Regex Tester

By CalculatorInn Team · Updated: 2026-03-22 · Free & accurate · Instant results

Test and debug regular expressions against sample text. See all matches, capture groups, and match positions.

Interactive Regex Tester

JavaScript is required for the interactive calculator. Enable JavaScript to use this tool.

How to Use This Calculator

Step-by-Step Instructions

  1. Enter your regex pattern
  2. Enter your test string
  3. Enter your flags
  4. Enter your matches found
  5. Enter your pattern
  6. Enter your match values
  7. Enter your positions
  8. Enter your groups
  9. Enter your error
  10. Results appear instantly — no button needed

Formula

Mathematical Formula

RegExp(pattern, flags).matchAll(testString)

How It Works

RegExp(pattern, flags).matchAll(testString)

Frequently Asked Questions

How does this work?

Enter your values in the fields above and the calculator will compute results instantly using the formula shown.

✦ 600+ free tools — no sign-up required

600+ Free Online Calculators
for Math, Finance, Health & More

Fast, accurate calculators for finance, work, tech, and everyday math. Clear formulas and instant answers.

Free Online Calculators

Browse 600+ free online calculators for finance, math, health, tech, business, education, salary, time, and unit conversions. Instant, accurate results with formulas and worked examples.

Finance Calculators

EMI Calculator Mortgage Calculator Loan Payoff Calculator Compound Interest Calculator Savings Goal Calculator ROI Calculator Break-Even Calculator Credit Card Payoff Calculator Inflation Calculator Net Worth Calculator

Math & Everyday Calculators

Percentage Calculator Fraction to Decimal Calculator Tip Calculator Discount Calculator Profit Margin Calculator Bill Splitter Calculator Markup Calculator Fraction Calculator Square Footage Calculator Concrete Calculator

Health & Fitness Calculators

BMI Calculator Daily Calorie Calculator Body Fat Percentage Calculator Pregnancy Due Date Calculator Macronutrient Calculator TDEE Calculator BMR Calculator Ideal Weight Calculator Protein Intake Calculator Sleep Calculator

Tech & AI Calculators

AI Token Cost Calculator API Pricing Calculator Cloud Storage Cost Calculator Bandwidth Cost Calculator Prompt Token Estimator Hex to Decimal Converter Binary to Decimal Converter Password Strength Checker JSON Formatter Regex Tester

Business Calculators

SaaS Metrics Calculator ROI Calculator Customer Acquisition Cost Calculator Customer Lifetime Value Calculator Revenue Growth Calculator Burn Rate Calculator ARR Calculator Churn Rate Calculator Cloud Cost Calculator Pricing Strategy Calculator

Education & Science Calculators

GPA Calculator Final Grade Calculator Scientific Calculator SAT Score Calculator College GPA Calculator Scholarship Calculator Study Time Calculator Reading Time Calculator Typing Speed Calculator Word Count Calculator

Work & Salary Calculators

Salary to Hourly Calculator Hourly to Salary Calculator Overtime Calculator PTO Calculator Notice Period Date Calculator Freelance Rate Calculator Pay Raise Calculator Paycheck Calculator Take-Home Pay Calculator Commission Calculator

Time & Date Calculators

Age Calculator Date Difference Calculator Time Duration Calculator Retirement Countdown Calculator Time Zone Converter Countdown Calculator Business Days Calculator Pregnancy Due Date Calculator Dog Age Calculator Unix Timestamp Converter

Unit Converters

Length / Distance Converter Weight / Mass Converter Temperature Converter Speed Converter Area Converter Currency Converter Data Storage Converter Pressure Converter Fuel Efficiency Converter Cooking Measurement Converter

Read Calculator Guides & Articles →