Converters & Calculators
Free online unit converters and calculators: length, weight, temperature, percentage.
8 tools
Converters & Calculators covers the everyday number work that usually means hunting for a formula or opening a spreadsheet. Four unit converters handle length, weight, temperature and volume between the metric and imperial systems. The rest are single-purpose calculators: percentages in three common forms, the exact span between two calendar dates, and image or video aspect ratios. Each tool recalculates as you type and runs entirely in your browser, so the values you enter are never uploaded or stored.
Which tool should I use?
- Use the Length, Weight, Temperature or Volume Converter when you have a value in one unit and need it in another — grams to ounces, miles to kilometres, Celsius to Fahrenheit.
- Use the Percentage Calculator for a discount, a tip, what share one number is of another, or the percentage change between two values.
- Use the Date Difference Calculator for the exact number of days between two dates, plus a years-months-days breakdown.
- Use the Aspect Ratio Calculator to reduce a width and height to a ratio like 16:9, or to scale one side while keeping the proportions.
Limitations and things to know
- Converted values are shown rounded to four decimal places (percentages to two), so they are display approximations, not full-precision results.
- Gallons and cups use United States definitions; the converters do not include imperial (UK) volumes, stones, nautical miles or metric tonnes.
- The Date Difference Calculator compares calendar dates only — no business days, public holidays, working hours or time zones.
- Percentage change has no defined result when the starting value is zero.
Unix Timestamp Converter
Convert between Unix timestamps and readable date-time values for quick debugging and data checks.
Use toolDate Difference Calculator
Get the exact number of days between two calendar dates, plus a years, months and days breakdown.
Use toolAspect Ratio Calculator
Simplify a width and height to a ratio like 16:9, or scale one side while keeping the proportions.
Use toolPercentage Calculator
Work out X% of Y, what percentage X is of Y, and the percentage change between two values.
Use toolVolume Converter
Convert between litres, millilitres, US gallons and US cups, updated as you type.
Use toolTemperature Converter
Convert between Celsius, Fahrenheit and Kelvin using exact formulas, not a single multiplier.
Use toolWeight Converter
Convert between kilograms, grams, pounds and ounces, with the result updating live.
Use toolLength Converter
Convert between metres, kilometres, centimetres, millimetres, miles, yards, feet and inches, updated as you type.
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