PDURATION in WPS Spreadsheet: Find the Number of Growth Periods

=PDURATION(10%,100,121) has the independently expected result 2 periods. At a constant 10% per period, 100 grows to 110 after one period and 121 after two. The result’s time unit comes from the rate: an annual rate gives years; a monthly rate gives months.

PDURATION(rate, pv, fv)

Supply the per-period growth rate, the present amount pv and the target amount fv, in that order. No optional arguments or defaults are shown. These examples use strictly positive rates and amounts with a target above the initial amount. They do not import cash-flow sign conventions from other financial functions.

In B6 enter =PDURATION(B2,B3,B4). Expected result: 2. Format B6 as a number, not a percentage or date. An independent mathematical check is ln(121/100) ÷ ln(1.10), which equals 2 apart from floating-point rounding. In B7, the ordinary formula =B3*(1+B2)^B6 should reconstruct the target 121 under the model.

The function answers a duration question. It does not predict when an uncertain real-world return will arrive, nor does it automatically account for later contributions.

Change B4 to 150 while leaving B2 and B3 unchanged. =PDURATION(B2,B3,B4) is independently expected to return approximately 4.25416371 periods. The logarithmic check is ln(1.5) ÷ ln(1.1).

If your model only credits growth at whole-period boundaries, check the neighboring whole periods explicitly: =B3*(1+B2)^4 gives 146.41, while =B3*(1+B2)^5 gives 161.051. Five whole periods reach or exceed 150; simply rounding the fractional result to the nearest integer would give four and miss the target. This is a modeling decision about when growth is credited, not an extra PDURATION argument.

For another exact control, =PDURATION(5%,1000,1157.625) is expected to return 3. The target was constructed as 1000 × 1.05³.

• Check the order rate, pv, fv. Swapping the two amounts changes the question.
• Enter 10% or 0.10 for ten percent. Entering 10 represents a rate of 1000%.
• Keep the rate period consistent. Dividing an effective annual rate by 12 does not generally produce the equivalent compounded monthly rate.
• The WPS FAQ suggests inspecting text, spaces and invalid characters for #VALUE!. A numeric display format alone does not guarantee the cell stores a number.
• The reviewed sources do not settle exact zero-rate, zero-value, negative-value or sign-boundary error behavior. Those cases are outside these examples; no exact error label is claimed for them.
• Constant growth without intervening payments is the model used here. Use an appropriately specified model for deposits, withdrawals, fees or changing rates.

See NPER for a different financial function with a payment argument, and LN for the logarithm used in the independent check.

The official Windows documentation was checked on October 19, 2026: introduction, entry and syntax guide, and troubleshooting FAQ. These pages carry a July 13, 2026 update date and describe this function as available without membership. That date is not an introduction date; the documentation does not identify an exact minimum build. This guide does not infer support in historical builds, other editions, or Mac, Linux, web and mobile apps. The examples are independently calculated expectations, not observed WPS outputs. Native execution and genuine application screenshots remain unverified.

These are fictional mathematical examples for learning a spreadsheet function, not investment recommendations or forecasts.

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