Cost per Install

In advertising for an app, counting as far as the click tells you nothing about the outcome. A click puts someone on a store listing, and if the download never finishes, nothing has happened.

After Pagedeck shipped its mobile app, Ravi bought a campaign on a click basis. The clicks arrived as planned — 8,000 of them — and installs came to 1,900. Delivering people to the store listing was the platform's obligation; those people turning around on that screen was not covered by the contract. Paying per install moves that gap over to the platform. Installs are also recorded by the app stores, which makes them hard to dispute, and that's part of why the basis is so widely used.

Divide the money spent by the number of installs. Spend $2,300 and get 2,000 installs and each one cost about $1.15.

1. Define an install before anything else. Platforms differ on whether the unit is a completed download or a first launch. Counting first launches lowers the number and raises the price, but what you're counting becomes people who actually opened the app.
2. Write down how reinstalls are handled. Counting someone who deleted the app and reinstalled it, or switched phones and installed again, as a new install inflates the count and makes the price look lower than it is.
3. The figure only exists once ad clicks and first launches are joined together. They're recorded in different places, so how long after a click an install still belongs to that ad is settled by the attribution window.
4. Break out the step after the install. If 600 of those 2,000 installs got past the first screen, the price of one person who uses the product is closer to $3.80. The network with the cheapest installs and the network that brings people who stay are frequently not the same one.
5. Web products have no equivalent. Without an install step, the basis is either clicks or one predefined action, which is cost per action (CPA).

"Installs are $1.15, but per account that gets past the first screen it's $3.80."

The price to an install and the price to someone who starts using the product are different numbers.

"This network counts downloads as installs and we count first launches."

The unit is defined differently, so the invoices won't reconcile.

"It's a web product, so cost per install doesn't apply — use signups."

Without the install step, a different basis fits.

The table Ravi produced after three months of app install ads had three columns: price per install, price per first launch, and price per account that created at least one document. The rankings in the three columns disagreed, and the column used to justify moving budget was the last one.