Everyday calculators
The small calculations that come up all the time: how many days until a date, exact age for a form, hours on a timesheet, whether a tire or wheel will fit, what size to order. Each one gives the answer first and the reasoning underneath, so you can check it or explain it to someone else.
Most used
- Age calculator
Calculate your exact age from your date of birth, or the age on any date. See age in months, weeks, days and hours, the weekday you were born, and your next birthday.
- Date calculator
Count the days, weeks, months and business days between two dates, or add and subtract days, weeks, months or business days from a date to find the result and its weekday.
- Tire size calculator
Decode a tire size like 205/55R16 into diameter, sidewall height and circumference, and compare it with another size to see the difference and the speedometer error.
Dates and time
- Age calculator
Calculate your exact age from your date of birth, or the age on any date. See age in months, weeks, days and hours, the weekday you were born, and your next birthday.
- Date calculator
Count the days, weeks, months and business days between two dates, or add and subtract days, weeks, months or business days from a date to find the result and its weekday.
- Hours calculator
Work out how many hours and minutes are between a start and end time, subtract breaks, convert to decimal hours for payroll, and see the pay at your hourly rate.
- Time card calculator
Add up hours for each day of the week, split regular and overtime hours using a weekly (and optional daily) threshold, and calculate gross pay at your rate and overtime multiplier.
Cars
- Tire size calculator
Decode a tire size like 205/55R16 into diameter, sidewall height and circumference, and compare it with another size to see the difference and the speedometer error.
- Wheel offset calculator
Compare your current wheels with a new set by width and offset (ET) to see how far the outer and inner edges move, poke toward the fender, clearance to the suspension, and the effect of spacers.
Sizes
- Bra size calculator
Measure under your bust and around the fullest part to get your bra size, or convert a size you already know between US, UK, EU, French, Australian and Japanese systems, with sister sizes.
- Ring size calculator
Measure the inside diameter of a ring or the circumference of your finger and get your ring size in US, UK, EU and Japanese systems, with nearby sizes and fitting tips.
School
- SAT score calculator
Combine your Reading and Writing and Math section scores into a total SAT score, see the national percentile, compare with college score ranges, and find out how many points you need for a target.
Questions about these calculators
Do the date calculators account for leap years?
Yes. Dates are calculated on the real calendar, so February 29 and month lengths are handled correctly.
Can I share a result?
Every calculator has a Copy link button that produces a link with your inputs; opening it restores the calculation.
Are the size charts the same as in shops?
They follow the published standards (ISO for rings, the common band-and-cup method for bras), but brands vary by up to half a size. Use the result as the starting point and check the brand’s own chart.