Why it happens
The tag sends a different part of the order. Your Shopify order total is what the buyer paid, with tax and shipping. A tag can send that total, the subtotal, or the items without tax and shipping. Each choice is valid, but each gives a different sum. In a store with EU prices that include VAT, the difference between total and net value is large enough to look like an error.
The conversion action uses one fixed value. Google Ads lets a conversion action give every conversion the same value, which Google calls a static value, or a value per transaction. If the action is set to the same value for each conversion, each order counts at that fixed number, whatever the buyer paid. Google's help also says a conversion set up with a URL can only use static values.
The currency is missing or wrong. Google says that when a tag sends no currency code, or not a 3-letter ISO 4217 code, it ignores the tag's currency and uses the currency of the action's default value. A store selling in euro with an action set to US dollars then reports euro amounts as dollars. Values in other currencies are converted to your account currency at the average daily exchange rate, so a multi-currency store never matches Shopify to the cent.
Google Ads dates value by the click. Google Ads reports a conversion on the date and time of the ad click that led to it, not the day of the purchase. A sale on Monday from a click on Friday is in Friday's value. Shopify books it on Monday. Week to week, the two drift apart, most of all around sales and holidays.
Attribution splits the credit. With data-driven attribution, Google Ads can give one conversion to several clicks in parts, such as 0.33 or 0.50. The value is split the same way across campaigns, so a single campaign's value rarely adds up to the orders it touched.
The same order counts twice. If two tags send the purchase, the value doubles with the count. See Google Ads shows more purchases than Shopify.
Refunds stay in. Shopify lowers your net sales when you refund an order. Google Ads keeps the value it received unless you adjust it. Google's help describes two adjustments: restate the value, or retract the conversion.
Only part of your sales came from Google. Shopify counts every sale. Google Ads counts value only for conversions it ties to its own ads within the conversion window. A gap in value can simply mean the rest came from e-mail, Meta or search without a click.
Check it yourself
- 1In Google Ads, open Goals > Conversions, click your purchase action and look at Value. It should say to use different values for each conversion. If it gives the same value to each one, that explains the gap.
- 2On the same page, check the currency of the default value and compare it with your store's currency.
- 3Place a test order with a known total, tax and shipping. In Google Tag Assistant, or in the network request of the conversion, read the value and currency sent. Compare it with the total, the subtotal and the net value of that order.
- 4In Campaigns, add the column Conv. value (by conv. time). It dates value by the purchase, not the click, which is closer to how Shopify reports.
- 5Compare one full week, not single days, and the same time zone in both accounts.
- 6Count your purchase actions set as Primary. More than one can double the value.
- 7Note your refunds for the same days in Shopify. If they are large, the gap may be refunds that Google Ads never heard about.
For value differences inside Meta and GA4 caused by currency, see multi-currency purchase value in Meta and GA4.
FAQ
Which value should I send to Google Ads?
Pick one and keep it. Many stores send the value without tax and shipping, because that is closer to what the sale earns. What matters for bidding is that the value means the same thing on each order.
Why is the value in Google Ads in a different currency?
Google converts conversion values into your account currency for reports. If your store and your account use different currencies, small differences come from the daily exchange rate.
Can I fix values for orders already counted?
Google Ads offers conversion adjustments: you upload a new value, or retract the conversion. Google's help says adjustments made within 7 days are read by automated bidding, and gives a longer limit for reports.
Do discounts change the value?
A discount lowers what the buyer paid. If your tag sends the price before the discount, Google Ads shows more value than Shopify.
Why do my campaign values not add up to the account total?
With data-driven attribution, one conversion can be split across campaigns in parts. Each part carries part of the value.