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Shopping cart conversion rate: how to measure it and why it’s important

Forms

This is a guide on how to measure your shopping cart conversion rate, and how to use this metric during the conversion rate optimisation process.

What is it?
There are a number of different ways to measure your shopping cart conversion rate, and I’ll cover all the major ways and talk about the positives and negative of each. However you measure it, and ideally you use more than one way, and understanding how well your shopping cart converts visitors in to converted customers is the starting point for optimising your checkout process. The metrics also act as a measurement as you move through the optimisation process, allowing you to see how well your changes and experiments impact this end-point in the buying process.

How do you measure it?

High Level Way 1:
Shopping Cart Conversion Rate =
(Converted Customers / Individuals who add to the shopping cart) * 100

Negatives: Metric covers too many points in the buying process, from adding to cart, to viewing cart, then all the checkout steps after that.

High Level Way 2:
Shopping Cart Conversion Rate =
(Converted Customers / Individuals who see the shopping cart page or popup) * 100

Notes: This should track just people who have chosen to see their shopping cart as part of the buying process.
Positives: Takes in to account only those who have an intent to complete the checkout process.
Negatives: This metric covers many steps after it, it’s a good way to measure at a high level but it doesn’t make it easy to understand where the particular issues are in the process.

Advanced Way – Shopping to Checkout Conversion Rate:
Start Checkout Conversion Rate =
(Individuals who see the shopping cart page or popup / Individuals who see Page 1 of the checkout process) * 100

Advanced Way – Page 1 Starter Rate:
Step 1 Visitor to Starter Conversion Rate =
(Individuals who start typing in Page 1 / Individuals who see Page 1 of the checkout process) * 100

Advanced Way – Page 1 Starter to Completion Conversion Rate:
Step 1 Starter to Completion Conversion Rate =
(Individuals who complete Page 1 / Individuals who start typing in Page 1 of the checkout process) * 100

Notes: Step 2 and Step 3 should be repeated for each page in the checkout process.
Positives: Breaks down checkout conversion rate into multiple metrics, allowing you to see where the weak points are and where you should start optimizing.

Here’s how the equations work with following sample data:

  • 100 website visitors add an item to the shopping cart
  • 70 visitors choose to start the checkout process by viewing their cart
  • 60 visitors view the first step of the checkout process
  • 50 visitors start typing in Page 1 of the checkout
  • 30 visitors complete Page 1 of the checkout process and move to Page 2
  • 2 visitors complete the checkout process
High Level Way 1:
(2 / 100) * 100 = 2%

High Level Way 2:
(2 / 70) * 100 = 2.86%

Advanced Way – Shopping to Checkout Conversion Rate:
(60 / 70) * 100 = 85.71%

Advanced Way – Page 1 Starter Rate:
(50 / 60) * 100 = 83.33%

Advanced Way – Page 1 Starter to Completion Conversion Rate:
(30 / 50) * 100 = 60%

Why is the first calculation the wrong way?

To optimise your forms it’s critical to isolate to two areas; the conversion rate between form viewer and form starter (effectively the number of people who see the form and then begin giving you information) and secondly the conversion rate from form starter to conversion.

The process of improving these two conversion rates is different, and it involves different changes. Getting more people to start filling in your form is a different challenge to getting more people to complete it, and the metric that sits between these two is form starters. I’ve seen that companies who focus on these challenges separately see greater success than those who don’t.

How do I measure Form Starters?

Tools like Google Analytics aren’t build to track forms, and they won’t tell you how many people started your form. I wrote a guide to Formisimo vs Google Analytics that explains how you can hack GA to get some basic data, but the most accurate way to understand Form Starters is to sign up for a Formisimo account. You’ll get seven days of data for free.

What’s a good Checkout Conversion Rate?

Whilst there’s some general (and sometimes very far off) average metrics for sites, it’s not worth considering what’s good (or bad) in terms of a checkout conversion rate. Every site is different, and has it’s own challenges with that long and complex process of converting a customer. Instead I’d suggest finding your benchmark and working forwards from this. That’s the most important thing to a conversion rate optimiser.