Calculators
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Age Calculator
Free age calculator: enter your birth date to see your exact age in years, months, days, hours and minutes, plus the countdown to your next birthday.
Business Days Calculator
Free business days calculator: count the working days between two dates, weekends excluded - useful for deadlines, delivery dates and project planning.
Add Days to Date
Start from any date and move forwards or backwards by days, weeks, months or years - with a business-day mode that skips weekends.
Date Difference Calculator
Free date difference calculator: find the exact time between two dates in years, months, days and weeks, and see how many working days fall in between.
Day of the Week Calculator
Free day of the week calculator: find out which weekday any date falls on - past or future - handy for birthdays, events and historical dates.
Hours Worked
Add start and end times for each day, subtract breaks, and get the week in hours and minutes, in decimal, and in money. Night shifts too.
Leap Year Checker
Free leap year checker: see whether any year has 366 days, why the rule works the way it does, and which leap years come next.
Pregnancy Calculator
Free pregnancy calculator: work out your due date, current week and trimester from your last menstrual period, with the estimated conception date.
Time Difference Calculator
Free time zone calculator: check the current time difference between any two cities worldwide, with daylight saving time already taken into account.
Week Number Calculator
Free ISO 8601 week number calculator: find which week of the year any date falls in, and see the first and last day of that week at a glance.
Home Affordability
Work backwards from your income to a price. Enter what you earn, what you owe and what you have saved, and see the house that fits.
Break-Even Calculator
Free break-even calculator: find how many units you must sell to cover costs, with break-even revenue, contribution margin and profit at any volume.
Card Payoff
See how long a card balance takes to clear and what the interest costs. Pay a fixed amount, or the minimum, and watch the difference.
Compound Interest Calculator
Free compound interest calculator: see the final balance, total interest earned and year-by-year growth for any compounding frequency and regular deposits.
Discount Calculator
Free discount calculator: enter the original price and discount to see the sale price, how much you save and the effective percentage off.
Electricity Cost
Enter watts, hours a day and your tariff to see what an appliance costs per day, month and year. Standby hours are counted separately, because they add up.
Fuel Cost
Work out what a drive costs in fuel, in L/100km, km/L or mpg, and split it between passengers. Handles round trips and both US and UK gallons.
Inflation Calculator
Enter an amount, a rate and a number of years to see two things at once: what the same thing will cost, and what that money will be worth.
Margin Calculator
Enter any two of cost, price, margin and markup — the other two appear. Margin and markup are shown side by side, because they are not the same number.
Percentage Calculator
Work out a percentage of a number, what share one number is of another, the change between two values, and adding or removing a percentage.
ROI Calculator
Free ROI calculator: enter the amount invested and returned to see your ROI percentage, net profit, annualised return and payback period.
Salary Raise Calculator
Free salary raise calculator: enter your current pay and the raise percentage to see your new salary, the increase amount and the yearly difference.
Salary Calculator
Turn any pay figure into all the others: hourly, daily, weekly, fortnightly, monthly and annual. Set your own hours and working weeks.
Savings Goal
Set a target and ask it either way: how much to put aside each month to get there by a date, or how many months a chosen amount will take. Interest included.
Tip Calculator
Work out the tip, the total and what each person owes. Rounding up adjusts the tip rather than the total, which is what actually happens at the table.
VAT Calculator
Work out the tax on a price at any rate, in either direction: add VAT to a net figure or pull it back out of a gross one.
Loan Calculators
Loan Calculator
Free loan calculator for monthly payment, total interest and total cost. Works for personal, auto and other fixed-rate loans, with a full amortization table.
Mortgage Calculator
Free mortgage calculator: estimate your monthly payment including principal, interest, property tax, home insurance and PMI, with the full schedule.
Partially Amortized Loan Calculator
Free balloon loan calculator: enter amount, rate, amortisation term and actual term to see the monthly payment, balloon balance and total cost.
BMI Calculator
Free BMI calculator: enter your height and weight to see your body mass index and which WHO category it falls into, in metric or imperial units.
Body Fat Calculator
Free body fat calculator: estimate your body fat percentage with the U.S. Navy tape method and see which fitness category your result falls into.
Calorie Calculator
Free calorie calculator: estimate your daily calorie needs with the Mifflin-St Jeor formula, based on age, weight, height and activity level.
Fitness Goal Timeline Calculator
Free fitness goal calculator: see how many weeks it will take to reach your target weight from your current stats and weekly effort.
Ideal Weight Calculator
Free ideal weight calculator: see your healthy weight range from height, age and gender using the Hamwi, Devine and Robinson formulas side by side.
Macro Calculator
Split a daily calorie target into grams of protein, carbohydrate and fat. Pick a preset or set your own percentages and watch them balance.
Ovulation Calculator
Enter the first day of your last period and your usual cycle length to see the likely fertile window, ovulation day and next period date.
Pace Calculator
Fill in any two of pace, time and distance and the third appears, along with the split times you need to hold on race day.
Sleep Calculator
Say when you must get up, or when you are going to bed, and see the times that land at the end of a sleep cycle rather than the middle.
Target Heart Rate Calculator
Free target heart rate calculator: find your fat-burn, cardio and peak zones from age and resting pulse using the Karvonen formula.
Water Intake Calculator
Free water intake calculator: work out how much you should drink each day from your weight, activity level and climate, in litres or ounces.
Waist-to-Hip Ratio Calculator
Free waist-to-hip ratio calculator: enter your waist and hip measurements to see your ratio and the health risk band defined by WHO guidelines.
Area Calculator
Work out the area and perimeter of eight common shapes. Pick the shape, fill in the measurements it needs, and the answer updates as you type.
Fraction Calculator
Add, subtract, multiply or divide two fractions. The answer is simplified and also shown as a mixed number and a decimal, so you can use the form you need.
GCF and LCM
Find the greatest common factor and lowest common multiple of two or more whole numbers, with the prime factorisation of each one shown alongside.
Matrix Calculator
Enter two matrices up to four by four and get the sum, product, transpose, determinant or inverse, with the size rules checked for you.
Ohm's Law
Enter any two of voltage, current, resistance and power, and the other two are worked out for you. Every pairing is supported, not just volts and amps.
Permutations & Combinations
Count how many ways r items can be chosen from n, with and without order mattering, and with or without repetition allowed.
Quadratic Solver
Enter a, b and c to solve ax² + bx + c = 0. You get the roots, the discriminant that decides how many there are, and the vertex of the parabola.
Ratio Calculator
Reduce a ratio to its simplest whole numbers, or fill in three of the four values and let the fourth one be worked out for you.
Scientific Calculator
A scientific calculator with trigonometry, logarithms, powers, roots and factorials. Type an expression or use the keypad; degrees and radians both supported.
Scientific Notation
Convert between ordinary decimals and scientific notation in either direction, with engineering notation and a significant figures count alongside.
Standard Deviation
Paste a list of numbers and get the standard deviation, variance, mean, median, mode and range at once - both the sample and the population version.
Significant Figures
Count the significant figures in a number, round it to as many as you need, and apply the right rule when two measurements are combined.
Slope Calculator
Give two points and get the slope between them, the equation of the line, the angle it makes, the distance and the midpoint - all at once.
Triangle Calculator
Solve a right triangle from any two sides, or a general triangle from all three. You get the missing side, all three angles, the area and a drawing to scale.
Volume Calculator
Pick a shape, enter its measurements, and get the volume and surface area at once - with the answer in litres alongside.
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Calculators