Pebbles

Date Calculator

Master Utility

Pebbles

Date Calculator Hub

Start Date

Operation

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A date calculator is a simple tool that helps you calculate dates. You can use this calculator for three main functions: to find the date that comes after a certain number of days, to find out what date was before a certain number of days, and to calculate how many days, weeks, and months between two given dates. This calculator is ideal for planning events, creating deadlines, calculating age, and more.

Definition of dates and format

Date helps us keep track of time. The most common calendar used today is the Gregorian calendar, which started in 1582. This system is the refined version of the older Julian calendar, especially how leap years were counted. This calendar has 12 months and 365 days, or 366 in a leap year.
Date formats vary globally: ISO 8601 uses 'YYYY-MM-DD' (e.g., 2023-10-05), while 'DD/MM/YYYY' (e.g., 05/10/2023) and 'MM/DD/YYYY' (e.g., 10/05/2023) are common in different regions

Formulas used in the calculator

While date calculators do all the calculations for you, understanding how each calculation works can help you better understand and intercept the results. Here are the formulas for all functions provided:

Adding Days to a Date

New Date = Start Date + Number of Days

The formula adds a specific number of days by transitioning across months and years accurately. It automatically adjusts for month lengths and leap years.

Example: March 1, 2025 + 10 days = March 11, 2025.

Subtract Days from a Date

New Date = Start Date - Number of Days

This formula moves backward in time, transitioning into previous months and years as needed, while adjusting for varyious month lengths.

Example: April 15, 2025 - 20 days = March 26, 2025.

Duration Between Two Dates

Duration = Later Date - Earlier Date

Calculates total calendar days considering all month/year transitions accurately. Each day is counted in full.

Example: January 31, 2025 - January 1, 2025 = 30 days.

Holiday Name2025 Calendar2026 Calendar
New Year's DayJan. 1, 2025Jan. 1, 2026
Martin Luther King Jr. DayJan. 20, 2025Jan. 19, 2026
President's DayFeb. 17, 2025Feb. 16, 2026
Memorial DayMay. 26, 2025May. 25, 2026
Juneteenth DayJun. 19, 2025Jun. 19, 2026
Independence DayJul. 4, 2025Jul. 4, 2026
Labor DaySep. 1, 2025Sep. 7, 2026
Columbus DayOct. 13, 2025Oct. 12, 2026
Veteran's DayNov. 11, 2025Nov. 11, 2026
ThanksgivingNov. 27, 2025Nov. 26, 2026
ChristmasDec. 25, 2025Dec. 25, 2026

Table 1 shows the holiday schedules for 2025 and 2026, ideal for planning your date-based tasks and duration tracking.

How to use this date calculator

1

Adding Days: Choose the 'Add/Subtract' mode, enter your start date, ensure 'Add Time' is selected, and input your years/months/days. Press calculate.

2

Subtracting Days: Switch to 'Subtract Time', enter the years or days to go back, and the tool will project the earlier date accurately.

3

Duration Between: Switch to 'Duration' mode, set your Earlier and Later dates, and get the exact split in years, months, weeks, and total days.