Online Calculators — Percentage, Unit Converter and More
Free calculators for percentages and everyday maths, plus unit converters for length, weight, temperature and more, and number-to-words and Roman numerals.
- Scientific Calculator A scientific calculator you can type a whole expression into or tap with the keypad.
- Percentage Calculator Five percentage questions in one place, each answered as you type — from finding 15% of a price to working out the original price before a discount.
- Statistics Calculator Paste scores, sales figures or measurements separated by commas, spaces or new lines.
- Unit Converter Convert any measurement in one place.
- Fraction Calculator Enter two fractions, pick an operation and get the simplified answer with every step shown — common denominator, numerators, simplifying and the mixed number.
- Length Converter Convert heights, distances and dimensions between metric and US units — centimetres to inches, feet to metres, miles to kilometres and more.
- GCF and LCM Calculator Enter two or more whole numbers to get their greatest common factor (GCF, also called GCD or HCF) and least common multiple (LCM).
- Paper Sizes Chart How big is A4, and how many pixels is it at 300 DPI?
- Weight Converter Convert body weight, parcel weight or recipe amounts between metric and US units — kilograms to pounds, ounces to grams, stones to kilograms and more.
- Fuel Economy and Trip Cost Calculator Convert mpg to litres per 100 km and back, and budget a road trip.
- Prime Factorization Calculator Enter a whole number to see its prime factorization in exponent form, such as 360 = 2³ × 3² × 5, drawn as a factor tree.
- Temperature Converter Convert oven, weather and body temperatures between Celsius and Fahrenheit, or scientific values in Kelvin, as you type.
- GPA Calculator Enter each course's credits and grade to get your credit-weighted GPA.
- Quadratic Equation Solver Enter a, b and c to solve ax² + bx + c = 0.
- Grade Calculator Enter your scores and how much each one counts to get your current weighted grade.
- Number to Words Converter Spell out any number in English for cheques, contracts, invoices or essays.
- Ratio Calculator Three ratio tools in one.
- Average Calculator Paste a list of numbers to get the average (arithmetic mean) with the working shown, plus the median, mode, count, sum and range.
- Roman Numeral Converter Type a number to see it in Roman numerals, or type Roman numerals to get the number.
- Font Size Converter Convert a font size between points (pt), CSS pixels (px), em/rem, percent and millimetres — for moving designs from Word or print to CSS and back.
- Area Calculator Pick a shape, enter its dimensions and get the area and perimeter immediately.
- Volume Calculator Pick a solid, enter its dimensions and get the volume and surface area immediately.
- Triangle Calculator Enter any three known values of a triangle, including at least one side, and get the missing sides and angles, the area, the perimeter and whether it is acute, right or obtuse.
- Aspect Ratio Calculator Enter the width and height of an image, video or screen to get its simplest aspect ratio and the nearest common ratio.
- Area Converter Convert the area of a room, a house or a plot of land between metric and imperial units — square feet to square meters, acres to hectares and more — with every unit listed at once.
- Volume Converter Convert volume and capacity between liters, milliliters, cubic meters, gallons, fluid ounces, cups and spoons — for recipes, fuel and tank sizes — with every unit listed at once.
- Speed Converter Convert speed between km/h, mph, m/s and knots — speed limits abroad, wind speed, boat speed or running pace — with every unit listed at once.
- Data Storage Converter Convert file and disk sizes between bytes, KB, MB, GB, TB and KiB, MiB, GiB, and turn Mbit network speeds into MB — so a “shrunken” drive or a slow download makes sense.
- Pressure Converter Convert pressure between psi, bar, kPa, MPa, atm and mmHg — tire pressure, gas cylinders, barometric pressure in weather reports and blood pressure readings.
- Energy Converter Convert energy between kcal, kJ, joules, kWh and BTU — turn the kilojoules on a nutrition label into Calories, or see how much energy a kilowatt-hour of electricity holds.
- Shoe Size Converter Buying shoes from another country and unsure what UK 7 or EU 41 means for you?
- Ring Size Converter The listing says US 7 or UK N — what's your size?
- Cups to Grams Converter The recipe says "1 cup flour, 2 tbsp butter" and you only have a scale?
- Dog and Cat Age Calculator "One dog year equals seven human years" isn't right — a one-year-old dog is already a teenager in human terms, and large dogs age faster than small ones.
- Concrete Calculator Pouring a patio, shed base, footing or post holes?
- Paint Calculator How much paint do you need for a bedroom or living room?
- Tile Calculator Tiling a bathroom or kitchen floor?