Days Between Dates Calculator

Should you count the end date?

A plain subtraction — the end date minus the start date — counts the start date and stops before the end date. That is the main number above. Add 1 when the last day is a full day too. Both numbers are always on the screen, so you only need to pick the right one:

If two tools disagree by one day, this is almost always why.

How to count the days yourself

1. Finish the first month. From March 20 to March 31 is 11 days (31 − 20).
2. Add the whole months in between at their real length: April 30, May 31.
3. Add the day of the last month. To June 10, add 10.
4. Add it up: 11 + 30 + 31 + 10 = 82 days, end date not counted. Add 1 if it should be.

The calculator does the same with day numbers for each date, so it is exact across years, leap days and daylight-saving changes. Open How it’s calculated under the answer to see each step.

Business days and federal holidays

Business days are Monday to Friday. With Skip federal holidays on, the 11 U.S. federal holidays are taken out on the day they are observed:

¹ The holiday falls on a weekend, so the day off moves: Saturday to the Friday before, Sunday to the Monday after (5 U.S.C. 6103, OPM). When January 1 is a Saturday, the day off is December 31 of the year before.

Rules from the U.S. Naval Observatory and OPM. State holidays (such as Cesar Chavez Day or Patriots’ Day) and company days off are not included. Holidays are counted from 1986, the first year all of today’s federal holidays except Juneteenth (2021) were in place.

Weeks and months between dates

• Weeks are days ÷ 7: 358 days is 51 weeks and 1 day.
• Months are counted the way a calendar does: from January 1, the 1st of each next month is one more month, and the days left over come last. January 1 to December 25 is 11 months and 24 days.
• Month ends: a start on the 31st lands on the last day of shorter months. January 31 to March 1, 2026 is 1 month (to February 28) and 1 day — 29 days in all.

Prorating rent or pay by the day

Moving in partway through a month, landlords usually charge the days you live there out of the days in that month. Moving in on October 20 with $1,550 rent: October 20 → 31, both dates counted, is 12 days, so the rent is 1,550 × 12 ÷ 31 = $600. The fraction calculator keeps 12/31 exact, and the share of the month — 38.7% — is one step in the percentage calculator. Some leases divide by 30 or by 365 ÷ 12 instead; the lease says which.

Days in each month and leap years

February has 29 days in a leap year: every year divisible by 4, except century years that are not divisible by 400. So 2024 and 2028 are leap years, 2000 was, and 1900 and 2100 are not (U.S. Naval Observatory). A year is 365 days, or 366 in a leap year.

Days between dates in Excel and Google Sheets

NETWORKDAYS counts both the start and the end date, so it matches this calculator with Count the end date too switched on. Put the observed holiday dates from the table above in H1:H11. Microsoft notes that DATEDIF “may calculate incorrect results under certain scenarios”, so check month counts here.

Counting days for deadlines

Many deadlines are counted differently from a calendar subtraction. Courts in the U.S. usually leave out the day of the event, count every day after it including weekends, and move the last day forward if it falls on a weekend or holiday. Rules vary by court and by state, so read the rule that applies to you — this calculator counts calendar days and business days, not legal deadlines.

To find the date a set number of days away — 90 days from today, 10 business days after an order — the date calculator is on the way, along with a time duration calculator for hours and minutes between two dates and times. To turn a count into a share of a year or a deadline, the percentage calculator does the division: 80 days out of 365 is 21.9%.