The equation you want is: `P = (Pv*R) / [1 - (1 + R)^(-n)]`

where

**P** = Monthly Payment
**Pv** = Present Value (starting value of the loan)
**APR** = Annual Percentage Rate
**R** = Periodic Interest Rate = APR/number of interest periods per year
**n** = Total number of interest periods (interest periods per year * number of years)

Using the variables above, the Excel =PMT() function is **=PMT(R,n,Pv)**

So, for your example where:

- rate (APR) = 4.75% (making
**R**=4.75%/12 or 0.0475/12)
- mortgage (
**Pv**) = 220000
- term (# of years) = 30 (
**n**=30*12 with monthly payments)

The equation becomes:

P = ((220000 * (0.0475/12)) / (1 - ((1 + (0.0475/12))^(-1 * 30 * 12))))

Or, with the original equation shown directly below it for comparison:

P = ((220000 * (0.0475/12)) / (1 - ((1 + (0.0475/12))^(-1 * 30 * 12))))
P = ( Pv * R ) / (1 - ( 1 + R )^( -n )

amortization calculatorin Wikipedia.