Budget Pacing Calculator: Google vs Meta
Why did a £100 budget spend £180? Both platforms call it a daily budget, and both let a day run over it. They cap the overspend differently: Google over the calendar month, Meta over a Sunday-to-Saturday week.
Checked against Google Ads Help and Meta's Business Help Centre on 19 October 2026. Every Google and badge links to its source.
1. What a daily budget allows
Google: 2x on a day, 30.4x in a calendar month, for most campaigns. Google Meta: up to 175% on a day and 7x in a Sunday-to-Saturday week; with ad set budget sharing, 210% and 8.4x. Ad set budget sharing can't be used with campaign budgets. Meta
2. Was that spend normal?
Type in what a campaign spent on one day. Uses the daily budget from section 1.
3. Changing the budget part way through
Both platforms pace the rest of the period to the new budget. Neither lets a late increase catch up on earlier underspend.
Google: mid-month change
Google's formula: spend so far + new budget × remaining calendar days, counting the day of the change. The day's limit uses the highest budget set that day. Google A campaign that starts mid-month paces to the calendar days left. Google
Meta: mid-week change
Meta's formula: new budget × days left in the week + up to 25% of the daily budget, on top of what's already spent. The day's limit is 75% over the highest budget in place that day. Meta's $100 example assumes ad set budget sharing is off. Meta
4. Fixed-total budgets
When a client needs a hard ceiling for a period, both platforms have a fixed-total option. Google's campaign total budget runs 3 to 90 days on Search, Shopping and PMax, has no 2x daily cap, and can't be added to an existing campaign. Google Meta's lifetime budget is a hard cap, not an average. Meta
Google campaign total budget: re-pacing
Google re-paces to spend what's left over the days left, and any single day can run higher because there's no daily cap. Google's own example: £800 left over 7 days is about £114 a day. Google
5. The rules side by side
| Rule | Google Ads | Meta Ads |
|---|---|---|
| Period the cap works over | Calendar month: 30.4x the average daily budget Google | Sunday-to-Saturday week: 7x the daily budget Meta |
| Most on a single day | 2x the average daily budget, for most campaigns Google | 175% of the daily budget; 210% with ad set budget sharing Meta |
| Budget changed part way through | Spend so far + new budget × calendar days left in the month, including the day of the change Google | Spend so far + new budget × days left in the week + up to 25% of the daily budget Meta |
| Several edits in one day | That day's limit is 2x the highest budget set that day Google | That day's limit is 175% of the highest budget in place that day Meta |
| Starting part way through | A new campaign paces to the calendar days left in the month Google | Daily budget × days left in the week + up to 25% of the daily budget Meta |
| Spend over the limit | You're never billed above the daily or monthly limit; Google covers the difference Google | Meta says it will consider refunds above 1.75x the daily budget on a day or 7x in a week, depending on the case Meta |
| Changing the end date | Counts as a budget change for the monthly maximum Google | Doesn't change how Meta paces the budget Meta |
| Ad scheduling | Monthly limit stays 30.4x, paced regardless of how many days are scheduled Google | A daily budget can't run an ad set scheduled for less than a day; use a lifetime budget Meta |
| Fixed-total option | Campaign total budget: 3 to 90 days, hard cap, no daily cap, new campaigns only Google | Lifetime budget: hard cap Meta |
6. Sources
- Google: About spending limits · How budget changes take effect · Budgets overview
- Meta: About daily budgets · About budgets
The calculators apply each platform's published rules to your numbers. They don't predict what a campaign will spend, only the most it can be billed. If you want to go through a budget against your own account, get in touch.