How to Calculate CPM (Cost Per Mille)

To calculate CPM, open the CPM Calculator, choose what you're solving for under Solve for — CPM, Total cost, or Impressions — fill in the other two fields, and read the result along with the cost per impression.

What CPM means and why it matters

CPM stands for cost per mille — "mille" being Latin for a thousand — so it's the price an advertiser pays for every 1,000 ad impressions. It's one of the most common ways display, video, and social ads are priced, because it lets you compare campaigns of very different sizes on the same footing: a $500 campaign that delivers 40,000 impressions has the same CPM as a $5,000 campaign that delivers 400,000. The formula is CPM = (total cost ÷ impressions) × 1,000, and the CPM Calculator rearranges that same formula depending on which value you're missing.

How to calculate CPM with Toolbench

1. Open the CPM Calculator.
2. Under Solve for, pick the value you don't already know: CPM, Total cost, or Impressions.
3. Fill in the two fields that remain. If you're solving for CPM, enter Total cost (default 500) and Impressions (default 40000). If you're solving for Total cost, enter CPM (cost per 1,000) (default 12.5) and Impressions. If you're solving for Impressions, enter Total cost and CPM (cost per 1,000).
4. Read the main result, then check the rows below it for CPM, Total cost, Impressions, and Cost per impression together.

The calculator only shows the two fields it needs — the field you're solving for is hidden since it's the output, not an input.

A real worked example

With Solve for set to CPM, a $500 total cost, and 40,000 impressions:

Field	Value
CPM	12.50
Total cost	500.00
Impressions	40,000
Cost per impression	0.0125

That's $500 ÷ 40,000 impressions × 1,000 = $12.50 CPM — you're paying $12.50 for every 1,000 impressions, or $0.0125 per single impression.

Now flip it around. Say you know your CPM is $12.50 and your budget is $500, but you want to know how many impressions that buys: switch Solve for to Impressions, enter Total cost = 500 and CPM (cost per 1,000) = 12.5, and the calculator gives you back 40,000 impressions — the same relationship, solved in the other direction.

Tips and common mistakes

• CPM is per 1,000 impressions, not per impression. A $12.50 CPM means $0.0125 per single impression — easy to misread if you're mentally dividing cost by impressions without the ×1,000 step.
• Pick "Solve for" based on what you don't know, not what you want to check. If you already have all three numbers and just want to verify them, any mode will recompute the same relationship — the mode only decides which field is treated as the unknown.
• Use Cost per impression to sanity-check big numbers. When impressions run into the hundreds of thousands, the Cost per impression row (shown to five decimal places) is often easier to reason about than CPM alone.
• Compare CPMs across campaigns, not raw costs. A $2,000 campaign isn't automatically more expensive than a $500 one — compare their CPMs to see which is actually paying more per impression.

Related tools

• Margin Calculator — profit margin and markup from cost and price, useful once you know your ad spend and want to check it against revenue.
• Discount Calculator — sale price after one or two stacked discounts, with optional tax.
• PayPal Fee Calculator — what you'll receive after PayPal's cut, for the revenue side of a campaign.
• Stripe Fee Calculator — the same receive/charge math for Stripe.

Frequently asked questions

What does CPM stand for?

CPM stands for cost per mille — "mille" is Latin for a thousand — meaning the cost an advertiser pays per 1,000 ad impressions.

How do I calculate CPM?

Divide total cost by the number of impressions, then multiply by 1,000: CPM = (cost ÷ impressions) × 1,000. The CPM Calculator does this automatically when you set Solve for to CPM and enter the cost and impressions.

How many impressions will my budget buy at a given CPM?

Switch Solve for to Impressions, enter your Total cost and CPM (cost per 1,000), and the calculator returns the impression count — the formula is impressions = (cost ÷ CPM) × 1,000.

What's the difference between CPM and cost per impression?

CPM is the cost per 1,000 impressions, while cost per impression is the cost of a single impression. The CPM Calculator shows both: divide the CPM by 1,000 and you get the cost per impression row it displays.

Is my data sent to a server?

No. The calculation runs in your browser as you type. If you're signed in, your inputs sync privately to your account; if you're signed out, nothing is saved anywhere.