Why Google Ads spent more than your daily budget

Google Ads can spend more than your daily budget because the figure you set is an average. Google Ads Help puts the daily spending limit at two times your average daily budget and the monthly limit at 30.4 times it, for most campaigns. A €50 daily budget can therefore spend up to €100 on one day and up to €1,520 in a month.

That is the documented rule, not a fault. For an agency, the day matters less than the month, because client agreements are usually monthly. Set the daily budget correctly and Google's monthly limit equals your agreement.

How much can Google Ads spend over your daily budget?

Google states both limits on one help page. Word for word:

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.

So there are two ceilings. On any single day, spend can reach twice the average daily budget. In any one month, it can reach 30.4 times it. The number 30.4 is roughly 365 divided by 12, the average number of days in a month.

The arithmetic for a €50 daily budget

most in one day    = average daily budget * 2
most in one month  = average daily budget * 30.4

At €50 a day:

most in one day    = 50 * 2    = €100
most in one month  = 50 * 30.4 = €1,520

A €100 day is inside Google's published limit. So is a €1,520 month. The question that matters is whether €1,520 is the number your client signed off.

What a 2x day means for a monthly client agreement

Say a client approves €1,500 for the month, and you turn that into a daily budget in Google Ads. The monthly limit is what protects that agreement. It only equals the agreed figure when you derive the daily budget with the same 30.4.

daily budget = monthly budget / 30.4

For a €1,500 agreement:

daily budget       = 1,500 / 30.4   = €49.34
most in one day    = 49.34 * 2      = €98.68
most in one month  = 49.34 * 30.4   = €1,499.94

The ceiling lands on the agreement. It reads €1,499.94 rather than €1,500 because the daily budget was rounded down to the cent. Always round down. A daily budget of €49.35 puts the ceiling at €1,500.24, which is 24 cents over the figure you signed.

A day of up to €98.68 can still happen with this setup. It is inside the agreement, because the month as a whole is capped at the agreed figure.

Why dividing by the days in the month moves the ceiling

The obvious setup divides by the calendar month. €1,500 over a 30-day month is €50 a day. A €50 daily budget has a monthly limit of €1,520. You have allowed €20 more than the agreement without noticing.

The gap depends on the month. Google's monthly limit stays at 30.4 times the daily budget, so a calendar-day divisor gives:

monthly ceiling = monthly budget / days in month * 30.4

For a €1,500 agreement:

days   daily budget   Google's monthly ceiling   share of €1,500
28     €53.57         €1,628.57                  108.6%
29     €51.72         €1,572.41                  104.8%
30     €50.00         €1,520.00                  101.3%
31     €48.39         €1,470.97                   98.1%

The ceilings are computed before the daily budget is rounded to the cent.

February is the row that hurts. Divide €1,500 by 28 and the monthly limit becomes €1,628.57, which is 108.6 per cent of the agreement. Every heavy day that month is inside Google's limits and outside yours. Dividing by 31 fails the other way. The ceiling drops to €1,470.97, below what the client is paying for.

Dividing by 30.4 has a trade-off of its own. At €49.34 a day, spending exactly the daily budget on each of February's 28 days totals €1,381.52. Doing the same on each of 31 days totals €1,529.54, more than the monthly limit allows. No single divisor both uses the full amount and caps at it in every month. Dividing by 30.4 chooses the cap, which is the side an agency answers to a client for. The synthetic 30.4-day month entry has the definition and the arithmetic.

What to tell a client who saw a day at double the budget

Picture a client who sees €98 spent against a €49.34 daily budget. They may assume something broke. Get ahead of it with five plain points:

• The number in Google Ads is an average daily budget, not a daily cap.
• Google publishes a limit of twice that average on any one day.
• In any one month, Google's limit is 30.4 times the average.
• We set the average so that 30.4 times it equals your monthly budget of €1,500.
• A busy day is inside your monthly figure. The month is what we report against.

Send Google's two lines with the link to its page. The rule then comes from Google, not from you. Three lines of multiplication settle the conversation faster than any reassurance.

What the two quoted limits do not tell you

The quotes are precise, and they are narrow. Four things stay open:

• Campaign type. Both lines say "for most campaigns". They do not say which campaigns differ. Check Google's page for the campaign types you run.
• Why a day ran heavy. The quotes set limits. They give no reason for any single day.
• Refunds and credits. Neither line mentions them. Read Google's page rather than a summary of it.
• A budget changed part way through the month. The quotes do not cover it. For the arithmetic of a mid-month change, the mid-month budget adjustment calculator spreads the remaining budget over the days left.

How Adswave checks the month for every client

The free Google Ads daily budget calculator does this arithmetic for one budget. Enter the monthly figure and the month length. It returns the daily budget to enter, both of Google's ceilings and what the daily budget adds up to over that month. No signup.

Adswave applies the same 30.4 to every client. You enter the agreed monthly budget for each linked ad account in the Client dialog, under Admin, Clients. It carries forward to later months until you change it. The Budget Pacing view then compares expected with actual spend over rolling windows of 2, 14, 30, 90, 180 and 365 days ending today, split between Google Ads and Meta.

expected spend = monthly budget / 30.4 * days in the window
variance %     = (actual - expected) / expected * 100

The variance is green up to 2 per cent, amber up to 5 per cent and red above that, for overspend and underspend alike. If you divided by 28 in February, a client spending that daily budget evenly shows about +8.6 per cent in the windows inside February. That is red. It is the same ratio as the 108.6 per cent ceiling that dividing by 28 gives. Today counts as a full day of expected spend while its spend is still partial. Every window therefore leans toward underspend until the day ends. The budget pacing formula post works through expected spend in more detail.

Overspend alerts do the watching between visits. A pacing rule compares actual spend over the last 1, 7, 14 or 30 complete days with the monthly budget divided by 30.4, times those days. Up means overspend. Thresholds are 5, 10, 15, 20, 25, 30, 45 or 50 per cent. With a Google Ads daily budget of the monthly figure divided by 30.4, a day at twice that budget reads +100 per cent on a 1-day rule. A 7-day rule at 10 per cent flags a week running 10 per cent or more ahead.

The limits, stated plainly. Rules are evaluated hourly on complete days ending yesterday. You hear about a heavy day after it ends, never during it. A rule fires at most once in 24 hours for the same account. Alert emails go to the organisation's owners and admins who have alert emails on. Members see alerts in the app only. Pacing and alerts are on every plan, from Basic at €19.99 a month (see pricing). Adswave never changes a budget or a campaign. It reads the spend and tells you. You make the change in Google Ads.

Questions people ask

Can Google Ads spend double my daily budget?

Yes. Google Ads Help puts the daily spending limit at two times your average daily budget, for most campaigns, on any particular day. A €50 daily budget can spend up to €100 on one day. In a month the limit is 30.4 times the daily budget, which is €1,520 at €50 a day.

Why is Google Ads spending more than my budget?

The daily budget is an average, and Google's documented daily limit is twice that average. If the monthly total looks high, check how the daily figure was set. A daily budget of the monthly figure divided by 30 puts Google's monthly ceiling at 101.3 per cent of it. Divided by 28, the ceiling is 108.6 per cent.

How do I stop Google Ads from overspending?

Set the daily budget to the monthly figure divided by 30.4, rounded down to the cent. Google's documented monthly limit then lands on the amount you agreed, or a few cents under it. Single days can still reach twice the daily budget inside that limit. To see a heavy week while there is time to act, track pace against the monthly figure. The budget pacing calculator does it by hand for one client. Adswave pacing alerts do it for every client you set a rule on.

Does Google refund overspend?

Google's two published limits, quoted in this post, are spending limits. They say nothing about refunds or credits, so this post cannot answer that from them. Read Google's page, answer 6385083, for what Google says about it. What the quotes do settle is narrower. A €100 day on a €50 daily budget is inside Google's published daily limit.

Adswave tracks Google Ads and Meta budget pacing for agencies, read-only, with alerts on every plan. Start a 7-day free trial, no card required.

Google Ads limits quoted from Google Ads Help, answer 6385083, checked 3 September 2026. Every other figure on this page is arithmetic on those two lines or a fact about Adswave.