yes	—

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