# GRP calculator

> Free GRP calculator: estimated gross rating points from gross impressions and a universe, or from a list of ratings, plus average frequency.

Source: https://psareach.com/tools/grp-calculator/

Free calculator

Work out estimated gross rating points for a PSA schedule. Divide gross estimated impressions by the audience universe, or add up the rating points airing by airing.

`Estimated GRP = gross impressions ÷ universe × 100Estimated GRP = Σ airings × rating`

## Your schedule

Example figures are filled in. Replace them with yours.

Calculate from

 Impressions and universe A list of ratings

Gross estimated impressions

Every exposure counted, across all airings.

Audience universe

Households or people in the market and demographic.

Estimated reach (%) (optional)

Share of the universe reached at least once, from audience data.

## Results

Estimated GRP Estimated

300.0

Gross impressions ÷ universe × 100

Estimated gross impressions Estimated

1,920,000

The figure you entered

Average frequency Estimated

4.0

GRP ÷ reach (%)

People or households reached Estimated

480,000

Reach (%) ÷ 100 × universe

GRP counts exposures, not people. Reach has to come from audience data, so enter it only if you have an estimate.

## How it is calculated

The same formulas as the methodology page and the reach and frequency guide.

[Read the full guide](https://psareach.com/insights/how-reach-and-frequency-are-calculated/)

`Estimated GRP = Gross estimated impressions ÷ Universe × 100` `Rating points per row = Airings × Rating` `Estimated GRP from a list = Sum of every row` `Estimated gross impressions = GRP ÷ 100 × Universe` `Average frequency = GRP ÷ Reach (%)` `Estimated reach = Reach (%) ÷ 100 × Universe`

**GRP counts exposures, not people.** A household that sees the PSA five times counts five times. That's why GRP adds up across weeks, stations and markets, and why it can't give you reach on its own.

**Keep one universe for the whole schedule.** Ratings, impressions and reach have to share a base: households, or a target group such as adults 25 to 54. With a target-group base, the result is an estimated TRP.

## Questions about the calculator

Can't find what you need here? Ask us directly.

[Talk to PSAReach](https://psareach.com/contact/)

What is the difference between GRP and TRP?

The arithmetic is the same. GRP usually uses all households as the universe, and TRP uses a defined target group such as adults 25 to 54. Enter target-group impressions and a target-group universe and the result is an estimated TRP.

Why is the GRP labeled estimated?

For donated broadcast, ratings and impressions are modeled from audience research, not counted. The GRP inherits that, so we label it estimated. If an audience vendor measured the impressions, you can say so.

Can I work out reach from GRP?

Not accurately. GRP counts the same people more than once, so reach has to come from audience data. If you have a reach estimate, enter it and the calculator gives you the average frequency.

Can I add GRP across stations and weeks?

Yes. GRP is a gross measure, so it adds across weeks, stations and markets, as long as every figure uses the same kind of universe. Reach doesn't add up that way.

## Other calculators

-   [Donated media value calculator Estimate the commercial-equivalent value of donated airings, with the formula shown. Open](https://psareach.com/tools/donated-media-value-calculator/)
-   [CPM and impressions calculator CPM from value and impressions, or impressions from a CPM. Open](https://psareach.com/tools/cpm-calculator/)
-   [All calculators The three free tools, with the formula behind each. Open](https://psareach.com/tools/)

## Want GRP and reach from verified airings?

We start from each verified airing and report estimated GRP, reach and frequency, with the method named.

[Talk to PSAReach](https://psareach.com/contact/) [See a sample report](https://psareach.com/sample-report/)