Time & Date
Plan around calendars, time zones, and deadlines — without guessing the math.
From counting down to a trip to reconciling business-day deadlines across offices, time questions hide tricky edge cases: leap years, month lengths, weekends, zones, and daylight saving. Our tools spell out what they count (calendar days vs business days, inclusive vs exclusive ranges, UTC vs local) so you can trust the answer for scheduling, HR rules, school dates, and everyday planning.
Days & ranges
Compare two dates, add or subtract spans, and see how many calendar days sit between events—including month and leap-year effects.
Workweek counts
Skip weekends (and optionally holidays) when you care about banker days, SLA windows, or office schedules—not just raw 24-hour spans.
Zones & UTC
Translate between regions and offsets so meetings and timestamps line up when the clock “moves” with DST or geography.
Unix & timestamps
Epoch seconds underpin APIs and logs; converting to human dates keeps debugging and data checks grounded.
Calculators
View all time & date toolsCalendar
Browse months and years—useful for planning around weekends, holidays, and fiscal or academic calendars.
Age Calculator
Age in years (and often months/days) from a birthday, with leap-day and boundary-date awareness.
Countdown Timer
Live countdown to a date and time—great for events, launches, and deadlines with clear remaining units.
Date Add/Subtract
Shift a start date by days, weeks, or months for contracts, renewals, and “90 days from…” style rules.
Days Between Dates
Count days from one date to another; tools usually clarify inclusive vs exclusive counting in the UI.
Days Until
Days remaining to holidays or custom dates—often paired with holiday and seasonal coverage on the site.
Days From Today
What calendar date falls N days from today—forward planning without mental date arithmetic.
Days Before Today
The date that was N days ago—handy for lookbacks and reporting windows.
Business Days From Today
The business date N working days from today, excluding weekends (and holidays where configured).
Business Days Before Today
The business date N working days before today for SLA-style “go-back” windows.
Time Left Visualizer
See time remaining split into days, hours, minutes—visual context around a target instant.
Roman Numeral Converter
Convert between Arabic numerals and Roman notation for outlines, copyright years, and puzzles.
Time Zone Converter
Translate an instant between regions and offsets so collaboration across zones stays accurate.
Unix Timestamp Converter
Convert Unix epoch seconds (or milliseconds) to readable dates and back—common for developers and log review.
Guides & Articles
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Formula Quick Reference
How these tools think about dates and clocks—definitions vary slightly by calculator, so check each page for inclusive ranges and holiday rules.
| Formula | Equation | Variables | Result unit | Calculator |
|---|---|---|---|---|
| Calendar days between | count of midnights spanned | depends on inclusive/exclusive choice in the tool | days | Use calculator → |
| Age (years) | complete birthday anniversaries passed | birth date vs “as of” date | years (+ optional months/days) | Use calculator → |
| Date add/subtract (days) | start ± N calendar days | N can span months; leap days affect Februaries | calendar date | Use calculator → |
| Business days | skip Sat/Sun (± holidays) | definition matches your tool’s holiday rules | business days or resulting date | Use calculator → |
| Unix epoch | t = 1970-01-01 00:00:00 UTC + seconds | use UTC for canonical interpretation | s (or ms) | Use calculator → |
| UTC offset | local = UTC + offset | offset includes DST when applicable | hours / zone | Use calculator → |
| Roman numerals | additive + subtractive (IV, IX, …) | symbols I V X L C D M | Roman / Arabic | Use calculator → |
| Countdown duration | Δ = target instant − now | split into days, hours, minutes, seconds | mixed units | Use calculator → |
Watch & Learn
Quick explainers on calendar rules and how computers keep time—helpful context before using date math and timestamp tools.
Why Do We Have Leap Years?
How the calendar stays aligned with Earth’s orbit—context for leap days and date-difference tools.
Leap Years Don't Happen Every 4 Years
The full Gregorian leap rules—why “every four years” is an oversimplification when counting far-apart dates.
Network Time Protocol (NTP)
How computers agree on the time—related background for Unix timestamps, logs, and synchronized clocks.
Frequently Asked Questions
Calendar quirks, business-day rules, and timestamps—answered in plain language.