Audience growth calculator
Total audience growth and the average rate for one period.
Fill in the fields and the result will appear here automatically.
Two numbers describe the same growth and answer different questions. Total growth says how much larger the audience became; growth per period says what pace would produce that same result if it were spread evenly. Doubling over a year and doubling over a month share a total figure and have nothing else in common, which is why comparing channels on total growth alone is misleading. The per-period rate is what makes accounts of different ages comparable, and the net gain keeps the percentages honest — a hundred per cent on a base of twelve is twelve people.
How it works
Formula and logic
Total growth = (E/S − 1) × 100%. Per-period growth = ((E/S)^(1/n) − 1) × 100%, with positive whole audience counts S and E and duration n ≥ 1 in equal period units. This is the constant geometric rate connecting two observations, not an average of observed monthly rates. Fractional duration is valid when the period unit is defined.
Example
Going from 12,000 to 18,500 over six periods is 54.17% in total and 7.48% per period.
Fields and units
- Audience at the start — unitless
- Audience at the end — unitless
- Number of periods — unitless
How to use
- — Enter the audience size at the start of the period.
- — Enter the audience size at the end.
- — Enter how many periods passed between the two measurements.
- — Keep the period unit consistent — months or weeks, but not both.
- — Use the same period unit and audience definition when comparing channels; duration can be fractional, people counts cannot.
Method and limitations
- Calculation method
- Formula and logic
- Data or methodology source
- Microsoft RRI: an equivalent rate from start, end and number of periods
- Limitation
- Two observations and an equivalent constant geometric rate; no prediction of future growth or causes.
FAQ
Why is the per-period rate lower than total growth divided by periods?
For positive growth over more than one period, the geometric rate is lower than total growth divided by periods because the base compounds. At one period they coincide; unchanged counts give zero. Do not apply the same inequality to decline without checking its sign.
Can this handle a shrinking audience?
Yes. If the end figure is below the start, both rates come out negative — an honest description of decline rather than a hidden zero.
What counts as a period here?
Whatever unit you measured in: a month, a week, a campaign. The calculator does not care, as long as the count and the two measurements refer to the same unit.
Why show the net gain as well?
Percentages hide the base. Growing from twelve to twenty-four is a hundred per cent and twelve people, and the gain column is what keeps that in view.