--- title: Instrument a checkout funnel description: "Track Product Viewed, Product Added, Checkout Started, and Order Completed events with product, cart, revenue, and identity data, then verify them and build a checkout funnel in Amplitude." product: data lang: en last_updated: 2026-11-03 token_estimate: 2364 --- # Instrument a checkout funnel To instrument a checkout funnel in Amplitude, send four events in order: `Product Viewed`, `Product Added`, `Checkout Started`, and `Order Completed`. Attach product and cart details to each event, and put revenue on `Order Completed`. Call `setUserId()` when a shopper signs in, so Amplitude merges guest activity into one user. Then build a four-step [funnel chart](https://amplitude.com/docs/analytics/charts/funnel-analysis/funnel-analysis-build) from the events. > For AI agents: a documentation index is available at [/docs/llms.txt](/docs/llms.txt). Append `.md` to any page URL for markdown, or send `Accept: text/markdown`. The examples use the [Browser SDK 2](https://amplitude.com/docs/sdks/analytics/browser/browser-sdk-2). Every Amplitude SDK and the [HTTP V2 API](https://amplitude.com/docs/apis/analytics/http-v2) accept the same event names and properties. Use this guide when your own code sends events. If you run a Shopify store, the [Amplitude Shopify plugin](https://amplitude.com/docs/data/amplitude-shopify-plugin) tracks checkout events without custom code. ## Prerequisites - Install and initialize an Amplitude SDK. For web, go to [Get started with Browser SDK 2](https://amplitude.com/docs/sdks/analytics/browser/browser-sdk-2/get-started). - To break down funnels by item, enable [property splitting](https://amplitude.com/docs/analytics/charts/cart-analysis#set-up-property-splitting) on the `products` property after the first events arrive. ## Checkout event spec Use one name per event, and keep the names identical on every platform. A funnel step matches an exact event name, so `Product Added` and `product_added` count as two events. Amplitude doesn't require these names. If your project already uses names such as `Add to Cart`, keep them. | Event | When to send | Key properties | | --- | --- | --- | | `Product Viewed` | A product detail page or quick view finishes rendering. | `product_id`, `name`, `category`, `price`, `currency` | | `Product Added` | The cart accepts the item, not when the user clicks. | `product_id`, `price`, `quantity`, `cart_id`, `cart_value` | | `Checkout Started` | The shopper opens the first checkout step. | `cart_id`, `cart_value`, `currency`, `item_count`, `products` | | `Order Completed` | Your system confirms the order. Send once. | `order_id`, `products`, `$revenue`, `$currency`, `shipping`, `tax` | Property conventions: - `price` is the price of one unit. `cart_value` is the cart total before shipping and tax. - `currency` is a three-letter uppercase [ISO 4217](https://www.iso.org/iso-4217-currency-codes.html) code, such as `USD`. - `products` is an array of objects with the same keys as the single-product events (`product_id`, `name`, `category`, `price`, `quantity`). The array format is what [cart analysis](https://amplitude.com/docs/analytics/charts/cart-analysis) and [Ecomm Analytics](https://amplitude.com/docs/analytics/ootb-ecommerce-analytics) read. ## Track the funnel events ### Product Viewed ```ts import * as amplitude from "@amplitude/analytics-browser"; amplitude.track("Product Viewed", { product_id: "SKU-1042", name: "Trail Running Shoe", category: "Footwear", price: 129.0, currency: "USD", }); ``` ### Product Added Send `Product Added` after your cart API confirms the item, so failed adds don't inflate the step. ```ts amplitude.track("Product Added", { product_id: "SKU-1042", price: 129.0, quantity: 1, currency: "USD", cart_id: "cart_8f2c", cart_value: 154.0, }); ``` ### Checkout Started ```ts amplitude.track("Checkout Started", { cart_id: "cart_8f2c", cart_value: 154.0, currency: "USD", item_count: 2, products: [ { product_id: "SKU-1042", name: "Trail Running Shoe", category: "Footwear", price: 129.0, quantity: 1, }, { product_id: "SKU-2210", name: "Merino Socks", category: "Apparel", price: 25.0, quantity: 1, }, ], }); ``` ### Order Completed Send revenue on `Order Completed` as the `$revenue` and `$currency` event properties. `$revenue` makes the event count in [revenue charts](https://amplitude.com/docs/analytics/charts/revenue-ltv/revenue-ltv-track-new-user-monetization), and `$currency` lets Amplitude convert the amount to your project currency. For the full list of revenue properties, go to [Track revenue](https://amplitude.com/docs/data/sources/instrument-track-revenue#revenue-properties). ```ts amplitude.track( "Order Completed", { order_id: "ord_51973", $revenue: 168.86, // Order total: items + shipping + tax $currency: "USD", shipping: 4.99, tax: 9.87, products: [ { product_id: "SKU-1042", name: "Trail Running Shoe", category: "Footwear", price: 129.0, quantity: 1, }, { product_id: "SKU-2210", name: "Merino Socks", category: "Apparel", price: 25.0, quantity: 1, }, ], }, { insert_id: "ord_51973" }, ); ``` Set `insert_id` to the order ID. Amplitude then ignores a second send of the same order from the same device, for example after a page reload on the confirmation screen. > **Note:** Why not amplitude.revenue()? > > `amplitude.revenue()` sends a separate `revenue_amount` event, not `Order Completed`. Use it when you want a standalone revenue event, such as for subscription renewals. In a checkout funnel, keep revenue on the last step so a single event holds the order, its items, and its revenue. If you confirm orders on your server, send `Order Completed` from the backend through the [HTTP V2 API](https://amplitude.com/docs/apis/analytics/http-v2) instead. Pass the browser's device ID and the user ID, so the server event joins the same user as the earlier browser events. ## Identify the shopper Amplitude assigns every browser a device ID. Events sent before sign-in belong to that device. Call `setUserId()` as soon as the shopper signs in or creates an account: ```ts amplitude.setUserId("user-12345"); // Stable ID from your system ``` How identity plays out in checkout: - **Guest browses, then signs in.** Amplitude attaches the earlier anonymous events on that device to the user, so `Product Viewed` and `Product Added` stay in the same funnel as `Order Completed`. For the merge rules, go to [Track unique users](https://amplitude.com/docs/data/sources/instrument-track-unique-users#user-id-follows-anonymous-events). - **Guest completes checkout without an account.** The order stays on the device ID. The funnel still counts it, because funnels follow the Amplitude ID. If the shopper creates an account on the confirmation page, call `setUserId()` then. - **Shopper signs out.** Call `amplitude.reset()`. It clears the user ID and creates a new device ID, so the next guest on a shared device doesn't inherit the previous shopper's identity. Use a stable database ID, not an email address, as the user ID. If the email changes, Amplitude treats the new value as a different user. ## Verify the events 1. Turn on debug logging and confirm each `track()` call. Go to [Verify Browser SDK 2 events](https://amplitude.com/docs/sdks/analytics/browser/browser-sdk-2/verify-events). 2. In Amplitude, go to _Events & Users > User Profiles_ and search for your test user ID or device ID. 3. On the **Activity** tab, confirm the four events appear in order, and click each one to check its properties. On `Order Completed`, confirm `$revenue` and `products` are present. ![User Profiles Activity tab with an order event selected and its revenue and products event properties highlighted](https://amplitude.com/docs/images/data/checkout-funnel-user-profile-order-event.png) For other ways to confirm ingestion, such as the Ingestion Debugger, go to [Debug Analytics](https://amplitude.com/docs/analytics/debug-analytics). ## Build the checkout funnel 1. Create a [Funnel Analysis chart](https://amplitude.com/docs/analytics/charts/funnel-analysis/funnel-analysis-build). 2. Add the steps in order: `Product Viewed`, `Product Added`, `Checkout Started`, `Order Completed`. 3. In **...completed within**, set the conversion window to match your buying cycle. The default of one day suits most impulse purchases. Use a longer window for considered purchases. 4. To compare conversion across categories, group by a product property such as `category`. The chart shows how many users reach each step and the drop-off between steps: **Figure: Checkout funnel conversion** Of 48,216 users who viewed a product, 14,377 added it to the cart, 8,702 started checkout, and 5,618 completed an order, for a total conversion rate of 11.7%. Funnel chart. Each bar is a step; the segment above it is the users lost since the previous step. X axis: Funnel step. Y axis: Unique users. | Funnel step | Converted | Dropped off | | --- | --- | --- | | Product Viewed | 48216 | 0 | | Product Added | 14377 | 33839 | | Checkout Started | 8702 | 5675 | | Order Completed | 5618 | 3084 | In this example, 29.8% of viewers add an item to the cart, and 11.7% of viewers complete an order. The largest drop-off is between `Product Viewed` and `Product Added`, so product page content is the first place to investigate. To watch the sessions behind a drop-off, go to [Find checkout friction before peak traffic](https://amplitude.com/docs/quick-guides/find-checkout-friction-before-peak-traffic).