Account Anomaly Detector Script vs a Monitoring Tool (2026)

Updated July 2026.

The Account Anomaly Detector is a free Google Ads script, published by Google, that emails you when today's impressions, clicks, conversions, or cost deviate too far from the average of the same weekday over previous weeks. It works, and it costs nothing — within documented limits: one account, four metrics, email delivery only, and at most one alert per metric per day. This is an honest accounting of what it does, what it doesn't, and when you've outgrown it.

What the account anomaly detector script actually does

Straight from Google's documentation (last updated May 19, 2026):

1. You install the script template in your account and copy Google's template spreadsheet, where you set thresholds for the four metrics and an email address.
2. Google recommends scheduling it hourly; if that's too noisy, daily around midday.
3. On each run it compares today's stats so far against the average of the same day of week over past weeks — stats for a Tuesday at 1 PM are compared with the 26 previous Tuesdays (the lookback is adjustable).
4. Because Google Ads statistics can be up to 3 hours delayed, a 7 PM run only considers data up to 4 PM.
5. If a metric crosses its threshold, it emails you. Only one email per alert type is sent per day; the alert flag lives in the spreadsheet and clears on the first run of the next day (or when you delete the cell manually).

The spreadsheet doubles as a small dashboard: each run writes today's numbers next to the historical weekday averages, so you can eyeball how far off you are. Thresholds are set per metric as multipliers, and any metric can be switched off by setting it to “No alert.”

How to set up the anomaly detector script

1. From Google's documentation page, click Install the script template — it creates the script in your Google Ads account.
2. Click Copy the template spreadsheet to make your own copy of the alerting sheet.
3. Paste your spreadsheet's URL into the script's spreadsheet_url config value.
4. In the spreadsheet, set your email address, the lookback in weeks, and the threshold multipliers for impressions, clicks, conversions, and cost.
5. Schedule the script to run hourly, and run a preview first to confirm it can read the sheet.

Budget half an hour, and remember this is per account: ten accounts means ten scripts, ten sheets, ten schedules to keep healthy.

The documented limitations

• Single account. The official solution is titled “Single Account.” Running it across a manager account means a community-maintained MCC port on GitHub, or installing and maintaining a script-plus-spreadsheet pair in every account.
• Four metrics, account level only. Impressions, clicks, conversions, cost. No CPA, no ROAS, no CTR, and nothing at campaign level — a campaign cratering inside a stable account is invisible.
• One-directional checks. Reading the source: it alerts on impressions, clicks, or conversions too low and cost too high. Cost mysteriously halving — often a delivery or billing problem — never fires. Neither does a click surge from a bot swarm.
• Flat multipliers, not statistics. Thresholds are fixed multipliers of the weekday average. There's no variance adjustment, so volatile accounts alarm constantly and stable ones under-alert; the same multiplier can't fit both.
• Same-weekday baselines break on calendar effects. Comparing against 26 previous Tuesdays fails when a holiday, sale, or seasonal ramp makes this Tuesday legitimately different — expect false alarms every holiday week.
• Email only, once per day per metric. A 9 AM cost alert is the last you'll hear today, even if spend accelerates all afternoon.
• No cause. The email says a metric misbehaved. Whether it was a bid change, a broken landing page, or a client's edit is your afternoon to spend.

Anomaly detector script vs monitoring tool: side by side

When the free script is enough

Genuinely: one account, Google Ads only, a team that lives in email, and tolerance for the occasional holiday false alarm. Install it — ten minutes of setup beats no monitoring, and Google keeps the docs current. You'll feel the ceiling when you add accounts or platforms, when “too low vs 26 Tuesdays” cries wolf during your seasonal peak (the fix for that is real statistics — see statistical significance in paid media), or the first time an alert costs you a half-day hunting for the cause.

The Ad Spend is the version with the ceiling removed: learned baselines instead of flat multipliers (methodology in Google Ads anomaly detection), alerts in Slack with the causing change attached, and configurable alerting across five platforms. Connect via OAuth — no scripts to babysit — at The Ad Spend.

FAQ

What is the Google Ads Account Anomaly Detector script?

A free script published by Google that compares today's impressions, clicks, conversions, and cost against the average of the same weekday over previous weeks (26 in Google's example) and emails you when a threshold is crossed. Google recommends running it hourly.

Does the Account Anomaly Detector work for MCC / manager accounts?

Google's official solution is single-account. A community-maintained MCC version exists on GitHub, or you can install the script and its spreadsheet separately in each account you manage.

Why does the anomaly detector script send false alerts on holidays?

Its baseline is the average of the same weekday over past weeks. Holidays, sales, and seasonal ramps make today legitimately different from an ordinary Tuesday, so the flat-multiplier comparison misfires. Learned baselines that model variance and trend handle these cases.

What can't the script detect?

Anything outside its four account-level metrics and directions: no CPA or ROAS checks, no campaign-level anomalies, no cost-too-low or clicks-too-high alerts, and no indication of what caused the anomaly. It also alerts at most once per metric per day, by email only.