Excel like a finance pro.
Date function
DAYS360
Returns days between dates on a 360-day year, used in some interest calculations.
When to use it
Days between two dates on a 360-day year of twelve 30-day months, the convention some bond and interest calculations use. Method FALSE is US (NASD), TRUE is European.
The shape of it
- Syntax
=DAYS360(start_date, end_date, [method])
Worked examples
US method
=DAYS360(DATE(2025,1,31),DATE(2025,3,1)) → 31
January 31 is treated as the 30th.
Full year
=DAYS360(DATE(2025,1,1),DATE(2025,12,31)) → 360
A full year is 360 days.
Month ends
=DAYS360(DATE(2025,2,28),DATE(2025,3,31)) → 30
February 28 (month end) to March 31 counts one 30-day month.
Worth knowing
- Interest at 30/360: principal × rate × DAYS360(start,end)/360.
- YEARFRAC with basis 0 gives the same fraction of a year.
- Use actual days (DAYS) unless a contract says 30/360.
Where it goes wrong
- US and European methods differ on 31st dates; match the contract.
- Text dates return #VALUE!.
Related
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