Free online calculators and tools
Simple tools that do one thing well. Nothing to install, nothing to sign up for.
Dates
Age Calculator
Find your exact age in years, months and days, and how long until your next birthday.
Date Difference
Count the days, weeks and months between any two dates.
Days Until
How many days are left until a holiday, a deadline or any future date.
Business Days
Count business days between dates, or find when a deadline in working days lands.
Time Zone Converter
What time is it there, and what time will your meeting be for them.
Week Number
Which week of the year a date falls in, and the week it belongs to.
Day of the Year
The sequential day number, how many remain, and how much of the year has passed.
Countdown Timer
A live countdown to any date: days, hours, minutes and seconds, ticking.
Time Calculator
Add hours and minutes, or find the time between two clock times.
Hours Between Two Times
How long from clock-in to clock-out, with the break taken off (night shifts included).
Add and Subtract Time
Add up durations in hours and minutes: the sum an ordinary calculator gets wrong.
What Time Will It Be
The time a set number of hours or minutes from now, past midnight if it goes there.
Astronomy
Moon Phases
Today’s phase and the exact times of every new and full moon, in your time zone.
Sunrise & Sunset
Sunrise, sunset, twilight and day length for your location or any major city.
Equinox and Solstice
When each season starts, to the minute, and why the date moves.
Lunar Eclipse
Every lunar eclipse to come, with the exact time in your own time zone.
Health
BMI Calculator
Body mass index from your height and weight, with the range it falls in.
Calorie Calculator
Estimated daily energy use from the Mifflin-St Jeor equation, with its margin.
Ovulation Calculator
Estimated fertile window and ovulation day from your cycle length.
Due Date Calculator
Estimated due date, gestational age and trimester, adjusted for your cycle.
Finance
Numbers
Fraction Calculator
Add, subtract, multiply and divide fractions: exactly, never rounded.
Proportion Calculator
Solve a proportion, including the inverse case the usual formula gets wrong.
Random Number Generator
Draw numbers in any range, with or without repeats, and without the bias most generators have.
Random Name Picker
Paste a list and draw a winner, or shuffle the whole list into a fair order.
Coin Flip
Flip once to decide, or a hundred times to watch the halves even out.
Dice Roller
Roll any dice, from d4 to d100, plus the total for when the game needs it.
Random Number 1 to 100
The most asked range, already filled in: draw one number or a hundred.
Percentage Calculator
What is X% of Y: the everyday percentage, worked out step by step.
Percentage Increase
Add a percentage to a value, or find the increase between two numbers.
Discount Calculator
The price after a discount, and the price before it, from the sale tag.
Tip Calculator
The tip, the total and what each person owes (including the cent that does not divide).
Percentage Difference
How far apart two values are, with neither one as the reference.
Percentage of a Total
X is what percent of Y: the share one number is of another.
Converters
Ethanol or Gasoline
Which fuel pays off at today’s prices, for your car.
Length Converter
Centimeters to inches, meters to feet, kilometers to miles.
Weight Converter
Kilograms to pounds, grams to ounces, and back again.
Temperature Converter
Celsius to Fahrenheit and Kelvin, with the offset done right.
Area Converter
Square meters, square feet, hectares and acres.
Volume Converter
Liters to gallons, milliliters to fluid ounces.