# CPM Formula: How to Calculate Cost per Thousand Impressions

- URL: https://betteranalyst.com/metrics/cpm
- Published: 2026-10-30
- Updated: 2026-10-30
- Author: David Bressler, Founder (https://betteranalyst.com/authors/david-bressler)

> **Summary:** CPM = Ad spend ÷ Impressions × 1,000. It is the cost of 1,000 ad impressions and the standard way to compare reach costs across channels. A $14,500 awareness campaign that delivered 1,527,000 impressions had a blended CPM of $9.50.

Category: [Marketing](https://betteranalyst.com/metrics#marketing)

CPM formula with a three-placement awareness campaign, the Excel formula, how to plan impressions from a budget, and when CPM comparisons mislead.

## Cost per mille (CPM) formula

```
CPM = Ad spend ÷ Impressions × 1,000
```

- **Ad spend**: Media cost for the placement and period.
- **Impressions**: Number of times the ad was served. For video or audio, check whether the platform counts a served ad or a minimum view/listen.

## How to calculate cost per mille (CPM) in Excel and Google Sheets

Excel, using the cells in the worked example below:

```
=SUM(B2:B4)/SUM(C2:C4)*1000
```

## Worked example

A regional credit union ran a four-week awareness campaign for a new savings account across social, online video and streaming audio, and wants comparable reach costs.

*Four-week awareness campaign (table starts in cell A1)*

| Placement | Spend | Impressions |
| --- | --- | --- |
| Meta (Facebook + Instagram) | $4,800 | 812,000 |
| YouTube | $6,200 | 540,000 |
| Streaming audio | $3,500 | 175,000 |

1. Total spend = $14,500; total impressions = 1,527,000.
2. Blended CPM = 14,500 ÷ 1,527,000 × 1,000 = $9.50.
3. By placement (=B2/C2*1000 filled down): Meta $5.91, YouTube $11.48, streaming audio $20.00.
4. Planning: at a $9.50 CPM, a $20,000 budget buys 20,000 ÷ 9.50 × 1,000 = 2,105,263 impressions, about 2.1 million.

**Result:** $9.50 blended CPM

## How to interpret cost per mille (CPM)

CPM tells you what reach costs, not what it achieves. Formats differ: a mostly skippable social impression and a 30-second audio spot heard in full are not the same unit, so a higher CPM can still be the better buy. Use CPM to compare similar placements over time and to plan budgets, then judge outcomes with CTR, cost per acquisition or brand-lift studies. CPMs also move seasonally, typically rising in the fourth-quarter holiday period as more advertisers compete for the same audiences.

## Common mistakes

- Comparing CPM across formats as if impressions were equal. Normalise by viewable or completed impressions when you can.
- Forgetting the × 1,000. Spend ÷ impressions alone is cost per impression, a tiny number that is easy to misread.
- Averaging placement CPMs. Divide total spend by total impressions for the blended figure.
- Optimising for low CPM alone. The cheapest inventory is often the least seen or least relevant audience.

## Calculate cost per mille (CPM) with Better Analyst

Connect your data or upload a spreadsheet, then ask in plain English. Better Analyst writes and runs the calculation and shows the steps, so you can check the number.

- “Calculate CPM, CTR and CPA by placement for this campaign export.”
- “How many impressions can we buy with $20,000 at each placement's current CPM?”
- “Chart weekly CPM by channel for the last 12 months to show seasonality.”

Usually calculated from: [Google Sheets](https://betteranalyst.com/data-connectors/google-sheets), [Google BigQuery](https://betteranalyst.com/data-connectors/bigquery), [Snowflake](https://betteranalyst.com/data-connectors/snowflake), [Google Analytics](https://betteranalyst.com/data-connectors/google-analytics).

[Try Better Analyst free](https://betteranalyst.com/signup)

## Further reading

- [ROAS formula](https://betteranalyst.com/metrics/roas)
- [SUMPRODUCT function](https://betteranalyst.com/excel/sumproduct-function)
- [How to divide in Excel](https://betteranalyst.com/excel/how-to-divide-in-excel)
- [Better Analyst for marketing teams](https://betteranalyst.com/solutions/marketing-teams)

## Frequently asked questions

### What does CPM stand for?

Cost per mille, from the Latin for thousand. It is the price of 1,000 impressions.

### How do I calculate impressions from a CPM and budget?

Impressions = Budget ÷ CPM × 1,000. A $5,000 budget at a $12.50 CPM buys 400,000 impressions.

### What's the difference between CPM and CPC?

CPM is cost per 1,000 impressions; CPC is cost per click. They are linked by CTR: CPC = CPM ÷ (CTR × 1,000). A $10 CPM with a 1% CTR works out to a $1.00 CPC.

## Related metrics

- [Click-Through Rate Formula: How to Calculate CTR (Excel)](https://betteranalyst.com/metrics/click-through-rate)
- [ROAS Formula: How to Calculate Return on Ad Spend (Excel)](https://betteranalyst.com/metrics/roas)