Free Online Converters

Switch between formats, units and notations in a couple of clicks. Every converter here works instantly in your browser — no account, no uploads, and results you can copy straight into whatever you're working on.

Unit Converter

Convert length, weight, temperature and data units instantly — right in your browser.

Roman Numeral Converter

Convert numbers to Roman numerals and Roman numerals back to numbers, with standard subtractive notation and a breakdown of how each numeral is built.

CM to Inches Converter

Convert centimeters to inches (and back) instantly — with common values, the exact formula and a reference table.

KG to LBS Converter

Convert kilograms to pounds (and back) instantly — with common values, the exact formula and a reference table.

Celsius to Fahrenheit Converter

Convert Celsius to Fahrenheit (and back) instantly — with common values, the exact formula and a reference table.

Miles to KM Converter

Convert miles to kilometers (and back) instantly — with race distances, the exact formula and a reference table.

Feet to Meters Converter

Convert feet to meters (and back) instantly — with common values, the exact formula and a reference table.

Liters to Gallons Converter

Convert liters to US gallons (and back) instantly — with common values, the exact formula and a reference table.

Unix Timestamp Converter

Convert Unix timestamps to human dates and back — local time and UTC, in your browser.

Number Base Converter

Convert integers between binary, octal, decimal and hexadecimal with live, error-checked fields.

JSON ↔ YAML Converter

Convert between JSON and YAML in your browser — nothing is uploaded.

JSON ↔ CSV Converter

Convert JSON to CSV and back — handles nested objects, runs in your browser.

Time Zone Meeting Planner

Find a meeting time that works across multiple time zones — a color-coded overlap grid for remote teams.

MM to Inches Converter

Convert millimeters to inches (and back) instantly — with common values, the exact formula and a reference table.

Inches to Feet Converter

Convert inches to feet (and back) instantly — with common values, the exact formula and a reference table.

Yards to Meters Converter

Convert yards to meters (and back) instantly — with common values, the exact formula and a reference table.

Square Feet to Square Meters Converter

Convert square feet to square meters (and back) instantly — with common values, the exact formula and a reference table.

Ounces to Grams Converter

Convert ounces to grams (and back) instantly — with common recipe values, the exact formula and a reference table.

Stone to KG Converter

Convert stone to kilograms (and back) instantly — with common body weights, the exact formula and a reference table.

MG to MCG Converter

Convert milligrams to micrograms (and back) instantly — with common supplement doses, the exact formula and a reference table.

Kilojoules to Calories Converter

Convert kilojoules to calories (and back) instantly — with common food-label values, the exact formula and a reference table.

ML to OZ Converter

Convert milliliters to US fluid ounces (and back) instantly — with common values, the exact formula and a reference table.

Cups to ML Converter

Convert US cups to milliliters (and back) instantly — with common baking fractions, the exact formula and a reference table.

Pints to Liters Converter

Convert US pints to liters (and back) instantly — with common values, the exact formula, a reference table and the UK pint explained.

Acres to Hectares Converter

Convert acres to hectares (and back) instantly — with common land sizes, the exact formula and a reference table.

MPH to KM/H Converter

Convert miles per hour to kilometers per hour (and back) instantly — with common speed limits, the exact formula and a reference table.

Knots to MPH Converter

Convert knots to miles per hour (and back) instantly — with common wind speeds, the exact formula and a reference table.

PSI to Bar Converter

Convert psi to bar (and back) instantly — with common tire pressures, the exact formula and a reference table.

KW to HP Converter

Convert kilowatts to horsepower (and back) instantly — with common car power figures, the exact formula and a reference table.

What you'll find here

Converters for the switches you make every day. The Unit Converter covers length, weight, temperature, volume and more with instant results. The Unix Timestamp Converter translates between epoch seconds and human-readable dates in both directions. And the Number Base Converter moves numbers between binary, decimal and hexadecimal as fast as you can type them.

For structured data, the JSON ↔ YAML Converter and JSON ↔ CSV Converter handle both directions — paste config on one side, copy the other format on the other.

Why these converters are different

Every conversion happens live, locally, in your browser. Nothing you paste is uploaded or logged, which matters when the "value" you're converting is a production API response or a customer export. There's no sign-up wall, no daily limit and no waiting — the result updates as you type.

Popular picks

Scheduling across offices? The Time Zone Meeting Planner finds a slot that works in every city.
The Roman Numeral Converter settles what MCMXCIV actually means — in either direction.
Developers debugging logs live in the Unix Timestamp Converter.

Every converter works in both directions, so you're never stuck translating one way. Pick your converter below and get the answer in one paste.

Frequently asked questions