Transaction ID

A transaction ID in Google Ads is the unique order number sent with a purchase conversion, so Google Ads counts a repeated order only once.

By Berend Vrakking, founder of Product Metrics. Updated 13 November 2026.

Transaction ID example

Three conversions reach one Purchase conversion action
Conversion received	Value	Transaction ID	Google Ads
Thank-you page loads	€84.50	10482	Counted
Same page reloaded	€84.50	10482	Duplicate, not counted
Next order	€42.00	10483	Counted

Two carry order 10482, so Google Ads counts two orders worth €126.50, as the shop does. Illustrative data.

Put it into practice

Calculate it: POAS calculatorCompare profit and revenue on the same ad spend.
Read the guide: Stop counting refundsSend refunds and cancellations, step by step.

Transaction ID: one product and the whole account

Google Ads Help calls unique transaction IDs, such as order confirmation numbers, essential for accurate conversion measurement. When two conversions for the same conversion action carry the same ID, the second is not counted. The ID holds up to 64 characters and nothing that identifies a customer.

Deduplication works per conversion action. A browser tag and a server upload of one order only match when both send the same ID; two purchase actions that each record it are not deduplicated against each other.

The ID also lets you correct an order later, because online conversions can only be adjusted if they carry one. Full Signal Tracking sends the order ID as the transaction ID, so Google Ads counts each order once, and refunds adjust it later.

Transaction ID: common mistake

Sending the same ID for every order, which Google Ads Help says results in undercounting. In Google Tag Manager, enter the ID as a variable, not a fixed string.

Transaction ID: questions

Why does Google Ads show fewer conversions than my shop orders?

Google Ads counts only purchases that follow an ad interaction within the conversion window, 30 days for clicks unless you change it; your shop counts every order. If other channels do not explain the gap, check that the tag fires on every order and no ID is reused.

Why does Google Ads report different revenue than my webshop?

Google Ads reports a conversion on the date of the ad click, not the order date, and only for ad-attributed orders; the Conversions (by conv. time) column reports by order time. Revenue also differs when the value you send includes VAT or shipping and your shop report does not.

How do I stop Google Ads counting cancelled orders as conversions?

Send a retraction: Google Ads Help says it permanently removes the conversion and sets its value to 0.00. A restatement changes the value but not the count, for partial refunds. Both find the order by its transaction ID.

How do I check if Google Ads conversion tracking is accurate?

Place a test order and look for its ID in the conversion request, usually as the oid parameter. Google Ads does not report transaction IDs, so compare order counts with the by conv. time columns over the same dates, allowing 24 to 48 hours for processing.

Sources

Keep reading

Conversion adjustmentsRetract or restate an order by its ID.
Primary conversion actionWhich purchase action counts in Conversions.
Consent modeWhy some orders go unobserved.
Full Signal TrackingEvery order, with its ID, to Google Ads and Meta.
Shopify server-side trackingThe Shopify order ID goes to Google Ads as the transaction ID.
WooCommerce server-side trackingThe WooCommerce order ID goes to Google Ads as the transaction ID.