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Financial function
PDURATION
Returns the number of periods for an investment to reach a value.
Rarely usedDifficulty 1400 · AdvancedUsage rank #355 of 520
When to use it
The number of periods for an investment to grow from one value to another at a fixed rate.
The shape of it
- Syntax
=PDURATION(rate, pv, fv)
Worked examples
Doubling time
=PDURATION(0.05,1000,2000) → 14.21
Doubling at 5% takes just over 14 years.
Small gain
=PDURATION(0.025,2000,2200) → 3.86
A 10% gain at 2.5% a year.
Rule of 72 check
=PDURATION(0.07,1,2) → 10.24
The rule of 72 says about 10.3; this is exact.
Worth knowing
- Equivalent to LN(target/present)/LN(1+rate).
- RRI answers the reverse question: the rate for a given number of periods.
- Introduced in Excel 2013.
Where it goes wrong
- #NUM! for a rate of 0 or negative, or non-positive values.
- Periods are in the same unit as the rate.
Related
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