How do I calculate CPM?
To calculate CPM, divide the total cost of your ads by the number of impressions, then multiply by 1,000. CPM stands for cost per mille, Latin for thousand: it is the price you pay for 1,000 impressions. Take both numbers from the same campaigns and the same dates. In Meta Ads Manager, they are the amount spent and impressions columns, and Meta shows the result in its own CPM (cost per 1,000 impressions) column. If you spent $500 and your ads were shown 40,000 times, your CPM is $500 ÷ 40,000 × 1,000 = $12.50. The formula also works backward: multiply the CPM by the impressions and divide by 1,000 to get the cost, or divide the cost by the CPM and multiply by 1,000 to get the impressions. An impression counts each time an ad appears on screen, repeat views included, so CPM is not the price of reaching 1,000 different people.
What is the CPM formula?
Three versions of the same formula, one for each unknown, and two more for your clicks. Use the same campaigns and the same dates for every number.
- CPM
- = Cost ÷ Impressions × 1,000
- The price of 1,000 impressions.
- Cost
- = CPM × Impressions ÷ 1,000
- What a number of impressions costs at a given CPM.
- Impressions
- = Cost ÷ CPM × 1,000
- How many impressions a budget buys at a given CPM.
- CPC
- = Cost ÷ Clicks
- What one click costs. Ads Manager reports it as CPC (cost per link click).
- CTR
- = Clicks ÷ Impressions × 100
- The share of impressions that led to a click, in percent.
What does a CPM calculation look like?
These are example numbers, not a benchmark. A campaign spends $500 in a week. Its ads are shown 40,000 times and get 500 link clicks.
| Metric | Calculation | Result |
|---|---|---|
| CPM | $500 ÷ 40,000 × 1,000 | $12.50 |
| CPC | $500 ÷ 500 | $1.00 |
| CTR | 500 ÷ 40,000 × 100 | 1.25% |
| Cost per impression | $12.50 ÷ 1,000 | $0.0125 |
Each 1,000 impressions cost $12.50, so one impression costs $0.0125. With a CTR of 1.25%, one click costs $1.00.
How much do impressions cost at each CPM?
Use this table to turn a CPM into a cost, or a budget into impressions. The CPMs are round numbers for the math, not benchmarks.
| CPM | Cost of 10,000 impressions | Cost of 100,000 impressions | Impressions for $100 |
|---|---|---|---|
| $5.00 | $50 | $500 | 20,000 |
| $10.00 | $100 | $1,000 | 10,000 |
| $15.00 | $150 | $1,500 | ≈ 6,667 |
| $20.00 | $200 | $2,000 | 5,000 |
| $30.00 | $300 | $3,000 | ≈ 3,333 |
Impressions are rounded to the nearest whole number where the division does not end.
Is a low CPM a good sign?
Not on its own. CPM tells you what attention costs, not what it earns. A cheap audience that never buys costs more per sale than a pricier one that does. Once you know your CPM, check what those impressions brought back: your ROAS, and the break-even ROAS your margin allows.