The currency and value parameters
Across GA4 monetary events — purchase, add_to_cart, refund, and others — two parameters carry the money: value, a number, and currency, an ISO 4217 code. GA4 requires currency whenever value is set so the figure is interpretable. This page explains the pairing rule, how mixed currencies are handled in reports, and why an unlabeled value cannot be aggregated correctly.
The pairing rule
GA4 monetary events expect value as a number and currency as a three-letter ISO 4217 code (such as USD, EUR, JPY). The documented rule is that currency is required whenever value is provided, because a bare number has no unit.
This applies consistently across purchase, add_to_cart, refund, begin_checkout, and the other value-bearing events.
Mixed currencies and aggregation
When events arrive in different currencies, GA4 can convert them for combined revenue reporting using its conversion handling, but only because each event declared its currency. Omit currency and the value becomes ambiguous — it may be ignored or mis-aggregated. Always send the pair together, and use the smallest consistent unit your platform documents.
- value: numeric amount
- currency: ISO 4217 three-letter code
- currency required whenever value is set
How it appears in analytics and logs
A value sent without currency cannot be reliably aggregated; GA4 needs the ISO 4217 code to interpret and convert the amount.
Diagnostic use case
Apply GA4's value-plus-currency rule correctly across monetary events so revenue figures are interpretable and comparable.
What WebmasterID can help detect
WebmasterID treats monetary parameters as labeled amounts so revenue stays interpretable in first-party reporting.
Common mistakes
- Sending value without currency.
- Using non-ISO currency strings.
- Mixing units (cents vs whole) across events.
Privacy and accuracy notes
value and currency describe a transaction amount, not a person. They are not payment-instrument data. Educational, not legal advice.
Related pages
- The purchase event and e-commerce
The purchase event records a completed transaction and anchors all e-commerce reporting: revenue, items, and conversion value. It carries a transaction id, a value and currency, and an items array describing what was bought. The discipline is to record the order, not the customer — product and revenue data belong in the event, personal identity does not.
- The refund event
refund is a GA4 recommended e-commerce event that records a refund against a prior transaction. It references the original transaction_id and carries the refunded value (and items, for partial refunds). It matters because reported revenue is misleading if refunds are not subtracted — refund events let analytics reflect net revenue rather than gross.
- Event parameters: adding context safely
Event parameters are the key-value details attached to an event: which button, which product, which step. They are what turns a bare event name into something analysable. The craft is choosing a small, stable set of parameters with consistent names and values — and the discipline is keeping every one of them free of personal data, because parameters are stored and widely visible in tooling.
- Event tracking docs
Send monetary parameters correctly.
Sources and verification notes
Last reviewed 2026-06-24. Facts are checked against primary/official sources where available; uncertain specifics are marked “Data not yet verified” rather than guessed.