Calc tools

Everyday calculators — percentages, unit conversion, data sizes — that compute in your browser with no tracking. Each is careful about the detail people get wrong: percent change is measured against the starting value (so a rise and the matching fall are different percentages), temperature conversion uses proper formulas rather than a bare ratio, and data sizes are shown in both decimal and binary because that is why a "1 TB" drive reports as 931 GB.

• Break-Even CalculatorFind how many units you must sell to cover your costs.
• Data Size ConverterConvert between bytes, KB, MB, GB and TB — decimal and binary, side by side.
• Discount CalculatorWork out a sale price and how much you save.
• Percentage CalculatorThe three percentage questions people actually ask — each with its own formula.
• Profit Margin & Markup CalculatorCalculate profit margin from cost and sale price.
• Random Number GeneratorGenerate random numbers in a range, without modulo bias.
• ROI CalculatorCalculate return on investment as a percentage.
• Time Duration CalculatorWork out the time between two dates or times.
• Unit ConverterConvert length, weight, temperature and volume between common units.
• VAT / Sales Tax CalculatorAdd or remove VAT (sales tax) from a price.