Translate a rate into a time horizon.
Doubling time solves for the number of equal periods needed for a quantity to become twice as large at a constant compound growth rate. The logarithmic formula is exact for this model, unlike the approximate Rule of 72.
The rate and time unit must match. Five percent monthly growth doubles over a very different calendar horizon from five percent yearly growth. Neither result implies the rate can be maintained.
The formula, made clear.
- Growth rate
- Positive growth in each equal interval.
- Doubling time
- A fractional number of those intervals, not automatically years.
Put the numbers in context.
At 5% compound growth per period, doubling takes about 14.21 periods. At 5% monthly growth, that is about 14.21 months.
| Input | Example value |
|---|---|
| Growth per period | 5% |
| Periods required to double | 14.21 |
What this calculation assumes
Constant positive compound growth; zero growth never doubles and has no finite doubling time. No capacity ceiling or external additions. The calculation uses the exact logarithmic relationship.
What to consider next.
Use a growth projection to inspect the implied scale, then compare it with your available market.
How we approach financial models →