Clicks Needed = Target Conversions / Landing Page Conversion Rate
Impressions Needed = Clicks / CTR
Budget = (Impressions / 1,000) x CPM
Daily Budget = Budget / 30
CPA = Budget / Target Conversions
This calculator works backwards: given a target number of conversions, it calculates the impressions and budget you need. It assumes your CTR and conversion rate stay constant, which they typically do until scaling or fatigue sets in.
A worked example
Target 100 conversions per month, $5 CPM, 1.2% CTR, 5% landing page conversion rate:
- Clicks needed = 100 / 0.05 = 2,000 clicks
- Impressions needed = 2,000 / 0.012 = 166,667 impressions
- Budget = (166,667 / 1,000) x 5 = $833 per month
- Daily budget to start = 833 / 30 = $28 per day
- Resulting CPA = 833 / 100 = $8.33 per conversion
If conversion rate drops to 3% (common as you scale and audience gets broader):
- Clicks needed = 100 / 0.03 = 3,333 clicks
- Impressions = 3,333 / 0.012 = 277,777
- Budget = $1,389 per month
- CPA rises to $13.89
CPM on Meta (Facebook/Instagram) varies by audience, placement and season. Estimate conservatively:
- Narrow custom audience: $1 to $3 CPM, high relevance, lower scale.
- Broad interest targeting: $3 to $8 CPM, medium relevance, higher scale.
- Lookalike or retargeting: $2 to $5 CPM, warm audience, predictable.
- Competitive or seasonal: $8 to $15 CPM, high demand, lower availability.
CTR on Meta feed placements averages 0.8% to 1.5%. Stories and Reels run 1% to 2%+. Landing page conversion rates vary by product: e-commerce 2% to 5%, SaaS free trial 8% to 15%, lead gen 5% to 20%.
How to use this to negotiate
This tool helps you plan and pressure-test:
- Set a realistic conversion rate first. Do not guess 10% if your historical landing page is 3%. Use historical data or run a small test campaign first.
- Estimate CPM and CTR conservatively. If you have not run Meta before, assume higher CPM and lower CTR than you hope for. Better to over-budget than under-deliver.
- Calculate your maximum CPA. Work backwards from your deal value and margin using the break-even or CPA calculator, then see if this budget can achieve it.
- Start with a test budget 50% lower. Run at half this daily budget for a week. If CTR and conversion match your estimate, scale up. If they differ, recalculate before committing the full budget.
Questions people ask
What if my actual CTR is different?
Recalculate with your actual CTR. If you ran a test, use that data instead of the estimate. CTR varies by creative quality, audience and placement; each ad set is different.
Why does conversion rate matter so much?
It determines how many clicks you need per conversion. A 3% rate needs 33 clicks per conversion. A 5% rate needs 20. The difference is massive at scale.
Should I start with the full daily budget immediately?
No. Start at 50% to 70%, monitor for 3 to 5 days. Once metrics (CTR, conversion rate) match your estimate, scale up. Ramping prevents learning phase issues.
What if my CPM is much higher than estimated?
It means audience is competitive or your creative is not resonating. Test new creative, narrow your audience, or pick a less competitive season. Higher CPM kills profitability quickly.
Can I achieve the target conversions at lower daily budget?
Only if you improve CTR (better creative), conversion rate (better landing page) or lower CPM (better targeting). Otherwise, lower daily spend means lower conversions, not the same conversions cheaper.
Last reviewed 11 September 2026. Formulas and benchmarks are published on the page so you can check them. This tool gives estimates, not quotes.
