Duration Calculator

  • Weeks Between Dates Calculator
    Calculate the exact number of weeks and days between two dates. Enter a start and end date to get total weeks, remainder days, and decimal weeks.
  • Sleep Cycle Calculator
    Free sleep cycle calculator. Find the best bedtime or wake-up time based on 90-minute sleep cycles plus the time it takes you to fall asleep.
  • Rule of 72 Doubling Time Calculator
    Use the Rule of 72 to estimate how many years it takes an investment to double at a given annual rate. Fast, free doubling time calculator.
  • Video Playback Speed Time Calculator
    Find out how long a video takes to watch at 1.25x, 1.5x, 2x or any speed. Enter the length and speed to see your watch time and time saved.
  • Years to Days Calculator
    Convert years to days instantly. Enter any number of years and get the equivalent days using the 365.25-day average year (accounts for leap years).
  • Add Months to a Date Calculator
    Add (or subtract) any number of months to a date. Handles month-end overflow by clamping the day to the last valid day of the resulting month.
  • Subtract Days From a Date Calculator
    Subtract any number of days from a date instantly. Enter a start date and the days to subtract to get the exact earlier calendar date.
  • Days Lived Calculator
    Find out exactly how many days you have lived. Enter your date of birth and an end date to count the total days, weeks, hours and years between them.
  • Shift Length Calculator
    Calculate how many hours you worked in a shift from start and end times minus your unpaid break. Handles overnight shifts that cross midnight.
  • Relationship Length Calculator
    Find out exactly how long you've been together. Enter your relationship start date to get years, months, days, total weeks and total days.
  • Calendar Days vs Business Days Calculator
    Count business days (workdays) between two dates. Subtracts weekends and optional public holidays from total calendar days. Free workday calculator.
  • 30 Days From Today Calculator
    Find out what date is 30 days from today (or any number of days). Get the exact future date and weekday instantly with this free date calculator.
  • Ovulation Date Calculator
    Estimate your ovulation day and fertile window from the first day of your last period and your average cycle length. Free, fast, and easy to use.
  • Years to Months Calculator
    Convert years into months instantly. Enter any number of years and this free calculator returns the equivalent number of months (years × 12).
  • Months From Today Calculator
    Find the exact date a set number of months from today (or before today). Add or subtract calendar months with automatic month-end day clamping.
  • Months to Days Calculator
    Convert months to days instantly. Uses the average month length of 30.4375 days for accurate, year-aware results. Free online months-to-days calculator.
  • Hours, Minutes & Seconds Addition and Subtraction Calculator
    Add and subtract up to five time durations in hours, minutes and seconds, with a repeat multiplier. Get a normalized H:M:S total plus decimal hours, minutes and seconds.
  • Road Trip Time Calculator
    Estimate total road trip time from distance, average speed, and rest stops. Adds driving time plus break time for a realistic arrival estimate.
  • Year Progress Calculator
    Find out what percentage of the year has passed for any date. Calculates day of year, days remaining, and year progress percent for leap and non-leap years.
  • How Many Weeks Pregnant Am I?
    Find out how many weeks and days pregnant you are from your last menstrual period (LMP). Enter your LMP and an as-of date to get gestational age instantly.
  • Weeks From Today Calculator
    Find the exact date N weeks from today (or before today). Enter a number of weeks to get the target date, weekday, and total day offset instantly.
  • Milliseconds to Seconds Calculator
    Convert milliseconds to seconds instantly. Enter any value in ms and get the equivalent seconds using seconds = milliseconds ÷ 1000.
  • Layover / Connection Time Calculator
    Calculate your flight layover or connection time in minutes between arrival and next departure, and check if it beats the minimum connection time.
  • Pregnancy Weeks to Months Calculator
    Convert weeks pregnant to months instantly. Enter your gestational age in weeks to see how many months pregnant you are, using 4.34524 weeks per month.

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