CPM Calculator: Cost per 1,000 Impressions

Work out the cost of 1,000 ad impressions — or work backwards from a CPM to find the cost or the impressions. Pick what you want to find, enter the two numbers you know, and the calculator gives the answer instantly. It runs entirely in your browser: free, instant, no sign-in.

Total cost ($)

Impressions

How the CPM calculator works

CPM stands for cost per mille — the cost of 1,000 ad impressions. Mille is Latin for a thousand, so a CPM of $2.00 means every 1,000 times your ad is shown costs you $2.00. The calculator has three modes, all built on the same relationship between cost, impressions and CPM:

Find CPM: CPM = cost ÷ impressions × 1,000. A $500 campaign that reaches 250,000 impressions gives $500 ÷ 250,000 × 1,000 = $2.00 CPM.
Find cost: cost = CPM × impressions ÷ 1,000. A $4.00 CPM for 100,000 impressions costs $4.00 × 100,000 ÷ 1,000 = $400.00.
Find impressions: impressions = cost ÷ CPM × 1,000. A $250 budget at a $5.00 CPM buys $250 ÷ $5.00 × 1,000 = 50,000 impressions.

Money results are rounded to the nearest cent and CPM to two decimals; impressions are shown as a whole number, because an ad cannot be shown a fraction of a time.

Every ad platform quotes its prices in CPM — cost per mille, the cost of 1,000 impressions — but campaigns are planned in budgets and audience sizes, so someone has to do the conversion. The CPM Calculator does it for you, in either direction. Enter the two numbers you know and it finds the third: the CPM from a cost and an impression count, the total cost from a CPM and an impression count, or the impressions a budget will buy at a given CPM. It updates as you type, rounds money to the nearest cent and impressions to a whole number, and runs entirely in your browser, so nothing you enter is uploaded anywhere and there is no sign-in and no limit on how often you use it.

The calculation is exact, not an estimate, because it is simple multiplication and division built on one relationship: cost = CPM × impressions ÷ 1,000. The dollar sign is used in the examples as a generic currency symbol — the maths is the same in any currency, so just read $ as your own currency when you use it.

How to use the calculator, step by step

There are three modes and two inputs. Everything updates live — there is no button to press.

Step 1 — Pick what you want to find. Tap “Find CPM” if you know the cost and the impressions, “Find cost” if you know the CPM and the impressions, or “Find impressions” if you know the cost and the CPM.
Step 2 — Enter the first number. For “Find CPM” and “Find impressions” this is the total campaign cost, for example 500 for a $500 campaign. For “Find cost” it is the CPM, for example 4 for a $4.00 CPM.
Step 3 — Enter the second number. For “Find CPM” and “Find cost” this is the number of impressions, for example 250000 for 250,000 impressions. For “Find impressions” it is the CPM.
Step 4 — Read the result. The big number is the answer, and underneath it the calculator shows the maths behind it, so you can check the figures at a glance. If a value is missing, zero or negative, the calculator says so instead of showing a fake result.

How the maths works

Three formulas sit behind the calculator, all rearrangements of the same relationship:

CPM = cost ÷ impressions × 1,000. A $500 campaign that reaches 250,000 impressions gives $500 ÷ 250,000 × 1,000 = $2.00 CPM.
Cost = CPM × impressions ÷ 1,000. A $4.00 CPM for 100,000 impressions costs $4.00 × 100,000 ÷ 1,000 = $400.00.
Impressions = cost ÷ CPM × 1,000. A $250 budget at a $5.00 CPM buys $250 ÷ $5.00 × 1,000 = 50,000 impressions.

The 1,000 is there because CPM is priced per thousand impressions, not per impression. A single impression at a $2.00 CPM costs $0.002 — two tenths of a cent — which is why advertisers quote the price per thousand instead. Money results are rounded to the nearest cent and CPM to two decimals, and impressions are rounded to the nearest whole number, because an ad cannot be shown a fraction of a time.

The table below shows the CPM for a $500 campaign at different audience sizes:

100,000 impressions — $5.00 CPM
250,000 impressions — $2.00 CPM
500,000 impressions — $1.00 CPM
1,000,000 impressions — $0.50 CPM

And the table below shows how many impressions a $1,000 budget buys at different CPMs:

$1.00 CPM — 1,000,000 impressions
$2.00 CPM — 500,000 impressions
$5.00 CPM — 200,000 impressions
$10.00 CPM — 100,000 impressions
$20.00 CPM — 50,000 impressions

Worked examples

Example 1 — $500 cost, 250,000 impressions. The CPM is $500 ÷ 250,000 × 1,000 = $2.00. Every 1,000 times the ad is shown costs $2.00.

Example 2 — $4.00 CPM, 100,000 impressions. The cost is $4.00 × 100,000 ÷ 1,000 = $400.00. Reaching 100,000 people at that rate costs $400.00 in total.

Example 3 — $250 cost, $5.00 CPM. The impressions are $250 ÷ $5.00 × 1,000 = 50,000. A $250 budget at a $5.00 CPM buys 50,000 impressions.

Example 4 — $100 cost, 10,000 impressions. The CPM is $100 ÷ 10,000 × 1,000 = $10.00. A small, tightly targeted audience usually costs more per thousand than a broad one.

Example 5 — Rounding. A cost of $333.333 rounds to $333.33, and a budget of $100 at a $3.00 CPM buys $100 ÷ $3.00 × 1,000 = 33,333.33 impressions, which rounds to 33,333 impressions. The calculator does this rounding for you — money to the nearest cent, impressions to the nearest whole number.

Common mistakes

Dividing by 100 instead of 1,000. CPM is per mille — per thousand — so the multiplier is 1,000. Dividing the cost by the impressions alone gives the cost of a single impression ($0.002 in the $500 example), which is not the CPM. Multiply by 1,000 to get the CPM.
Confusing CPM with CPC. CPM is the cost per 1,000 impressions — every time the ad is shown, whether or not anyone clicks. CPC is the cost per click. A campaign can have a low CPM and a high CPC at the same time if few people click, so compare like with like.
Confusing impressions with reach. Impressions count every time the ad is shown, including repeat views by the same person. Reach counts unique people. If one person sees your ad three times, that is 3 impressions and 1 reach — so a CPM worked out on reach instead of impressions will be wrong.
Forgetting that a higher CPM is not always worse. A $10.00 CPM on a narrow, well-targeted audience can be better value than a $2.00 CPM on a broad audience that never buys, because the expensive impressions reach people who actually convert. Judge a CPM by what the impressions produce, not by the number alone.
Using the budget before fees. Some platforms add fees or taxes on top of the spend. If the CPM is quoted on the platform’s spend but you pay fees on top, work out the CPM on the total amount that actually leaves your account — otherwise the real CPM is higher than the one you calculated.

Related tools

The CPM calculator sits in the Finance group, and three companion tools cover the rest of everyday money maths.

Percentage Calculator — work out any percentage, percentage increase or decrease, or what percentage one number is of another.
Discount Calculator — find the price after a discount and how much you save, for sales and markdowns.
Monthly Budget Calculator — plan your monthly income and spending so the ad budget fits the month.

For all of ToolZana’s free tools, start at the ToolZana home page.

Tips for using CPM well

Compare CPMs on the same audience. A $2.00 CPM on a broad audience and a $10.00 CPM on a narrow one are not directly comparable — the audiences are different products. Compare CPMs only between campaigns aimed at the same kind of people.
Work out the budget before you launch. Decide the impressions you want, multiply by the CPM and divide by 1,000, and you have the budget — a $4.00 CPM for 100,000 impressions needs $400.00. Agreeing the budget first stops a campaign overspending by accident.
Watch frequency, not just CPM. If the same people see your ad ten times, the CPM looks fine but the money is wasted on repeat views. Check how often each person sees the ad alongside the CPM.
Test a small budget first. Run a small test — $50 or $100 — and work out the real CPM from the actual cost and impressions before committing the full budget. Quoted CPMs are estimates; the calculator shows the real one.
Track what the impressions produce. CPM tells you what attention costs, not what it is worth. Divide the cost by the sales or sign-ups the campaign produced as well, so you know whether a cheap CPM is actually good value.

The short version

The CPM Calculator finds any one of cost, CPM and impressions from the other two: CPM = cost ÷ impressions × 1,000, cost = CPM × impressions ÷ 1,000, and impressions = cost ÷ CPM × 1,000. A $500 campaign reaching 250,000 impressions costs $2.00 per thousand. A $4.00 CPM for 100,000 impressions costs $400.00. A $250 budget at a $5.00 CPM buys 50,000 impressions. A $100 campaign reaching 10,000 impressions costs $10.00 per thousand. Money is rounded to the nearest cent, impressions to the nearest whole number, and the tool is free, runs entirely in your browser, and needs no sign-in.

Frequently Asked Questions

What is a CPM calculator?

A CPM calculator works out the cost per mille — the cost of 1,000 ad impressions — from a campaign’s cost and impression count. The ToolZana CPM calculator has three modes: find the CPM from cost and impressions, find the total cost from a CPM and impressions, or find the impressions a budget will buy at a given CPM. It updates as you type, rounds money to the nearest cent, and runs entirely in your browser.

How do I calculate CPM?

Divide the total cost by the number of impressions, then multiply by 1,000: CPM = cost ÷ impressions × 1,000. For example, a $500 campaign that reaches 250,000 impressions gives $500 ÷ 250,000 × 1,000 = $2.00 CPM. Enter the cost and the impressions in the calculator and it does the division and multiplication for you.

What is a good CPM?

There is no single good CPM — it depends on the platform, the audience and the country. Broad display advertising often runs at a few dollars per thousand, while narrow, high-value audiences on social platforms can cost $10.00 to $30.00 or more per thousand. Judge a CPM against the same kind of audience on the same platform, and against what the impressions produce in sales or sign-ups, not against an absolute number.

How much does 100,000 impressions cost at a $4 CPM?

It costs $400.00. The maths is $4.00 × 100,000 ÷ 1,000 = $400.00. Use the “Find cost” mode in the calculator: enter a CPM of 4 and 100,000 impressions, and it shows the $400.00 total straight away.

How many impressions will $250 buy at a $5 CPM?

It buys 50,000 impressions. The maths is $250 ÷ $5.00 × 1,000 = 50,000 impressions. Use the “Find impressions” mode in the calculator: enter a cost of 250 and a CPM of 5, and it shows 50,000 impressions.

What is the difference between CPM and CPC?

CPM is the cost per 1,000 impressions — you pay every time the ad is shown, whether or not anyone clicks. CPC is the cost per click — you pay only when someone clicks the ad. A campaign can have a low CPM and a high CPC at the same time if few people click, so the two numbers measure different things. CPM is the right measure for brand awareness; CPC is the right measure when clicks are the goal.

How do I calculate CPM from cost and impressions?

Use the formula CPM = cost ÷ impressions × 1,000. For example, a $100 campaign that reaches 10,000 impressions gives $100 ÷ 10,000 × 1,000 = $10.00 CPM. Enter the cost and the impressions in the calculator’s “Find CPM” mode and it shows the answer with the maths underneath, so you can check it.

What does CPM mean in advertising?

CPM stands for cost per mille, where mille is Latin for a thousand. It is the price of showing an ad 1,000 times. A CPM of $2.00 means every 1,000 impressions cost $2.00, so a single impression costs $0.002. Advertisers quote the price per thousand rather than per impression because a single impression costs a fraction of a cent, which would be an awkward number to compare.

Is a lower CPM always better?

No. A lower CPM means cheaper attention, but not necessarily better value. A $10.00 CPM on a narrow, well-targeted audience can be better value than a $2.00 CPM on a broad audience that never buys, because the expensive impressions reach people who actually convert. Judge a CPM by what the impressions produce — sales, sign-ups or clicks — not by the number alone.

How do I work out my advertising budget from a target CPM?

Multiply the CPM by the impressions you want, then divide by 1,000: budget = CPM × impressions ÷ 1,000. For example, a $4.00 CPM for 100,000 impressions needs $4.00 × 100,000 ÷ 1,000 = $400.00. Use the calculator’s “Find cost” mode: enter the CPM and the impressions you want, and it shows the budget.

Does the CPM calculator work for any currency?

Yes. The maths — CPM = cost ÷ impressions × 1,000 — is the same in every currency, because the formula does not depend on the currency. The tool shows $ in its examples as a generic symbol; just read it as your own currency when you use it. It does not convert between currencies and it does not use live prices, so the numbers it shows are purely the result of the figures you enter.

Is the CPM calculator free?

Yes — the CPM Calculator is completely free, with no sign-in and no limits. It runs entirely in your browser, so nothing you enter is uploaded anywhere, and you can use it as often as you like, for campaigns of any size and any CPM.