Estimate what a Facebook and Instagram ads budget will get you: impressions, people reached, clicks, sales or leads and return on ad spend. Or switch modes to work out the budget you need for a sales goal.
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How to use it
- Choose whether to estimate results from a budget, or the budget needed for a number of sales or leads.
- Enter your CPM (cost per 1,000 impressions), click-through rate and the conversion rate on your website. Take them from Ads Manager and GA4 for past campaigns if you have them.
- Enter your average frequency, the number of times each person sees the ad, to estimate reach.
- Add your average order value to see revenue and return on ad spend (ROAS).
How it’s worked out
The calculator follows the path from ad to sale:
- Impressions = budget ÷ CPM × 1,000
- People reached = impressions ÷ frequency
- Link clicks = impressions × click-through rate
- Sales or leads = clicks × conversion rate
- Cost per click = CPM ÷ 1,000 ÷ click-through rate
- Cost per sale or lead = cost per click ÷ conversion rate
- ROAS = sales × average order value ÷ budget
To find the budget for a goal, it works backwards: budget = sales wanted × cost per sale.
Worked example: the default figures
| Step | Calculation | Result |
|---|---|---|
| Budget | $500 | |
| Impressions | $500 ÷ $10 CPM × 1,000 | 50,000 |
| People reached | 50,000 ÷ frequency of 2 | 25,000 |
| Link clicks | 50,000 × 1.2% | 600 |
| Sales | 600 × 2.5% | 15 |
| Cost per click | $10 ÷ 1,000 ÷ 1.2% | $0.83 |
| Cost per sale | $0.83 ÷ 2.5% | $33.33 |
| Revenue at $45 a sale | 15 × $45 | $675 |
| ROAS | $675 ÷ $500 | 1.35× |
A 1.35× ROAS means $1.35 back for every $1 of ads, before product and delivery costs. For most shops that loses money: check your own break-even point with the break-even ROAS calculator. To get 50 sales at $33.33 each, the same funnel would need a budget of about $1,667.
Worked example: a UK shop
A shop spends £1,000 with a £7 CPM, a 1% click-through rate, a 3% conversion rate, a frequency of 2.5 and a £60 average order.
- Impressions: about 142,857, reaching about 57,143 people
- Link clicks: about 1,429, at £0.70 each
- Sales: about 43, at £23.33 each
- Revenue: about £2,571, a ROAS of 2.57×
What changes the cost of Facebook ads
Meta sells ads through an auction. It doesn’t simply pick the highest bid: each ad gets a total value based on the advertiser’s bid, the estimated action rate (how likely this person is to take the action you’re optimising for) and ad quality. A more relevant ad can win at a lower cost. In practice, your costs depend on:
- Audience and country: competitive audiences and wealthier markets usually cost more per impression.
- Time of year: CPMs tend to rise in busy retail periods such as November and December, when more advertisers compete.
- Ad quality: ads people hide or report cost more to deliver; ads people engage with cost less.
- Optimisation goal: optimising for purchases usually costs more per impression than optimising for clicks, but brings better-qualified people.
Which number to improve
Each rate multiplies through the whole funnel, so a small improvement anywhere has a big effect. Using the default figures:
| Change | Sales from $500 | Cost per sale |
|---|---|---|
| None | 15 | $33.33 |
| CPM falls to $8 | 18.75 | $26.67 |
| Click-through rate rises to 1.5% | 18.75 | $26.67 |
| Conversion rate rises to 3.5% | 21 | $23.81 |
Better creative tends to lift click-through rate; a faster, clearer landing page lifts conversion rate. Both are usually easier to control than CPM. Check that the text fits before you launch with the Meta ads text preview, and plan monthly spend with the ad budget planner.
Where to find your numbers
- CPM, CTR and frequency: Ads Manager shows these columns for every campaign. Use link click-through rate rather than all clicks, which include likes and profile taps.
- Conversion rate: in GA4, divide purchases or leads by sessions from Facebook and Instagram, or use the conversion rate calculator.
- New advertisers: run a small test for a week or two, then come back with real figures. Averages from other businesses vary too much to plan with.
Frequently asked questions
How much do Facebook ads cost?
There is no fixed price. You set a budget and pay through an auction, so cost per click and per sale depend on your audience, country, season and how relevant your ad is.
What is CPM?
Cost per mille: what you pay for 1,000 impressions. A $10 CPM means $10 for every 1,000 times your ad is shown.
How do I work out cost per sale?
Divide your CPM by 1,000, then by your click-through rate and your conversion rate. With a $10 CPM, 1.2% CTR and 2.5% conversion rate, that’s $33.33.
Why is my reach lower than impressions?
Because people see your ad more than once. Reach is roughly impressions divided by frequency.
What is a good ROAS for Facebook ads?
Anything above your break-even ROAS, which depends on your profit margin. A shop with a 40% margin breaks even at 2.5×.
Does the highest bid always win?
No. Meta combines the bid with how likely the person is to act and the ad’s quality, so a relevant ad can win at a lower cost.
Is anything stored?
No. The calculator runs in your browser, so your figures aren’t sent anywhere.
Sources
- Meta Business Help Centre: About ad auctions
- Instagram Help Centre: How Instagram ads use machine learning
- Google Ads Help: Conversion rate
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