Facebook Ads Budget Calculator
Work out the total Facebook Ads budget needed to hit a specific conversion target given your landing page conversion rate, expected CTR, CPM, and campaign duration. Use it before launching any paid campaign to avoid under- or over-spending.
Last updated: September 2026
Formula below · 1 source (Wikipedia) · Updated Sep 2026
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About this calculator
To generate a target number of conversions on Facebook, you work backwards through the funnel from conversions to impressions, then price those impressions using CPM. The formula is: Daily Budget = targetConversions / (conversionRate/100) / (ctr/100) × (cpm/1000) / campaignDuration. First, targetConversions / (conversionRate/100) gives the number of clicks needed. Dividing by (ctr/100) converts clicks into required impressions. Multiplying by (cpm/1000) prices those impressions, giving the total campaign budget. Dividing by the campaign length in days gives the daily budget to set in Ads Manager. The total budget depends only on the conversion target and the funnel rates; a shorter campaign needs the same total spread over fewer days, so its daily budget is higher. Every variable is under partial marketer control: improving CTR via better creative reduces required impressions; improving landing-page conversion rate reduces required clicks; better audience targeting can lower CPM.
How to use
Goal: 200 conversions. Conversion rate: 5%. Expected CTR: 2%. CPM: $10. Campaign duration: 2 Weeks (14 days). Step 1: Clicks needed = 200 / 0.05 = 4,000. Step 2: Impressions needed = 4,000 / 0.02 = 200,000. Step 3: Total budget = 200,000 × ($10/1,000) = $2,000. Step 4: Daily budget = $2,000 / 14 = $142.86. Enter these five values and the calculator returns a required daily budget of $142.86. Running the same goal over 1 Month instead would need $2,000 / 30 = $66.67 per day.
Frequently asked questions
How do I estimate my Facebook Ads CTR before launching a campaign?
If you have run Facebook campaigns before, use your historical average CTR from Ads Manager as a starting point — most advertisers see 0.5–2% for feed ads and 0.5–1% for Audience Network placements. If you are launching for the first time, industry benchmarks by vertical from WordStream suggest e-commerce averages around 0.7–1.2%, while finance and insurance can reach 0.5–0.8%. It is safer to be conservative (use a lower CTR) when budgeting so you do not underfund the campaign. After the first 3–5 days of a live campaign, replace the estimate with your actual CTR and recalculate to adjust spend.
What CPM should I use when planning a Facebook Ads budget?
CPM on Facebook varies widely by audience, placement, industry, and time of year, ranging from $5 for broad cold audiences in off-peak periods to $30+ for highly targeted retargeting audiences in Q4. Your Facebook Ads Manager will show historical CPMs if you have run ads before; otherwise, use $10–$15 as a conservative planning estimate for most B2C campaigns. CPM spikes during Black Friday, Christmas, and election periods, so add a 20–40% buffer if your campaign runs during those windows. Using a higher CPM estimate when planning ensures you have sufficient budget even if auction prices rise unexpectedly.
Why does campaign duration affect the total Facebook Ads budget needed?
The total budget is tied to how many impressions you must buy to hit your conversion goal, and those impressions cost the same whatever the time frame. Duration therefore changes how the total is spread: the calculator divides the total by the number of days to give the daily budget. A 14-day campaign needs roughly twice the daily budget of a 28-day campaign for the same conversion target, assuming CPM and rates stay constant. In practice, shorter campaigns with high daily budgets sometimes see higher effective CPMs because Facebook's algorithm has less time to find efficient delivery, so treat the calculated budget as a floor rather than a ceiling.