CPC (cost per click) charges you each time someone clicks. CPM (cost per 1,000 impressions) charges you for being shown, click or not. Neither is universally cheaper — which one wins comes down to your click-through rate. A high CTR makes CPM cheaper per click; a low CTR makes paying per click the safer buy.
Choose by goal first: pay per click when you want traffic, pay per impression when you want reach. Then let your CTR settle which is actually cheaper.
What each one actually means
CPC — cost per click. You're charged only when someone clicks your ad, so your spend maps directly to traffic. It's the natural choice for performance goals, and it shifts the risk of a weak ad onto the platform — no click, no charge. (Detail on the CPC calculator.)
CPM — cost per mille. You pay for every 1,000 impressions, whether or not anyone clicks. It's the natural choice for awareness and reach, and it's usually cheaper per impression — the trade is that you carry the risk of a low CTR. (Detail on the CPM calculator.)
CPC vs CPM at a glance
| CPC | CPM | |
|---|---|---|
| You pay for | Each click | Each 1,000 impressions |
| Charged when | Someone clicks | The ad is shown |
| Best goal | Traffic, conversions | Reach, awareness |
| Who carries the risk | The platform (no click, no charge) | The advertiser (pay regardless) |
| Rewards | Paying only for results | A high CTR — more clicks per paid impression |
CTR is the bridge between them
CPC and CPM aren't really separate prices — they're two views of the same auction, linked by your click-through rate:
CPC = CPM ÷ (1,000 × CTR)
This is the whole comparison in one line. Any CPM buy has an effective CPC once you know how often those impressions get clicked. The higher your CTR, the more clicks each paid thousand impressions delivers — so the cheaper CPM becomes on a per-click basis. Estimate your CTR, convert the CPM to an effective CPC, and compare it to what you'd pay per click directly.
A worked example
Say the going rate is a $10 CPM, and you could instead bid $0.40 per click. Which is cheaper?
- At a 2% CTR: effective CPC = $10 ÷ (1,000 × 0.02) = $0.50. Paying per click ($0.40) is cheaper.
- At a 3% CTR: effective CPC = $10 ÷ (1,000 × 0.03) = $0.33. Now CPM is cheaper per click.
The break-even sits at a 2.5% CTR ($0.40 effective CPC). Above it, buy on CPM; below it, buy on CPC. Same ad, same rates — your CTR decides. This is why proven, high-CTR creative is often run on CPM, while unproven campaigns start on CPC to cap the downside.
When to use each
- Choose CPC when you want traffic or conversions, your CTR is unproven or low, or you simply want to pay only for results and let the platform carry the risk of a weak ad.
- Choose CPM when you want reach or awareness, or when you have a strong, proven CTR that makes each thousand impressions cheap per click — then you capture the upside of paying a flat impression rate.
Whichever you pick, judge it on what the clicks are worth: read the cost alongside return on ad spend, not on the sticker price alone.
Where each shows up (by platform & objective)
Most platforms nudge you toward one basis or the other depending on what you're trying to do:
- Google Search — CPC-native. You bid on clicks for high-intent queries, so cost per click is the natural currency.
- Display, YouTube & programmatic (automated, auction-based ad buying) — CPM-native. These are reach and awareness placements sold per thousand impressions; you're paying to be seen. On YouTube specifically, the money you spend here is the money a creator earns a share of — our creator-side CPM calculator shows that half.
- Meta, TikTok & most social — both. The platform optimises delivery and bills on impressions under the hood, but you pick a click or awareness objective, and it effectively behaves like CPC or CPM to match.
You'll also meet hybrids — CPV for video, CPA and target-ROAS bidding for conversions — but they all resolve back to the same question: how much does a click, view or action actually cost, and is it worth it? Whichever basis a platform bills on, convert it to an effective cost-per-outcome before you compare.
Compare your click cost
Work out your cost per click — then use your CPM and CTR to find the effective CPC of an impression buy and see which wins:
CPC Calculator
Cost per click — solve for any value.
Total amount spent.
Total clicks.
Enter Cost and Clicks to see the result.
For the other side of the equation, see the CPM calculator and the CTR calculator — the three together let you compare any CPC and CPM buy directly.
Frequently asked questions
- Is CPC or CPM cheaper?
- It depends entirely on your click-through rate. CPC and CPM are linked by CPC = CPM ÷ (1,000 × CTR), so a high CTR makes CPM cheaper per click, while a low CTR makes CPC the safer buy. There's no universal winner — work out the effective CPC of a CPM buy and compare.
- When should I use CPM instead of CPC?
- Use CPM when your goal is reach or awareness and you're paying to be seen, or when you have a strong, proven CTR that makes impressions cheap per click. Use CPC when you want traffic and want to pay only for clicks, especially if your CTR is unproven or low.
- What is CPC vs CPM bidding?
- They're two ways to be charged for the same ad. CPC (cost-per-click) bidding charges you only when someone clicks; CPM (cost-per-mille) bidding charges per 1,000 impressions whether or not anyone clicks. You pick the basis that matches your objective — clicks or exposure.
- Does CPM include clicks?
- No. CPM is purely the cost of 1,000 impressions — being shown. Whether those impressions turn into clicks depends on your CTR, and that's exactly what determines whether a CPM buy is cheaper or dearer than paying per click.
Key takeaways
- CPC charges per click; CPM charges per 1,000 impressions — pick by goal (traffic vs reach) first.
- Which is cheaper depends on CTR: CPC = CPM ÷ (1,000 × CTR).
- A high CTR makes CPM cheaper per click; a low or unproven CTR favours CPC.
- Convert any CPM buy to an effective CPC and compare like-for-like.
- Use the CPC, CPM and CTR calculators together to decide.