Calculators
Age Calculator
Enter two dates — a start date and an end date — to calculate the exact difference in years, months, days, weeks and total days.
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Free Calculators
Accurate everyday calculators for age, percentages, BMI, calories and more — fast, private and free.
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Calculators
Percentage Calculator
Free percentage calculator for what is X% of Y, X is what percent of Y, percentage increase and percentage decrease.
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Calculators
BMI Calculator
Calculate BMI from height in centimetres and weight in kilograms, or switch to feet, inches and pounds. Includes WHO adult category and healthy weight range.
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Calculators
Calorie Calculator
Estimate maintenance calories (TDEE) from BMR and activity, then optional calorie deficit or surplus targets for weight change.
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Calculators
Discount Calculator
Calculate a percent off an original price, or the discount between an original price and a sale price, including what you save.
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Date & Time Tools
Pregnancy Due Date Calculator
Estimate a due date, conception date and gestational age from LMP, a known due date or conception using Naegele’s 280-day rule.
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Calculators
Average Calculator
Calculate mean, and related averages from a list of numbers.
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Calculators
Fraction Calculator
Add, subtract, multiply and divide fractions with simplified results.
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Calculators
Ratio Calculator
Simplify ratios and scale quantities proportionally.
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Related guides
- How to Calculate a Pregnancy Due DateNaegele’s rule is a 40-week calendar from LMP. Ultrasound and cycle length can move the date. This page will not replace a clinician.
- How to Calculate Daily CaloriesMaintenance calories are BMR times activity. A 500 kcal gap is a common planning figure — not a guarantee of 0.5 kg a week.
- How to Calculate Discount and Sale Price“20% off” means you pay 80%. Reconstructing the original from a sale tag is a different formula.
- How to Calculate PercentagePercent means “per hundred”. Most day-to-day questions collapse into three formulas — and one division-by-zero trap.
- How to Calculate AgeAge is a calendar difference, not “days ÷ 365”. Here is the method this site uses, including leap days.
- How to Calculate BMIBody mass index is a height-and-weight ratio, not a diagnosis. Here is the formula this calculator uses.