Home › How Many Weeks Between Two Dates
To find the number of weeks between two dates, count the total days and divide by 7. Use the date calculator on this site to get the day count first, then divide. Or enter both dates and the result includes the weeks breakdown automatically.
People think in weeks. Project timelines are built in sprints. Pregnancy is measured in weeks. Class schedules, subscription billing cycles, court notice periods, and sports seasons all use weeks as their natural unit. When someone asks "how long until the deadline?" the answer "19 weeks" lands better than "133 days" for planning purposes, even if both are technically accurate.
Converting days to weeks is straightforward:
In a spreadsheet, with the day count in cell C1:
=INT(C1/7)=MOD(C1,7)Or, if you have dates directly in A1 and B1: =INT((B1-A1)/7) for complete weeks.
Two weeks is 14 days. One week is always 7 days, so the multiplication is constant and never varies by month or year. This is the only completely reliable multiplier in date arithmetic.
| Start date | End date | Total days | Weeks and days |
|---|---|---|---|
| January 1, 2026 | March 31, 2026 | 89 | 12 weeks, 5 days |
| June 21, 2026 | September 21, 2026 | 92 | 13 weeks, 1 day |
| January 1, 2026 | December 31, 2026 | 364 | 52 weeks, 0 days |
| March 15, 2026 | June 15, 2026 | 91 | 13 weeks, 0 days |
| June 21, 2026 | June 21, 2027 | 365 | 52 weeks, 1 day |
| February 1, 2024 | March 1, 2024 | 29 | 4 weeks, 1 day |
Notice that January 1 to December 31 gives 364 days, which is exactly 52 weeks. The year itself is 365 days (366 in a leap year), but January 1 to December 31 exclusive of the end date gives one fewer day.
90 days divided by 7 equals 12 weeks and 6 days. The math: 12 multiplied by 7 equals 84, leaving 6 days beyond the last complete week. This comes up often in legal contexts (90-day deadlines), health timelines, and financial quarter calculations.
A regular year has 365 days. Divide by 7: that gives 52 complete weeks with 1 day left over. A leap year has 366 days: 52 complete weeks with 2 days left over. This is why the same calendar date falls on a different day of the week each year, and why there is occasionally a 53rd week in a calendar year depending on how you define "week."
Gestational age is measured in completed weeks from the first day of the last menstrual period (LMP). A full-term pregnancy is 40 weeks. To find your current gestational age in weeks, count the total days from your LMP to today and divide by 7, taking the integer. For example, if the LMP was January 5, 2026, and today is June 21, 2026, that is 166 days, which equals 23 weeks and 5 days of gestation.
This is one of the most practical uses of week-based date math, and the date calculator gives you the day count to start from.
Agile software teams work in 1- or 2-week sprints. If a project must ship in 18 weeks, that is 18 sprints of 1 week each, or 9 sprints of 2 weeks each, or 126 calendar days. Knowing both the week count and the day count lets you place milestones on specific calendar dates, which is where the days-between calculator becomes useful again.
To find the raw day count between dates, see how to calculate the number of days between two dates. To count forward a set number of weeks, add 7 times the number of weeks to your start date using the add days to a date tool.
Two weeks is 14 days. One week is always 7 days, no matter the month or year.
Find the total days between the dates, then divide by 7. Take the integer part for complete weeks and the remainder for leftover days. In a spreadsheet: =INT((B1-A1)/7) for weeks, =MOD(B1-A1,7) for remaining days.
A regular year has 52 weeks and 1 day. A leap year has 52 weeks and 2 days. For most purposes, 52 weeks per year is the standard figure.
Weeks = (End date minus Start date) divided by 7. Round down for complete weeks. Use a spreadsheet formula like =INT((B1-A1)/7) with dates in A1 and B1.
90 days is 12 weeks and 6 days. Divide 90 by 7: 12 full weeks (84 days) with 6 days remaining.