marketing calculator

Cost Per Install (CPI) Calculator

Calculate cost per install and break down the full funnel from impressions through installs to Day-30 retained users.

Cost Per Install (CPI) = Total Ad Spend ÷ Number of Installs. Breaking the funnel down further, CTR = Clicks ÷ Impressions and Click-to-Install Rate = Installs ÷ Clicks reveal whether a high CPI comes from weak ad creative or a weak app store listing.

Quick actions: Save inputs, view saved runs, print, share, or export results

Saved Runs

Inputs

Total ad spend$

Impressions

Clicks

Installs

Day-30 retained users (optional)

Results

Cost Per Install (CPI)

$10.00

CTR (Clicks / Impressions)1.00%

CPC (Cost Per Click)$0.50

Click-to-Install Rate5.00%

Effective CPM$5.00

Day-30 Retention Rate40.00%

Cost Per Retained User$25.00

Tip

Save this page to check campaign CPI against benchmarks and diagnose whether a high CPI comes from weak creative, weak store listing, or weak targeting.

Formula

CPI and funnel formulas

CPI = Spend ÷ Installs. CTR = Clicks ÷ Impressions. Click-to-Install Rate = Installs ÷ Clicks. Cost Per Retained User = Spend ÷ Retained Users.

Breaking spend down across the full funnel shows whether a high CPI comes from weak ad creative (low CTR), a weak store listing (low click-to-install rate), or poor retention.

Step by step

How the calculation works

1Enter total ad spend, impressions, clicks, and installs for the campaign or period.
2Optionally enter how many of those installs were still active at your retention checkpoint (commonly Day 30).
3Review CPI alongside CTR and click-to-install rate to see which funnel stage needs attention.
4Compare Cost Per Retained User against CPI — a large gap between them signals a retention problem, not an acquisition problem.

Example

Worked example: same CPI, different problem

Campaign A: $1,000 spend, 200,000 impressions, 2,000 clicks (1% CTR), 100 installs → $10 CPI. Campaign B: $1,000 spend, 50,000 impressions, 2,000 clicks (4% CTR), 100 installs → also $10 CPI. Same CPI, but Campaign A has a weak-CTR ad problem while Campaign B's bottleneck lies elsewhere.

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marketing calculator

Cost Per Install (CPI) Calculator

Calculate cost per install and break down the full funnel from impressions through installs to Day-30 retained users.

Quick actions: Save inputs, view saved runs, print, share, or export results

Saved Runs

Inputs

Total ad spend$

Impressions

Clicks

Installs

Day-30 retained users (optional)

Results

Cost Per Install (CPI)

$10.00

CTR (Clicks / Impressions)1.00%

CPC (Cost Per Click)$0.50

Click-to-Install Rate5.00%

Effective CPM$5.00

Day-30 Retention Rate40.00%

Cost Per Retained User$25.00

Tip

Save this page to check campaign CPI against benchmarks and diagnose whether a high CPI comes from weak creative, weak store listing, or weak targeting.

Summary

Key output metrics

CPI

$10.00

Spend ÷ Installs.

Cost Per Retained User

$25.00

Spend ÷ users still active at your retention window.

CTR

1.00%

Ad quality signal.

Click-to-Install Rate

5.00%

Store listing conversion signal.

D3 visualization

Funnel: Impressions → Clicks → Installs → Retained

Where the funnel narrows most reveals whether the ad, the store listing, or retention is the weak link.

Guide

How to understand and use this calculator

CPI is one number that hides three different problems

Cost Per Install (CPI) is simply total ad spend divided by the number of installs it produced: CPI = Spend ÷ Installs. That single number is useful for budgeting, but it collapses three very different funnel stages into one figure — how many people saw the ad (impressions), how many of those clicked (CTR), and how many of those clicks converted to an actual install (click-to-install rate, sometimes called store-page conversion rate). Two campaigns can land on the exact same CPI for completely different reasons: one with a weak ad but a strong app store listing, another with a strong ad but a confusing store listing — and only breaking down the funnel reveals which lever to pull.

Where CPI actually goes wrong: a worked comparison

Campaign A: $1,000 spend, 200,000 impressions, 2,000 clicks (1% CTR), 100 installs (5% click-to-install rate) → CPI = $10. Campaign B: $1,000 spend, 50,000 impressions, 2,000 clicks (4% CTR), 100 installs (5% click-to-install rate) → also CPI = $10. Both campaigns land on identical $10 CPI, but Campaign A's ad creative is underperforming relative to its audience (1% CTR is low), while Campaign B's ad is working well (4% CTR) — the bottleneck in Campaign B is elsewhere, or the audience is simply smaller. Without the funnel breakdown, both would get the same 'fix the CPI' diagnosis, when they need opposite fixes.

CPI measures acquisition, not value — that's the real limitation

Global average CPI runs around $0.53 for Android and $1.24 for iOS, per AppsFlyer's benchmark data, but a low CPI is not automatically a good outcome. CPI counts every install equally, whether that user opens the app once and deletes it or becomes a paying long-term customer. This is why performance marketers pair CPI with a Day-30 (or Day-7) retention check and a cost-per-retained-user figure — a campaign with a higher CPI but meaningfully higher retention can be the better spend even though the headline number looks worse.

Reading the retention-adjusted numbers

Cost per Retained User = Spend ÷ (Installs that are still active after your retention window, e.g. Day 30). If 100 installs cost $1,000 (CPI = $10) but only 40 of them are still active 30 days later, the real cost per retained user is $1,000 ÷ 40 = $25 — two and a half times the headline CPI. That $25 figure is what actually belongs next to Customer Lifetime Value (LTV) when deciding whether a channel is profitable, not the raw CPI.

Related calculators

Working the mobile-store side of this funnel? The ASO Conversion Calculator breaks down store-listing conversion specifically. Comparing this channel's efficiency against paid acquisition elsewhere? See the Marketing CPA Calculator for cost-per-acquisition on non-install conversion events, and the Ad Revenue Calculator if the app itself is ad-monetized and you need to weigh acquisition cost against in-app ad revenue.

Related concepts

CPI (Cost Per Install)

Total ad spend divided by number of installs — the standard mobile acquisition cost metric.

Click-to-install rate

The percentage of ad clicks that convert into an actual app install, isolating store-listing performance from ad performance.

Cost per retained user

Spend divided by the number of installs still active after a defined window (commonly Day 30) — a better proxy for acquisition efficiency than raw CPI.

Frequently Asked Questions

What is the Cost Per Install (CPI) formula?+

CPI = Total Ad Spend ÷ Number of Installs. If $1,000 in spend produces 200 installs, CPI is $5.

What's a good CPI for a mobile app?+

It varies widely by category and platform, but global averages run around $0.53 for Android and $1.24 for iOS according to AppsFlyer benchmark data. Gaming and finance apps often run higher; utility apps often run lower.

Why do two campaigns with the same CPI perform differently?+

Because CPI collapses CTR (ad quality) and click-to-install rate (store listing quality) into one number. Two campaigns can reach the same CPI through very different funnel strengths, which only shows up when you break the funnel apart.

Is a lower CPI always better?+

Not necessarily. CPI measures acquisition cost, not user quality. A cheaper install that churns immediately can cost more per retained or paying user than a pricier install that sticks around — check retention alongside CPI.

What's the difference between CPI and CAC?+

CPI (Cost Per Install) counts every install, including users who never engage further. CAC (Customer Acquisition Cost) typically counts only users who reach a meaningful action, like a purchase or subscription — CAC is usually higher than CPI for the same campaign.

How is click-to-install rate different from CTR?+

CTR measures ad clicks ÷ ad impressions (did the ad get clicked). Click-to-install rate measures installs ÷ clicks (did the click actually convert once someone reached the app store listing) — a weak store listing shows up here even when CTR looks fine.

Should I optimize for CPI or cost per retained user?+

Cost per retained user is the more decision-useful number for budget allocation, since it reflects users still active after your retention window, not just users who briefly installed. CPI remains useful for quick campaign-level budgeting and comparisons within the same channel.

Formula

CPI and funnel formulas

CPI = Spend ÷ Installs. CTR = Clicks ÷ Impressions. Click-to-Install Rate = Installs ÷ Clicks. Cost Per Retained User = Spend ÷ Retained Users.

Breaking spend down across the full funnel shows whether a high CPI comes from weak ad creative (low CTR), a weak store listing (low click-to-install rate), or poor retention.

Step by step

How the calculation works

1Enter total ad spend, impressions, clicks, and installs for the campaign or period.
2Optionally enter how many of those installs were still active at your retention checkpoint (commonly Day 30).
3Review CPI alongside CTR and click-to-install rate to see which funnel stage needs attention.
4Compare Cost Per Retained User against CPI — a large gap between them signals a retention problem, not an acquisition problem.

Example

Worked example: same CPI, different problem

Related guides

Learn more about this calculation

Guide

Paid Media Metrics Guide: CPC, CPM, CTR, CPA, ROAS, and ROI in Plain English

Understand the paid media metrics that actually matter. Learn how CPC, CPM, CTR, CPA, ROAS, and ROI connect, when to use each one, and how to avoid reporting cheap traffic as business success.

Guide

Understanding Calculator Formulas: How DTC Turns Inputs into Results

Understand how Do The Calculation formulas are presented, what the explanation blocks mean, and how to verify calculator logic before using a result in a real decision.