Ad Budget Calculator
Reverse-engineer monthly ad spend from a conversion goal and your acceptable CPA. Get the daily cap to enter in Google Ads.
How many conversions you want per month.
The most you can pay per conversion and still be profitable.
Buffer for testing and seasonality. 20% is a sensible default.
Result
Base 7500 × 1.20 contingency.
Set this as your campaign-level daily cap. Google can spend up to 2x on any single day.
The bottom-up budget formula
Monthly budget = monthly conversion target × acceptable CPA × (1 + contingency)
Treat the contingency as a testing fund — you’ll need to spend something on ad copy A/B tests, new audiences, and seasonal pushes. 15–30% is normal; if you’re a brand-new account or a brand-new product, push contingency to 40–50% for the first 3 months.
How to set the daily cap correctly
Google Ads will spend up to 2x your daily budget on any single day, balanced over the month. So if you enter $100/day expecting to spend $3000/mo, you’ll actually fluctuate between $50 and $200/day and end up at ~$3050. Set the daily cap to monthly budget ÷ 30.4, not the historical month-length average.
The mistake that nukes budgets
The single biggest budget killer in PPC isn’t under-budgeting — it’s under-monitoring. A negative keyword conflict, a search-term explosion in a niche, or a runaway PMax asset group can burn through 30 days of planned spend in 5 days. The free MarqOps audit won’t catch this in the moment, but the full platform’s anomaly detection will.
FAQ
How do I decide an ad budget?⌄
Start from the bottom up: pick a monthly conversion target (e.g. 50 paid customers), pick an acceptable cost per acquisition (e.g. $80, well under your CLV), multiply. That's your minimum monthly ad budget. Add 15–30% contingency for testing.
How much should I spend on ads as a percentage of revenue?⌄
Rule-of-thumb varies wildly by industry. Direct-to-consumer ecommerce often runs 15–25% of revenue on ads; SaaS marketing budgets are typically 10–20% of ARR; local services run 5–10%. These are rough — use the bottom-up math instead whenever you can.
Why does my actual spend always exceed the budget I planned?⌄
Two reasons: 1) you set a Google Ads daily budget but the system can spend up to 2x on a given day; 2) you didn't set enough negative keywords so wasted spend balloons. MarqOps daily anomaly detection catches both within 24h.
Related
Want this monitored automatically?
Inside MarqOps you set targets per brand, get alerted when actuals drift, and ship branded weekly reports to clients.
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