Percentage Value Regex for Go

What this pattern does

This page provides a well-structured, multi-part regular expression for matching percentage value, ported and verified for Go. Financial data validation has zero tolerance for false negatives — a missed invalid entry can corrupt downstream calculations. The snippet below is ready to drop into your Go project — whether you're validating in a Gin handler, a gRPC service, or a command-line tool.

Go Implementation

// Percentage Value
// ReDoS-safe | RegexVault — Finance > Currency & Money

package validation

import "regexp"

var percentageValueRe = regexp.MustCompile(`^-?(?:100(?:\.0{1,4})?|(?:[0-9]{1,2}(?:\.[0-9]{1,4})?))%?$`)

func ValidatePercentageValue(s string) bool {
    return percentageValueRe.MatchString(s)
}

// Example
// fmt.Println(ValidatePercentageValue("0")) // true

Test Cases

When to use this pattern

This pattern is drawn from the Finance > Currency & Money category and carries a ReDoS-safe certification. That matters for Go developers because Go's RE2 engine is inherently safe from catastrophic backtracking, but this pattern has been additionally verified for correctness. RegexVault audits patterns against known backtracking attack vectors, ensuring you have the necessary context before using this regex in a high-stakes production environment.

Common Pitfalls

Technical Notes

Constrained to -100 to 100. For percentages that can exceed 100% (e.g., year-over-year growth), remove the upper bound: ^-?[0-9]+(?:\.[0-9]{1,4})?%?$ . The percent sign is optional for API input.