Summary

The Excel CUMIPMT function returns the cumulative interest paid on a loan between two periods. Microsoft defines it specifically as cumulative interest, which means the function isolates financing cost and excludes principal reduction.

That distinction matters in amortization work. A level-payment loan contains both interest and principal in every payment, but the mix changes over time. CUMIPMT lets you total only the interest portion for a selected range of periods.

This makes the function useful for loan review, refinancing analysis, cost-of-debt reporting, and any model that needs to compare financing burden across different segments of the repayment term.

Syntax

=CUMIPMT(rate, nper, pv, start_period, end_period, type)

rate is the interest rate per period, nper is the total number of periods, pv is the original loan amount, start_period and end_period define the range to total, and type indicates payment timing.

As Microsoft documents, the period numbers must be integers, and the same time unit must be used consistently for rate, term, and selected periods. A monthly loan requires a monthly rate and monthly start and end periods.

Arguments

• rate - Interest rate per payment period.
• nper - Total number of periods in the loan.
• pv - Present value, or original principal.
• start_period - First period to include in the interest total.
• end_period - Last period to include in the interest total.
• type - Payment timing: 0 for end of period, 1 for beginning of period.

Under Excel's default sign convention, CUMIPMT often returns a negative amount because interest payments are cash outflows from the borrower's perspective. That negative sign is expected and should not be mistaken for an error.

CUMIPMT vs Other Functions

CUMIPMT is closely related to PMT, IPMT, and CUMPRINC, but it solves a narrower question: how much interest was paid over a defined window?

Use CUMIPMT when the worksheet needs interest aggregated across a period range rather than only a single-period split.

Using the CUMIPMT Function

CUMIPMT is common in mortgage and loan analysis because it shows how financing cost behaves over time. Early loan windows often contain much more interest than later windows because the outstanding balance is still large.

That makes the function helpful for refinance reviews, debt-cost summaries, and any schedule where the user needs to compare the cost of carrying the same loan at different stages.

• Use CUMIPMT when the question is about total interest over a selected range.
• Keep the period unit consistent across rate, term, and period arguments.
• Interpret negative values as cash paid out, not as a formula problem.

Example 1 - First-Year Interest

This formula sums all interest paid in the first 12 months of a 30-year loan. It is useful for measuring the early financing burden, when a large share of each payment still goes to interest rather than principal.

=CUMIPMT(0.05/12,360,100000,1,12,0)

Example 2 - Second-Year Audit

Calculating periods 13 through 24 isolates the second year's interest cost. Comparing this result with the first year shows the typical decline in interest as the loan balance is gradually repaid.

=CUMIPMT(0.05/12,360,100000,13,24,0)

Example 3 - Interest Threshold Check

This logical test checks whether the first-year interest total is more negative than -10000. The negative comparison is intentional because the function usually returns cash outflows as negative values.

=CUMIPMT(0.05/12,360,100000,1,12,0)<-10000

Example 4 - Interest-to-Loan Ratio

Wrapping the result in ABS removes the sign so the interest total can be expressed as a positive share of the original principal. This makes the result easier to compare across loans of different sizes.

=ABS(CUMIPMT(0.05/12,360,100000,1,12,0))/100000

Conclusion Recap

• Summary: CUMIPMT returns cumulative interest paid between two periods.
• Syntax: =CUMIPMT(rate,nper,pv,start_period,end_period,type).
• Core setup: Keep time units aligned and expect negative results under the default loan sign convention.
• Best use: Financing-cost analysis, amortization reviews, and interest-window comparisons.