Time and Date Calculators
Calculate an age, find a deadline, convert a timestamp, or compare times around the world. Choose your task and get a result directly in your browser.
What would you like to calculate?
Date math calculators
- Date Calculator
Add or subtract days and compare two dates.
- Age Calculator
Calculate exact age in years, months, and days.
- Countdown
Track how much time remains until a target date.
- Working Days
Count business days between dates.
- Stopwatch
A precise online stopwatch with lap and split timing.
Converters and technical tools
- Timezone Converter
Convert a date and time between world time zones.
- Julian Date Converter
Convert calendar dates into Julian day references.
- Unix Timestamp
Convert epoch time and inspect common timestamp formats.
Quick counters and references
- Seconds Since 1970
A focused live epoch-second counter.
- Today's Date and Time
Current local date and time with ISO, UTC, and ordinal formats.
- Current Time
A live local clock with 12-hour, 24-hour, and fullscreen views.
Choose the calculator that matches the question
“How old am I?” needs completed years and months, so use the age calculator. “How many days are between these dates?” needs a date difference. “How long until the event starts?” needs an exact target time, so use the countdown. The inputs look similar, but each result measures something different.
Know what your result includes
Calendar differences count date boundaries. Working days exclude Saturdays and Sundays and can optionally exclude observed US federal holidays. Stopwatch laps measure elapsed intervals in the current browser session. The timezone converter needs the event date because an offset today may differ from the offset on the day you are planning.
Keep a result you can explain
When sharing a calculation, include the original dates, the chosen units, and any holiday or time-zone settings. “Five working days, excluding the starting Monday and weekends” is much more useful than “five days.” The examples and methodology notes on each tool explain these assumptions.
Explore the reference guides
Understand the rules behind a result, with examples and comparisons.