This article describes the formula syntax and usage of the RATE function in Microsoft Excel.
Description
Returns the interest rate per period of an annuity. RATE is calculated by iteration and can have zero or more solutions. If the successive results of RATE do not converge to within 0.0000001 after 20 iterations, RATE returns the #NUM! error value.
Syntax
RATE(nper, pmt, pv, [fv], [type], [guess])
Note: For a complete description of the arguments nper, pmt, pv, fv, and type, see PV.
The RATE function syntax has the following arguments:

Nper Required. The total number of payment periods in an annuity.

Pmt Required. The payment made each period and cannot change over the life of the annuity. Typically, pmt includes principal and interest but no other fees or taxes. If pmt is omitted, you must include the fv argument.

Pv Required. The present value — the total amount that a series of future payments is worth now.

Fv Optional. The future value, or a cash balance you want to attain after the last payment is made. If fv is omitted, it is assumed to be 0 (the future value of a loan, for example, is 0). If fv is omitted, you must include the pmt argument.

Type Optional. The number 0 or 1 and indicates when payments are due.
Set type equal to 
If payments are due 
0 or omitted 
At the end of the period 
1 
At the beginning of the period 

Guess Optional. Your guess for what the rate will be.

If you omit guess, it is assumed to be 10 percent.

If RATE does not converge, try different values for guess. RATE usually converges if guess is between 0 and 1.

Remarks
Make sure that you are consistent about the units you use for specifying guess and nper. If you make monthly payments on a fouryear loan at 12 percent annual interest, use 12%/12 for guess and 4*12 for nper. If you make annual payments on the same loan, use 12% for guess and 4 for nper.
Example
Copy the example data in the following table, and paste it in cell A1 of a new Excel worksheet. For formulas to show results, select them, press F2, and then press Enter. If you need to, you can adjust the column widths to see all the data.
Data 
Description 

4 
Years of the loan 

200 
Monthly payment 

8000 
Amount of the loan 

Formula 
Description 
Result 
=RATE(A2*12, A3, A4) 
Monthly rate of the loan with the terms entered as arguments in A2:A4. 
1% 
=RATE(A2*12, A3, A4)*12 
Annual rate of the loan with the same terms. 
9.24% 