Calculators
Browse 14 free browser tools for calculation tasks, available directly in your browser.
14 tools
About these tools
A calculator that returns a number and nothing else is hard to trust and impossible to check. These show the working: the formula used, the assumptions it rests on, and where the answer stops being reliable.
The percentage tools cover the arithmetic people most often get backwards — reversing an increase is a division, not a subtraction, and a 50% fall needs a 100% rise to undo it. The business ones separate margin from markup, which are calculated from the same two numbers and answer different questions.
The health and body estimators use published equations and say which one they are using. They describe populations rather than individuals, so they are a starting point for a conversation with someone qualified, not a substitute for one. None of them is medical advice and none of them stores what you enter.
Percentages and business
The arithmetic behind pricing and reporting.
- Percentage IncreaseFind the percentage increase between two numbers, add a percentage to a value, or undo a rise…Calculators
- Percentage DecreaseTake a percentage off a price, or measure how far a figure has dropped.Calculators
- Percentage ChangeFind the change between two numbers as a percentage, in either direction…Calculators
- Margin CalculatorWork out gross margin and markup from cost and revenue, and solve in either direction.Calculators
- Break-even CalculatorFind how many units you must sell to cover fixed and variable costs…Calculators
- Compound Growth CalculatorProject a starting amount plus optional regular contributions compounding yearly, monthly…Calculators
Body and fitness
Estimates from published formulas, with their limits stated.
- BMR CalculatorEstimate basal metabolic rate from height, weight, age and sex using published equations…Calculators
- Macro CalculatorTurn a daily calorie target into gram targets for protein, carbohydrate and fat at the ratio you…Calculators
- Water Intake CalculatorEstimate a daily fluid target from body weight and activity.Calculators
- Pace CalculatorWork out running pace per kilometre or mile, the time a distance will take at that pace…Calculators
- Ovulation CalculatorEstimate the likely fertile window from your cycle length and last period date.Calculators
- Pregnancy Due Date CalculatorEstimate a due date from a last menstrual period or a conception date…Calculators
Dates and time
Working days, and the same moment in two places.
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