Syntax
YEARFRAC(start_date, end_date, [basis])
| Parameter | Description |
|---|---|
| start_date | Parameter of the YEARFRAC function. |
| end_date | Parameter of the YEARFRAC function. |
| [basis] | (Optional.) Parameter of the YEARFRAC function. |
Examples
Fraction of year
Formula
=YEARFRAC("2026-01-01", "2026-07-01")
Returns 0.5 — exactly half a year between January 1 and July 1 using the default US (NASD) 30/360 basis.
Prorate annual salary
Formula
=75000 * YEARFRAC("2026-03-15", "2026-12-31")
Calculates the prorated portion of a $75,000 annual salary from March 15 through year end. Returns approximately $59,375.
Actual/actual basis
Formula
=YEARFRAC("2026-01-01", "2026-07-01", 1)
Returns 0.4959... using actual/actual day count (basis 1), which accounts for the actual number of days and whether it's a leap year.
Common Errors
#VALUE!
Occurs when dates are invalid or the basis argument is not 0-4.
#NUM!
Occurs when the basis argument is outside the range 0-4 or dates are out of valid range.
Tips
Basis options
0=US 30/360 (default), 1=Actual/actual, 2=Actual/360, 3=Actual/365, 4=European 30/360. Finance professionals know which their instrument requires.
Prorating amounts
Multiply any annual figure by YEARFRAC to get the partial-year amount: annual_rent * YEARFRAC(move_in, move_out) = prorated rent.
Age in years with decimals
=YEARFRAC(birth_date, TODAY()) returns age as a decimal. More precise than DATEDIF for partial-year age calculations.
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