PRIVATE, BROWSER-ONLY WORKSHEET · Calculators
Reverse Growth Base Value Finder
Find a starting value from a known final value, constant per-period growth rate, and number of compounding periods.
A final value of 121 after two periods of 10% growth began at 100, because 100 × 1.1 × 1.1 = 121.
Set up the calculation
Enter your own values or load the worked example. Your entries stay in this browser.
Your result
Starting value
UNDERSTAND THE RESULT
How to use the Reverse Growth Base Value Finder
Use this to reconstruct an earlier baseline from a later measurement under an explicitly assumed constant growth rate. It is useful for planning checks, not a historical proof.
What to enter
Enter the positive final value, growth percentage per period, and whole number of equal periods. Use -10 for a 10% decline per period.
Worked example
A final value of 121 after two periods of 10% growth began at 100, because 100 × 1.1 × 1.1 = 121.
How to read the result
The starting value is the amount before the first growth period. The table repeats the factor and number of periods so you can check the model.
Method
Divide the final value by (1 + rate/100) raised to the entered number of periods. A negative rate is allowed as long as each per-period factor remains positive.
What to check
This is a constant-rate mathematical model. It excludes cash flows, fees, irregular periods, and changing growth rates.
Avoid this mistake
Subtracting the stated growth percentage from the final value ignores compounding and gives the wrong starting base.
Calculations run locally in your browser. No entered values are sent to the Nirmion API.
Questions to check
Can the rate be negative?
Yes. A rate above -100% models repeated decline while retaining a positive factor.
What does one period mean?
It is whatever consistent interval your rate uses: month, quarter, or year. The tool does not assume a calendar interval.
Can I use different rates each period?
No. This worksheet applies one fixed rate; calculate changing periods separately.