Date and Time Calculators

A growing set of free, accurate calculators for working with dates and time. Every tool runs instantly in your browser with no sign up.

Date Calculators

Find dates, measure the time between dates, and move forward or backward across the calendar.

Date Calculator Add or subtract days, weeks, months, and years from any date. Option to skip weekends and holidays. Free, accurate, and instant date calculator.
Date Difference Calculator Find the exact time between two dates in years, months, weeks, and days. Includes a business days option and inclusive counting. Free and instant.
Day of Year Calculator Find what day number of the year any date is, from 1 to 365 or 366, plus how many days remain in the year. Convert a day number back to a date too.
Week of Year Calculator Find the ISO and US week number for any date, see the start and end of that week, and learn how week numbering works. Free and accurate week calculator.
Quarter Calculator Find which calendar quarter any date falls in, with the exact start and end dates and days remaining in the quarter. Free, fast, and accurate.

Duration Calculators

Measure elapsed time between two points, count working days, and plan around business calendars.

Time Duration Calculator Calculate the hours and minutes between two times of day, with AM and PM support and overnight handling. Free time duration calculator for work and shifts.
Working Days Calculator Count the working days between two dates, excluding weekends and your own custom holidays. Free business days between dates calculator.
Business Day Calculator Add or subtract business days from a date, skipping weekends and custom holidays, to find the resulting working day. Free business day calculator.

Time Ago and From Now

Move backward or forward from today, or count down to a future date and time.

Time Ago Calculator Find the exact date and day of the week a set number of days, weeks, months, or years ago. Free time ago calculator with instant results.
Time From Now Calculator Find the exact future date and day of the week a set number of days, weeks, months, or years from now. Free time from now calculator, instant results.
Time Until Calculator Count the days, hours, and minutes until any future date and time with a live countdown. Free time until calculator for events and deadlines.

Timestamp Tools

Convert between Unix timestamps, spreadsheet serial numbers, Discord codes, and human dates.

Unix Timestamp Converter Convert a Unix timestamp or epoch time to a human date, and convert any date back to a timestamp. Seconds and milliseconds, UTC and local time. Free.
Discord Timestamp Generator Generate Discord timestamp codes that show a date in every reader local time zone. Pick a style, copy the code, and paste it into any message. Free.
Excel Date Converter Convert an Excel serial number to a calendar date, and convert any date to its Excel serial number. Handles the spreadsheet date system. Free and instant.

Time Conversion Tools

Convert between time units and switch between 12 hour, 24 hour, and different date formats.

Time Unit Converter Convert between time units including seconds, minutes, hours, days, weeks, months, and years. Free time unit converter with instant, accurate results.
12 and 24 Hour Converter Convert 12 hour AM and PM times to 24 hour military time and back. Free 12 to 24 hour converter with a full conversion chart and instant results.
Date Formatter Convert a date into ISO 8601, RFC style, US, European, and long written formats at once. Free date format converter with copy ready results.

Time Arithmetic

Add, subtract, multiply, divide, and average lengths of time, and work with time percentages.

Add and Subtract Time Add or subtract hours, minutes, and seconds and get the total in HH MM SS. Free time addition and subtraction calculator with instant results.
Multiply and Divide Time Multiply or divide a length of time by a number to scale a duration up or down. Free multiply and divide time calculator with instant HH MM SS results.
Average Time Calculator Find the average of several durations or lap times in hours, minutes, and seconds. Free average time calculator for splits, laps, and sessions.
Time Percentage Calculator Find a percentage of a duration, or what percent one time is of another, including completed and remaining. Free time percentage calculator.

Health and Lifestyle

Plan sleep, study, reading, screen time, and travel around the hours in your day.

Sleep Calculator Find the best times to go to bed or wake up based on 90 minute sleep cycles. Free sleep calculator with bedtime and wake up time suggestions.
Reading Time Calculator Estimate how long a text takes to read from the word count and your reading speed. Free reading time calculator for articles, books, and speeches.
Screen Time Calculator Add up your daily screen time and see the weekly and yearly totals. Free screen time calculator to understand and manage your device use.
Study Time Calculator Plan your study time into focused sessions with breaks and see how long the whole plan takes. Free study time calculator for students and revision.
Travel Time Calculator Work out your arrival time from a departure time and a journey length, or find the duration between departure and arrival. Free travel time calculator.

Free Online Date and Time Calculators

These calculators help you answer everyday questions about dates and time. You can add or subtract time from a date, measure the gap between two dates, find the day number or week number of any date, and see which quarter a date falls in.

Every tool is free to use, works on phones and computers, and gives an instant answer the moment you change an input. More calculators for durations, timestamps, and planning are on the way.