How to Calculate CPM: Formula and Examples

CPM means cost per thousand impressions. It shows the average media cost for 1,000 ad impressions.

CPM = (Ad spend ÷ Impressions) × 1,000

If a campaign costs $500 and delivers 100,000 impressions, CPM is $5. Use the CPM Calculator for a quick calculation.

CPM formula

You need ad spend and impressions measured for the same campaign and date range.

1. Divide spend by impressions.
2. Multiply by 1,000.

Example with $1,200 spend and 240,000 impressions:

(1,200 ÷ 240,000) × 1,000 = 5

The result is $5 CPM.

Calculate total cost from CPM

If CPM and impressions are known, rearrange the formula:

Ad spend = (CPM × Impressions) ÷ 1,000

At an $8 CPM, 250,000 impressions would cost:

(8 × 250,000) ÷ 1,000 = $2,000

This is a planning estimate. Actual delivery can vary as inventory and auction conditions change.

Calculate impressions from CPM and budget

If budget and CPM are known:

Impressions = (Ad spend ÷ CPM) × 1,000

A $1,500 budget at a $6 CPM corresponds to:

(1,500 ÷ 6) × 1,000 = 250,000 impressions

CPM vs CPC

CPM measures cost per 1,000 impressions. CPC measures cost per click.

A campaign can have a low CPM but a high CPC if few impressions turn into clicks. Use the CPC Calculator to calculate average cost per click.

CPM vs CTR

CTR measures the percentage of impressions that generated clicks:

CTR = (Clicks ÷ Impressions) × 100

CPM tells you how expensive the impressions were; CTR tells you how often impressions became clicks. Use the CTR Calculator for that ratio.

How CPM, CTR and CPC connect

Suppose a campaign has 100,000 impressions, $500 spend, and 1,000 clicks.

• CPM: (500 ÷ 100,000) × 1,000 = $5
• CTR: (1,000 ÷ 100,000) × 100 = 1%
• CPC: 500 ÷ 1,000 = $0.50

These metrics answer different questions, so reviewing them together gives more context than optimizing one number in isolation.

CPM vs ROAS

ROAS compares attributed advertising revenue with ad spend. CPM is a delivery-cost metric, while ROAS is a revenue-efficiency metric.

A low CPM does not guarantee strong revenue performance. Use the ROAS Calculator when attributed revenue is available.

What is a good CPM?

There is no universal good CPM. Results vary with platform, audience, placement, location, season, campaign objective, and competition.

A useful benchmark is your own comparable campaign history. Evaluate CPM alongside CTR, CPC, conversions, and ROAS rather than assuming the cheapest impressions are automatically the best.

Common CPM mistakes

Forgetting the factor of 1,000

Spend divided by impressions is cost per individual impression. Multiply by 1,000 to express CPM.

Mixing scopes or date ranges

Spend and impressions must refer to the same reporting scope and period.

Treating impressions as unique people

One person can generate multiple impressions. Impressions and unique reach are different measurements.

Optimizing only for low CPM

Cheap impression delivery can still produce weak clicks, conversions, or revenue. Match the metric to the campaign objective.

FAQ

What does CPM stand for?

CPM is commonly used for cost per thousand impressions.

Is lower CPM always better?

No. Lower CPM means cheaper impression delivery, not necessarily better audience quality or business outcomes.

Can I calculate spend from CPM?

Yes. Multiply CPM by impressions and divide by 1,000.

Can I calculate impressions from CPM?

Yes. Divide spend by CPM and multiply by 1,000.

Calculate CPM

Enter spend and impressions in the CPM Calculator, then compare the result with CPC, CTR, and ROAS when those metrics are relevant.