PDURATION in Collabora Office: Solve the Number of Compound-Growth Periods
Use Collabora PDURATION for a single principal growing at a constant per-period rate, with clear units and an explicit correction to misleading help prose.
Verification status: See the evidence and test scope described in this guide. How formula examples are checked
Quick answer: =PDURATION(5%;1000;2000) has independently expected result approximately 14.206699083 periods. It solves how long a positive starting value takes to reach a positive target under constant compound growth without additional payments.
Syntax and source-confirmed equation
=PDURATION(Rate; PV; FV)
Rate is the constant rate per period. PV is the positive present value and FV is the positive future target. All three arguments are required. The current Collabora interpreter calculates LN(FV/PV)/LN(1+Rate) and rejects Rate<=0, PV<=0 or FV<=0.
The period unit comes from Rate. An annual rate produces a number of years; a monthly rate produces a number of months. There is no periodic-payment argument, so this is not an annuity savings calculation.
The dedicated help contains confusing text about dividing the rate by the calculated duration and deriving a payment from FV/duration. Those statements are not used here: they do not follow from the source-confirmed compound-growth equation. Rate is supplied per period, and dividing FV by the answer does not create a supported periodic-payment result.
Example 1: calculate a doubling time
Put 5% in B2, 1000 in B3 and 2000 in B4. In B6 enter =PDURATION(B2;B3;B4). The independent target is approximately 14.206699083.
In B7 use =B3*(1+B2)^B6 to reconstruct the target value; it should mathematically return 2000. Keep the unrounded period count for this inverse check.
The answer is not necessarily a whole number. If interest is only credited at whole period ends and the question asks for the first such endpoint at or beyond the target, =ROUNDUP(B6;0) gives 15 for this example. That rounding is an explicit timing policy, not part of PDURATION itself.
Example 2: reproduce the official principal and target
For Rate=4.75%, PV=25000 and FV=1000000, the independent result is approximately 79.490794699 periods. This agrees with the help’s rounded duration of 79.49.
Use =PDURATION(4.75%;25000;1000000), then verify =25000*(1+4.75%)^result. The quotient of 1000000 by that duration is not a payment produced by the function, and no contribution schedule can be inferred from it.
The growth assumption is hypothetical. A constant stated rate over many periods is a model input, not a prediction that such a rate will actually persist.
Advanced application: match monthly rate conventions
If a nominal annual rate is 6% with monthly compounding, the periodic rate is 6%/12. =PDURATION(6%/12;1000;2000) has independent target approximately 138.975721611 months, or 11.581310134 years after dividing the result by twelve.
If 6% were an effective annual rate instead, the corresponding monthly rate would be (1+6%)^(1/12)-1. Simple division would not preserve that effective annual convention. Label the rate type before converting its units.
Advanced application: interpret equal or smaller targets
With a positive Rate and FV=PV, the logarithmic ratio is zero, so the source equation returns zero periods. With FV<PV, it returns a negative mathematical duration.
For example, =PDURATION(5%;2000;1000) has independent result approximately −14.206699083. This is not a future waiting time for positive growth to shrink the principal. It indicates that the requested smaller target lies backward along the idealized growth curve. Validate FV>=PV if the worksheet is specifically a forward target-time model.
Errors and troubleshooting
Current source rejects zero or negative rates and nonpositive values. Do not use opposite signs for PV and FV here as though it were a cash-flow payment function; this particular equation requires both positive.
Check units, rate convention and whether extra payments exist. Such payments require a different model. The source observations are from a moving-main snapshot, not a pinned desktop binary or native run; exact error strings and extreme-value accuracy remain unverified.
Availability and verification
The exact function is documented in Collabora Office 26.04 desktop help. The snapshot was retrieved on 2026-10-13 and hash-verified on October 15, 2026. Desktop help does not establish Online or mobile support. First introduced release and last functioning version are unknown; the dedicated evidence does not establish them.
No native Collabora or WPS run occurred. Worked values are independent mathematical expectations, not verification of every native error, coercion or numerical limit. Formulas use English names and semicolon separators.
A current Collabora interpreter source snapshot retrieved October 15, 2026 corroborates the stated formula or input handling. It is a moving-main source snapshot rather than a pinned 26.04 binary or native application execution.