General rule of thumb: 3x your target CPA (Cost Per Acquisition) per day
So if your target cost per sale is $15, aim to spend at least $45/day.
Why 3x CPA?
Because PMax needs enough daily conversions to learn — ideally 30–50 conversions per week for the algorithm to properly optimize. Anything less, and it just drifts.
Budget tiers to consider:
| Daily Budget | When to Use It |
|---|
| $20–30/day | Absolute minimum for testing, ideal if your product is low-ticket ($10–$25) |
| $40–60/day | Safer zone for getting out of learning faster, works well for products priced $25–$75 |
| $75–100+/day | Recommended if you want faster data and your product is $100+ or you have multiple SKUs to test |
Pro Tips for Small Budgets:
Use one campaign with one asset group to avoid spreading the budget too thin
Turn off Final URL Expansion to avoid wasting clicks on non-converting pages
Optimize for higher-volume actions (like add-to-cart or initiate checkout) if purchase volume is too low
Use high-intent audience signals (e.g., search terms, website visitors, converters)
