NPER Function (OpenOffice Calc)

• Introduced: First release not established; documented by OpenOffice.org 3.3.
• Supported in: Apache OpenOffice 4.1.16; this is a verified release, not a final supported version.
• Scope: Desktop Calc, English function names and semicolon-separated formulas.
• Checked: October 14, 2026. Eight ordinary reference formulas were recalculated from generated ODF in 4.1.16 on Linux x86-64, Build 9816. Source and independent mathematics were also checked.

NPER solves the constant-rate cash-flow equation for the number of periods. A fractional answer is a solution of the annuity equation, not an instruction to issue a fraction of a regularly scheduled invoice. Rate and Payment must use the same period unit. Release implementation.

=NPER(Rate; Payment; PresentValue [; FutureValue [; Type]])

Rate, Payment and PresentValue are required. FutureValue defaults to 0 and Type defaults to 0. Type=1 means beginning-period payments; supply the preceding FutureValue explicitly. The source uses the beginning branch for positive Type. Use 0 or 1 to express the two intended timings.

The native column contains saved 4.1.16 results; the independent column uses high-precision mathematical calculations. Values are displayed to twelve decimal places, so harmless final-place differences remain visible. Rate decimals such as 0.05 represent 5%, not 0.05%.

A positive model balance of 1000 and outgoing payments of 100 per period at 1% uses =NPER(0.01;-100;1000). If its result lies between two integers, a real fixed-date schedule normally needs a separately computed final smaller payment. Rounding the NPER result upward does not itself calculate that final amount.

At zero interest, =NPER(0;-100;1200) gives exactly 12. A positive payment combined with a positive loan balance can solve a different signed equation, so do not repair an unexpected negative period count by taking ABS.

For end-period payments p and nonzero r, the source solves n=ln((p−r×FV)/(r×PV+p))/ln(1+r). For beginning-period payments, replace p by p×(1+r) inside that logarithmic ratio. The ratio and logarithm must have a meaningful real domain.

For pure growth with no payments, =NPER(0.05;0;-1000;2000) gives ln(2)/ln(1.05), approximately 14.206699082890 periods. The starting and ending amounts have opposite cash-flow signs. This is compound growth at an assumed fixed rate, not a forecast.

The zero-rate branch gives n=−(PV+FV)/p. A zero payment at zero rate cannot reduce a nonzero balance. At a positive rate, a payment no larger than accrued interest does not provide a finite positive payoff under the ordinary loan model; examine feasibility rather than hiding an error.

Period counts in the native table are unrounded. Use an explicit schedule when whole payment dates, changing rates, additional principal payments or irregular dates matter. The negative-rate example establishes one numerical case in the named release only. It does not establish every negative-rate, sign or logarithmic-boundary combination.

log, ln, ROUNDUP.

• Function-specific release entry

The generated ODF input produced the informational load warning “Not all attributes could be read.” After it was acknowledged, the sheet was hard-recalculated and saved separately. All eight ordinary function identities and results were reconciled; a stale SUM cache changed from 999999 to 3 and an uncached SUM returned 7. This establishes the stated formula examples, not every workbook style or every invalid input. The original XLSX was not executed. Other explanatory calculations are independent mathematical checks; this guide does not claim a fully executed amortization schedule, other releases or all boundary cases.