Google Ads daily budget calculator
Divide the monthly budget by 30.4 to get the average daily budget to enter in Google Ads. Google can then spend up to twice that on a single day, and up to 30.4 times it across the month, which is your monthly figure.
That is €59.21 more than the monthly budget, so in a 31-day month the monthly limit is what stops the spend, not the calendar.
The formula
daily budget = monthly budget / 30.4
most in one day = daily budget * 2
most in the month = daily budget * 30.4 (= the monthly budget)A client on €3,000 a month gets a daily budget of €98.68. On a busy day Google may spend up to €197.37, and over the month it will not charge more than €3,000.
What Google says a daily budget allows
Google Ads does not have a monthly budget setting. It has an average daily budget, and it publishes two ceilings on it:
Your daily spending limit (two times your average daily budget for most campaigns) on any particular day.
Your monthly spending limit (30.4 times your average daily budget for most campaigns) in any particular month.
Source: Google Ads Help, answer 6385083, checked 3 September 2026.
Spending up to twice the daily budget on one day is the system working as documented, not a fault to escalate. The monthly limit is the protection, and it is only equal to your monthly figure when the daily budget was derived with 30.4.
Why divide by 30.4 and not by the days in the month
30.4 is 365 divided by 12, the average month. Because Google's monthly limit uses the same number, a daily budget of monthly / 30.4 makes the monthly ceiling exactly the figure you agreed with the client, in every month.
Divide by the calendar days instead and the ceiling moves. Applying Google's 30.4x to a daily budget of monthly / days in month gives:
| Days in the month | Google's monthly ceiling, as a share of your monthly figure |
|---|---|
| 28 | 108.6% |
| 29 | 104.8% |
| 30 | 101.3% |
| 31 | 98.1% |
So dividing by 28 in February lets Google spend up to 108.6 per cent of the agreed figure, and dividing by 31 caps a 31-day month below it. No single divisor both uses the full amount and caps at it in every month. 30.4 chooses the cap, which is the side of the trade an agency answers to a client for.
What this calculator does not cover
- Meta. Its daily budgets follow different rules and are not modelled here.
- A budget changed part-way through the month. For that, use the mid-month budget adjustment calculator.
- Campaigns Google treats differently. Both quotes above say “for most campaigns”, so check Google's page for the campaign type you run.
Checking it across every client
Setting the right daily budget is the start of the month. Knowing each client is still on course by the 12th is the job the budget pacing calculator does for one client, and Adswave does for all of them, across Google Ads and Meta, read-only. See budget pacing in Adswave or pricing.