Editorial & EEAT Integrity

Our articles, comparison tables, and equations are authored entirely by senior technical communicators and professional mathematicians. We verify formulas against NIST, BIPM, and ISO guidelines before publishing to ensure absolute factual integrity.

Time & Duration Calculator Suite

Fast, accurate tools for anything involving time — elapsed hours, date math, work shifts, and time zones. Pick a calculator below and get your answer in seconds.

Time Calculators

Time Duration Calculator — Find out exactly how many hours, minutes, and seconds sit between two clock times. Works with AM/PM or 24-hour time.
Time Addition & Subtraction Calculator — Sum or subtract cumulative lists of hours, minutes, and seconds with sexagesimal carryovers.
Time Difference Calculator — Compare two times or timestamps and get the gap down to the minute.
Working Hours Calculator — Total up paid hours for a shift, including unpaid breaks — useful for timesheets and payroll.
Overnight Shift Calculator — Built specifically for shifts that cross midnight, where a normal calculator gets the math wrong.
FLSA 7-Minute Rule Calculator — DOL 29 CFR § 785.48(b) compliant 15-minute time clock rounding calculator.
Countdown Timer — Set a countdown to any date and time, live-updating.
Stopwatch / Timer — Simple, ad-light stopwatch and countdown timer tools you can run right in the browser.

Date Calculators

Date Duration Calculator — Get the full gap between two dates in years, months, weeks, and days — useful for contracts, anniversaries, or project timelines.
Date Add/Subtract Calculator — Add or subtract days, weeks, months, or years from any date. Handy for deadlines, due dates, and expiry calculations.
Age Calculator — Enter a birth date and get an exact age in years, months, and days (down to the hour, if you want it).
Business Days Calculator — Count working days between two dates, automatically skipping weekends and holidays.
Leap Year Calculator — Check whether any given year is a leap year, and see the next one coming up.

Time Zone & Format Tools

Country Time Difference — Compare current time and UTC offset between two countries or cities.
Military Time Converter — Convert between 12-hour and 24-hour (military) time instantly.
Time to Decimal Converter — Turn hours:minutes into decimal hours (e.g. 7:30 → 7.5) — built for payroll and billing.
Minutes to Decimal Converter — Convert fractional minutes (1–60) into standard decimal hour equivalents for timesheets.
Unix Timestamp Converter — Convert Unix/epoch timestamps to readable dates, and back.

Guides & How-Tos

Not sure which calculation you need, or want to understand the math behind it? These guides walk through the formulas step by step.

How to Calculate Time Duration Between Two Times
The Complete Guide to Time & Date Calculations
Converting Seconds to Minutes (and Back)
Browse Complete Calculator Suite Directory
See all guides →