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Date & Time Calculators

Free Date & Time Calculators

20+ free date and time calculators — age calculator, days between dates, countdown timer, time zone converter, business days, work hours, and more. Accurate results with US federal holidays built in. No sign-up, no ads.

20+ Free Calculators US Federal Holidays Included Updated 2025 No Sign-Up Required
Quick Age Calculator
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Years Old
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Note on Accuracy: Date calculations account for leap years, Daylight Saving Time transitions, and all 11 US federal holidays. Business day results exclude weekends and federal holidays by default. For legal deadlines or contractual dates, always verify with a qualified professional.

The tools millions of Americans use every month to work with dates and time

🔥 Most Popular Leap Year Aware

Age Calculator

Find out exactly how old you are in years, months, and days — or calculate anyone's age from their date of birth. Enter a custom "as of" date to calculate age at any past or future point in time. Correctly handles February 29 leap year birthdays. Shows your next birthday countdown and the day of the week you were born.

Age in years, months & days Next birthday countdown Day of week born Custom "as of" date Leap year birthdays
how old am I calculate age from date of birth age calculator by birthday how many days old am I
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Top Search

Days Between Dates Calculator

Calculate the exact number of days, weeks, months, or years between any two dates. Toggle business days only to exclude weekends and US federal holidays automatically.

Calendar days Business days Weeks & months
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DST Aware 100+ Zones

Time Zone Converter – World Clock & Meeting Planner

Convert times between any two cities or time zones worldwide. Supports all US time zones (ET, CT, MT, PT, AKT, HAT), all major global zones, and automatically adjusts for Daylight Saving Time transitions. Ideal for scheduling meetings across the US or internationally — see multiple cities simultaneously on the world clock view.

US & world time zones DST auto-adjust Meeting planner World clock view UTC offset display
EST to PST converter what time is it in New York time zone difference calculator
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Popular

Countdown Calculator

Count down the days, hours, minutes, and seconds to any future event — Christmas, New Year's, a birthday, vacation, wedding, or deadline. Save multiple countdowns.

Days & hours left Multiple events Holiday presets
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Business US Holidays

Business Days Calculator – Working Days Between Dates

Count the number of business days (working days) between two dates, automatically excluding weekends and all 11 US federal holidays. Or add a specific number of business days to a start date to find the end date. Essential for project timelines, delivery estimates, invoice terms (Net-30), contract deadlines, and payroll processing.

Business days between dates Add business days to date US federal holidays excluded Net-30 / Net-60 due dates Project deadline finder
how many business days between dates add 30 business days calculator working days calculator US
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Timesheet

Work Hours Calculator

Calculate total hours worked from clock-in and clock-out times, with automatic lunch break deduction. Supports multiple shifts per day and weekly totals for timesheets and payroll.

Daily & weekly hours Break deduction Overtime detection
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Popular

Add / Subtract Days From a Date

Add or subtract any number of days, weeks, months, or years from a date. Find what date falls 90 days from now, 6 months after a date, or 2 years before an event. Business days option included.

Add days to date Subtract days Weeks & months
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High Volume Multi-mode

Date Calculator – Duration, Add/Subtract & Difference

The all-in-one date calculator with three modes: find the duration between two dates, add or subtract time from a date, and convert calendar date to day number of the year. Results shown in years, months, weeks, and days. Includes leap year and DST handling for maximum precision.

Duration mode Add/subtract mode Day of year Week number Leap year aware
date duration calculator what date is 30 days from today what day of the year is today
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Planning

Retirement Date Calculator

Find your exact retirement date based on your date of birth and target retirement age (62, 65, 67, or custom). Shows countdown in years, months, and days, and calculates Social Security full retirement age.

SS full retirement age Early retirement Custom age
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US Time Zones — Quick Reference

Current UTC offsets for all six US time zones (Standard / Daylight Saving)

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Eastern Central Mountain Pacific Alaska Hawaii
Eastern (ET)
UTC−5 / UTC−4 DST
Central (CT)
UTC−6 / UTC−5 DST
Mountain (MT)
UTC−7 / UTC−6 DST
Pacific (PT)
UTC−8 / UTC−7 DST
Alaska (AKT)
UTC−9 / UTC−8 DST
Hawaii (HAT)
UTC−10 (no DST)

DST begins 2nd Sunday in March · Ends 1st Sunday in November · Arizona & Hawaii do not observe DST

20+
Date & Time Tools
11
US Federal Holidays
2025
Data Updated
Free
No Sign-Up Ever

All Date & Time Calculators

Browse the complete list of free date and time tools

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Age Calculator
Exact age in years, months & days from date of birth
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Date Calculator
Duration between dates, add/subtract time, day of year
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Days Between Dates
Calendar days, weeks, months or business days between two dates
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Time Zone Converter
Convert times between US & world zones, DST auto-adjust
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Countdown Calculator
Days/hours until Christmas, New Year's, birthday, vacation
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Time Calculator
Add and subtract hours, minutes & seconds
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Business Days Calculator
Working days between dates, US federal holidays excluded
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Work Hours Calculator
Hours worked per day/week with break deduction
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Add Days to Date Calculator
Add or subtract days, weeks, months, years from any date
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Retirement Date Calculator
Retirement date by age, Social Security full retirement age
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Day of Week Calculator
What day of the week was any date in history?
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Unix Timestamp Converter
Convert epoch/Unix time to human-readable date and back
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Weeks Between Dates
Exact weeks (and partial weeks) between two dates
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Months Between Dates
Full months and remaining days between start and end date
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Time Duration Calculator
Elapsed time between two clock times (hours:min:sec)
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Birthday Countdown Calculator
Days until next birthday, zodiac sign, birthstone
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Leap Year Calculator
Is a year a leap year? Next/previous leap year finder
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Week Number Calculator
ISO week number for any date, dates in a given week
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Quarter Calculator
What fiscal or calendar quarter is a date in?
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Date of Birth Finder
Calculate birth date from a known current age
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Date & Time Reference Tables

Quick reference for US federal holidays, time zones, and calendar facts

Holiday2025 DateDayObserved
New Year's DayJanuary 1WednesdayJan 1
Martin Luther King Jr. DayJanuary 20MondayJan 20
Presidents' Day (Washington's Birthday)February 17MondayFeb 17
Memorial DayMay 26MondayMay 26
Juneteenth National Independence DayJune 19ThursdayJun 19
Independence DayJuly 4FridayJul 4
Labor DaySeptember 1MondaySep 1
Columbus DayOctober 13MondayOct 13
Veterans DayNovember 11TuesdayNov 11
Thanksgiving DayNovember 27ThursdayNov 27
Christmas DayDecember 25ThursdayDec 25

Source: US Office of Personnel Management (OPM). When a holiday falls on a Saturday, it is observed the preceding Friday; if on Sunday, the following Monday.

Time ZoneAbbreviationUTC Offset (Standard)UTC Offset (DST)Example Cities
Eastern TimeETUTC−5UTC−4New York, Miami, Atlanta
Central TimeCTUTC−6UTC−5Chicago, Dallas, Houston
Mountain TimeMTUTC−7UTC−6Denver, Phoenix*, Salt Lake City
Pacific TimePTUTC−8UTC−7Los Angeles, Seattle, San Francisco
Alaska TimeAKTUTC−9UTC−8Anchorage, Fairbanks
Hawaii TimeHATUTC−10No DSTHonolulu, Hilo
Greenwich Mean TimeGMT/UTCUTC+0UTC+1 (BST)London, Dublin, Lisbon
Central European TimeCETUTC+1UTC+2 (CEST)Paris, Berlin, Rome
India Standard TimeISTUTC+5:30No DSTMumbai, Delhi, Bangalore
China Standard TimeCSTUTC+8No DSTBeijing, Shanghai, Hong Kong
Japan Standard TimeJSTUTC+9No DSTTokyo, Osaka
Australian Eastern TimeAESTUTC+10UTC+11 (AEDT)Sydney, Melbourne

*Phoenix, Arizona observes Mountain Standard Time year-round and does not observe DST.

FactValueNotes
Days in a common year365 daysNon-leap year
Days in a leap year366 daysExtra day: Feb 29
Leap year ruleDivisible by 4Except centuries not divisible by 400
Weeks in a year52 weeks + 1 day52 weeks + 2 days in leap years
Business days in a year (approx.)~250 daysAfter weekends and 11 US federal holidays
Days in each quarter90–92 daysQ1: 90/91 · Q2: 91 · Q3: 92 · Q4: 92
Unix Epoch (start)Jan 1, 1970 UTCTimestamp = 0
Gregorian calendar startOctober 15, 1582Replaced Julian calendar
US fiscal year startOctober 1Federal government fiscal year
ISO week starts onMondayISO 8601 standard
YearSpring Forward (Begins)Fall Back (Ends)DST Duration
2025March 9 (2:00 AM)November 2 (2:00 AM)238 days
2026March 8 (2:00 AM)November 1 (2:00 AM)238 days
2027March 14 (2:00 AM)November 7 (2:00 AM)238 days
2028March 12 (2:00 AM)November 5 (2:00 AM)238 days

DST is observed across the contiguous US, Alaska, and most US territories. Arizona (except Navajo Nation), Hawaii, Puerto Rico, US Virgin Islands, American Samoa, and Guam do not observe DST.

Date & Time Calculators — What People Search For

From "how many days until Christmas" to "what day is 90 days from now" — these are the most common date and time questions Americans search for every month. Our calculators answer them all instantly.

Age & Birthday

How old am I in years, months, days Calculate age from date of birth How many days until my birthday How old would I be if born in [year] How many days old am I Age calculator by birthday

Date Differences & Duration

How many days between two dates What date is 30 / 60 / 90 days from today How many business days between dates How many weeks between two dates Add 90 days to a date How many days until Christmas 2025

Time Zones & Work

What time is it in New York / LA / Chicago Convert EST to PST / CST / MST How many hours did I work today Best meeting time across US time zones Weekly hours calculator for timesheet Current Unix timestamp

Date & Time Calculator FAQs

Answers to the most common date and time questions from Americans

How do I calculate the number of days between two dates?
Enter your start and end date in our Days Between Dates Calculator and it returns the exact count in calendar days, weeks, months, and years. Toggle Business Days Only to automatically exclude weekends and all 11 US federal holidays — useful for calculating project timelines, shipping estimates, or contract deadlines.
How is age calculated from a date of birth?
Age is the difference between your date of birth and today's date. Our Age Calculator shows your exact age in years, months, and days, accounts for leap year birthdays (Feb 29), displays the day of the week you were born, and counts down to your next birthday. You can also set a custom "as of" date to calculate age at any point in time.
What is the difference between calendar days and business days?
Calendar days count every day of the week including weekends. Business days (working days) count only Monday–Friday, excluding weekends and public holidays. Our Business Days Calculator automatically excludes all 11 US federal holidays. Commonly used for Net-30 payment terms, shipping estimates, legal notices, and project deadlines.
How do US time zones work?
The contiguous US has four main zones: Eastern (ET), Central (CT), Mountain (MT), and Pacific (PT). Alaska uses AKT and Hawaii uses HAT. During DST (2nd Sunday in March through 1st Sunday in November), clocks shift one hour forward. Arizona and Hawaii do not observe DST. Use our Time Zone Converter to convert times between any zones automatically.
How many business days are in a year in the US?
A typical US year has approximately 250 business days — calculated from 365 calendar days, minus 104 weekend days, minus 11 federal holidays (some of which may fall on weekends). Leap years add one day, which may or may not be a weekday. Use our Business Days Calculator for any specific date range.
What is a Unix timestamp and how do I convert it?
A Unix timestamp (also called Epoch time) is the number of seconds since January 1, 1970, 00:00:00 UTC. It's the universal standard in programming and databases. Our Unix Timestamp Converter instantly converts any timestamp to a human-readable date, or converts any date to its Unix timestamp. The current Unix timestamp updates every second.
How do I add or subtract days from a date?
Use our Add Days to Date Calculator. Enter a starting date and the number of days to add (positive number) or subtract (negative number). It correctly handles month-end rollovers, year crossings, and leap years. You can also add only business days to skip weekends and US federal holidays — helpful for calculating Net-30 or Net-60 due dates.
When does Daylight Saving Time start and end in the US?
US Daylight Saving Time (DST) begins on the 2nd Sunday of March at 2:00 AM (clocks spring forward 1 hour) and ends on the 1st Sunday of November at 2:00 AM (clocks fall back 1 hour). In 2025: begins March 9 and ends November 2. Arizona (except Navajo Nation) and Hawaii do not observe DST. Our Time Zone Converter auto-adjusts for DST.

How We Build Our Date & Time Calculators

Every date and time calculator on this site is built on the ISO 8601 international date standard, the Gregorian calendar (in use since October 15, 1582), and the US federal holiday schedule published annually by the Office of Personnel Management (OPM). All calculations account for leap years using the standard rule: divisible by 4, except century years not divisible by 400.

Our Time Zone Converter uses the IANA Time Zone Database (the same standard used by operating systems, browsers, and programming languages worldwide) for accurate DST transition handling. Our Age Calculator follows the conventional Western age counting method, which counts each elapsed year from the birthday date — including correct handling of February 29 leap year birthdays.

Business day calculations use the 11 federally designated US public holidays as defined under 5 U.S.C. § 6103. When a holiday falls on a Saturday, the preceding Friday is observed; when it falls on a Sunday, the following Monday is observed — matching the official US federal government observance calendar.

The Unix Timestamp Converter uses POSIX time (seconds since January 1, 1970, 00:00:00 UTC), the standard implemented by virtually every modern operating system and database. All time conversions are performed in UTC internally and converted to local time zones using IANA data to avoid DST edge-case errors.