Unit Converters

Quick daily-life calculators: dates, times, travel budgets, tips and currency conversions.

Temperature Converter

Convert between Celsius, Fahrenheit and Kelvin instantly with the exact SI-defined formulas, showing all three scales at once.

Convert length between millimeters, centimeters, meters, kilometers, inches, feet, yards and miles using exact NIST/international definitions.

Convert weight/mass between milligrams, grams, kilograms, tonnes, ounces, pounds and stone using exact avoirdupois definitions.

Convert speed between kilometers per hour, miles per hour, meters per second and knots using exact SI and nautical-mile definitions.

Convert area between square meters, square kilometers, square feet, acres and hectares using exact NIST and international-foot definitions.

Convert volume between milliliters, liters, cubic meters, US gallons, UK gallons, US cups and US fluid ounces with exact legal definitions.

Convert numbers to Roman numerals or Roman numerals to numbers (1–3999), using standard subtractive notation with strict validation.