IPMT in WPS Spreadsheet: Interest Within a Fixed Payment

=IPMT(rate, per, nper, pv, [fv], [type])

Rate is the rate per payment period. Per is the payment index, from 1 through nper. Nper counts all payments; pv is the initial present value; fv is the balance intended after the last payment. WPS documents omitted fv as zero. Its type table identifies 0 or omission as end-period payment and 1 as beginning-period payment.

The lesson prints six argument names but one narrative sentence says “five parameters.” Its enumeration and formal signature contain six. The formulas here supply all six explicitly, using fv = 0 and type = 0. Beginning-period, nonzero-final-balance and invalid-input cases are not independently calculated here.

Use a hypothetical initial amount of 210, a rate of 0.1 per period and two end-period payments. The equal payment magnitude is 121, obtained from 210*0.1*(1.1)^2/((1.1)^2−1).

1. Enter 0.1 in B1, 2 in B2 and 210 in B3.
2. Enter payment numbers 1 and 2 in A6:A7.
3. In B6 use =IPMT($B$1,A6,$B$2,$B$3,0,0) and copy to B7.
4. Independent expectations are −21 and −11. Negative signs describe outgoing interest, not a negative interest rate.

The second interest amount is based on the remaining 110, not the original 210. A fixed rate therefore does not imply a fixed interest component.

For the 110 example the payment magnitude is 72: principal repayments are 50 and 60. Doubling the original principal to 420 doubles both payment and interest amounts while leaving the rate unchanged.

In the first schedule the two interest magnitudes total 32, and the two payments total 242. The difference, 210, equals the principal repaid. Compare a whole payment with PMT and an interval’s interest with CUMIPMT. Principal-only PPMT answers a different component question.

Use full internal precision during a longer schedule; rounding every balance early can change later interest. Currency formatting only changes display. Real contractual rounding, fees, variable rates and irregular payment dates need their own model.

The official walkthrough uses 8%/12, payment 1, 512 periods and present value 12000, displaying −80. The first-period arithmetic is exactly −120000.08/12. This verifies the units and sign convention in that published example.

For monthly payments, nper must count months and rate must be a monthly rate. Dividing a quoted nominal annual rate by 12 is the lesson’s example convention; it is not a general conversion of an effective annual yield. Per outside 1 through nper violates the documented input definition, but the lesson does not supply a complete invalid-input error table. Do not infer specific errors or rounding rules from another spreadsheet product.

The official WPS lesson is dated 2019-06-10 and explicitly labels WPS Office for Windows Personal. Its numeric build is unspecified. This documents the function by that date; it does not establish first introduction, the last functioning build, other-platform parity or a retirement/deprecation history.

The complete lesson and its formula images and walkthrough were inspected on October 18, 2026. Original examples are documentation-derived independent calculations, not WPS or other spreadsheet-engine executions. These fictional financial calculations explain a function, not the suitability of a financial product.