Weeks Between Two Dates Calculator
Work out how many weeks and days lie between two dates. Besides whole weeks, extra days and decimal weeks, a table gives the first and last day of each week.
- Whole weeks13
- Extra days1
- Weeks as a decimal13.14
- Total days92
- Calendar weeks touched14
- ISO week of the startWeek 45 (2026)
- ISO week of the endWeek 5 (2027)
Week by week
How it is calculated
Weeks are the total days divided by 7: every 7 days count as a week whatever weekday the range starts on. So the result can differ from the number of Monday-to-Sunday calendar weeks, which is shown separately as “calendar weeks touched”. Gestational age is set from the first day of the last menstrual period or an early ultrasound (ACOG Committee Opinion 700); use the pregnancy week calculator for that.
Whole weeks = ⌊Days ÷ 7⌋; Days left over = Days mod 7Days: the difference between the dates (the start day is not counted). Calendar weeks touched: how many Monday-to-Sunday weeks the range passes through, both ends included.Example
From 1 January to 1 April 2025 is 90 days: ⌊90 ÷ 7⌋ = 12 weeks, with 90 − 84 = 6 days left over; 12.86 weeks as a decimal.
Frequently asked questions
What date is 12 weeks from today?
12 weeks are 84 days. To add days, weeks, months or years to a date, use the date calculator.
How many weeks are in a year?
A 365-day year is 52 weeks and 1 day; a leap year 52 weeks and 2 days. In ISO 8601 week numbering some years have 53 weeks.