Understanding CRO metrics isn’t about memorising formulas. It’s about knowing what each metric actually tells you, how they relate to each other, and which numbers matter most when performance changes.
If you’re unfamiliar with CRO terminology, our CRO Glossary: 20+ Terms Every Marketer Should Know covers the definitions. This guide builds on that foundation by explaining how key CRO metrics are calculated, when to use them, and how to interpret them in practice.
Some metrics use sessions, others use visitors. That distinction matters, so each formula below reflects how these metrics are typically reported in analytics tools.
CRO Metrics at a Glance
The table below summarises the key CRO metrics covered in this guide, grouped by how they’re typically used in practice.
| Metric |
Formula |
Description |
|
PrimaryNorth Star Metrics |
| Conversion Rate (CR) |
(Total Orders / Total Sessions) * 100 |
The percentage of visitors who complete a purchase |
| Revenue per Visitor (RPV) |
Total Revenue / Total Visitors |
The average value of each visit; combines CR and AOV |
| Customer Lifetime Value (LTV) |
Avg Order Value * Purchase Frequency * Lifespan |
Total revenue expected from a customer over their lifetime |
| Gross Margin |
((Revenue - COGS) / Revenue) * 100 |
The percentage of total sales revenue that the company retains |
|
SecondarySupporting Metrics |
| Average Order Value (AOV) |
Total Revenue / Total Orders |
The average amount spent by a customer per transaction |
| Purchase Frequency |
Total Orders / Total Unique Customers |
How often an average customer buys within a specific period |
| Subscription Orders per Visitor |
Total Subscription Orders / Total Visitors |
Frequency of recurring revenue generated per visitor. |
| Subscription Revenue per Visitor |
Total Subscription Revenue / Total Visitors |
Financial value of the subscription model per site visitor. |
| Repeat Purchase Rate |
Returning Customers / Total Customers |
The percentage of customers who have made more than one purchase |
| Subscription Rate |
(Subscription Signups / Total Visitors) * 100 |
Percentage of users opting for recurring billing models |
| Items per Order |
Total Units Sold / Total Orders |
Average number of products in a single transaction. |
| Avg Product Revenue / Unit |
Total Product Revenue / Total Units Sold |
The average selling price realized per unit sold. |
|
MicroDiagnostic Metrics |
| Product Detail View Rate |
(Users who viewed PDP / Total Visitors) * 100 |
Measures interest in specific products. |
| Product Listing Clickthrough Rate (CTR) |
(Clicks on Products / Total List Page Views) * 100 |
Effectiveness of category pages in driving users to products |
| Add-to-Cart (ATC) Rate |
(Sessions with ATC / Total Sessions) * 100 |
Intent to buy; measures product and price appeal. |
| Checkout - Begin Rate |
(Sessions reaching Checkout / Total Sessions) * 100 |
The transition from shopping to the buying phase |
| Checkout Completion Rate |
(Total Orders / Sessions reaching Checkout) * 100 |
Efficiency of the final payment/shipping steps. |
| Search Usage Rate |
(Sessions using Search / Total Sessions) * 100 |
Measures how proactive users are in finding products |
| Search Conversion Rate |
(Orders from Search / Sessions using Search) * 100 |
Effectiveness of site-search results in driving sales. |
| No-Result Search Rate |
(Searches with 0 results / Total Searches) * 100 |
Identifies gaps in inventory or search synonyms. |
Conversion Rate (CR)
What it measures
Conversion rate shows the percentage of sessions that result in an order. It is one of the most widely used CRO metrics, but also one of the easiest to misinterpret.
Formula
Conversion Rate (CR) = (Total Orders / Total Sessions) * 100
When it matters most
Landing pages and campaign traffic
On pages designed for a single action, conversion rate helps assess intent alignment. A low CR here often points to a messaging mismatch, unclear value propositions, or poor page hierarchy rather than traffic quality alone.
Product detail pages (PDPs)
On PDPs, conversion rate reflects how well the page answers buying questions. Pricing clarity, delivery information, imagery, trust signals, and social proof all play a role.
Checkout optimisation
In checkout, conversion rate helps surface friction introduced by form complexity, payment options, or unexpected costs. Even small improvements here can materially affect revenue.
Paid media efficiency
For paid traffic, CR provides an early signal of landing page relevance. While ROAS and CPA remain critical, CR often highlights misalignment faster.
Common mistakes
- Optimising conversion rate without considering AOV or revenue
- Comparing conversion rates across pages with different intent
- Treating small movements as meaningful without enough data
Key takeaway
A drop in conversion rate is a signal to investigate, not an automatic trigger for redesign or discounting.
Conversion Rate: What to Check First
| If conversion rate… |
Check this first |
| Drops sitewide |
Traffic mix changes, seasonality |
| Drops on PDPs only |
Add-to-Cart Rate, PDP messaging, trust |
| Drops in checkout |
Checkout Completion Rate, payment friction |
| Drops on mobile |
Mobile UX, page speed |
| Increases but revenue doesn’t |
AOV and Revenue per Visitor |
| Fluctuates week to week |
Sample size, traffic volatility |
Average Order Value (AOV)
What it measures
Average Order Value shows how much customers spend per order. AOV optimisation often delivers faster revenue impact than conversion rate changes, particularly for established stores.
Formula
Average Order Value (AOV) = Total Revenue / Total Orders
When it matters most
Upsell and cross-sell optimisation
AOV is most relevant when testing complementary products or recommendations. Helpful, well-timed upsells can increase order value without harming conversion.
Bundling and pricing strategies
Bundles, tiered pricing, and volume discounts rely on AOV to validate whether perceived value outweighs added complexity.
Cart and checkout experiments
Free-shipping thresholds and last-step add-ons can lift AOV when implemented with restraint and clarity.
Common mistakes
- Increasing AOV at the expense of conversion rate
- Adding friction through aggressive upsells
- Ignoring the impact on repeat purchases
Key takeaway
AOV optimisation should support the buying decision, not complicate it.
Average Order Value: What to Check First
Use the checklist below to understand what may be driving AOV changes before making adjustments.
| If AOV… |
Check this first |
| Drops sitewide |
Pricing changes, promotions ending |
| Increases but CR falls |
Upsell placement, bundle friction |
| Increases but revenue is flat |
Overall conversion rate |
| Changes mostly on mobile |
Cart layout, interaction cost |
| Improves but repeat rate drops |
Bundle size, product suitability |
Revenue per Visitor (RPV)
Revenue per Visitor shows the average revenue generated by each unique visitor. It combines conversion rate and AOV into a single commercial metric.
Formula
Revenue per Visitor (RPV) = Total Revenue / Total Visitors
When it matters most
Evaluating test performance
RPV is one of the most reliable CRO test metrics. When CR and AOV move in opposite directions, RPV clarifies whether the outcome actually improves revenue.
Comparing variants with trade-offs
Some experiments produce mixed results. RPV allows objective comparison between variants with different behavioural outcomes.
Assessing traffic quality
Stable or improving RPV alongside fewer sessions often signals higher-quality traffic rather than a performance issue.
Common mistakes
- Ignoring RPV when CR and AOV move in opposite directions
- Celebrating CR gains that don’t increase revenue
Key takeaway
RPV is often the clearest indicator of whether optimisation is driving revenue.
Revenue per Visitor: What to Check First
| If RPV… |
Check this first |
| Drops sitewide |
CR and AOV together |
| Drops while CR improves |
AOV impact from discounts |
| Improves with fewer visitors |
Traffic quality |
| Fluctuates after tests |
Variant trade-offs, sample size |
| Improves but profit declines |
Discount depth, margins |
Gross Margin
What it measures
Gross margin shows the percentage of revenue you keep after subtracting the cost of goods sold (COGS).
It adds a profitability lens to CRO, so you can avoid optimising for “more revenue” when the real outcome is lower profit.
Formula
((Revenue - COGS) / Revenue) * 100
When it matters most
- Discounting and promotion strategy
- Bundling, free gifts, and “Buy More” offers
- Shipping thresholds and free delivery experiments
- Subscription offers where margin varies by product mix
Common mistakes
- Celebrating AOV or RPV improvements that come from margin-eroding discounts
- Ignoring fulfilment and packaging costs when using COGS as a proxy for margin
- Optimising upsells that increase revenue but lower profit due to product mix
Key takeaway
Use gross margin alongside CR, AOV and RPV so you optimise for profitable growth, not vanity gains.
Customer Lifetime Value (LTV)
What it measures
Customer Lifetime Value estimates the total revenue a customer generates over their relationship with your brand. For CRO, LTV helps prioritise which behaviours and journeys are worth optimising, not just first-purchase conversion.
Formula
Customer Lifetime Value (LTV) = Avg Order Value * Purchase Frequency * Lifespan
Understanding the components of LTV
Purchase Frequency
Measures how often an average customer buys within a specific frequency.
Purchase Frequency = Total Orders / Total Unique Customers
Average Customer Lifespan
Lifespan represents how long customers continue purchasing from your brand. This is difficult to calculate precisely without dedicated analytics or retention tools. Many teams use fixed time windows (for example, 6 or 12 months) to track trends directionally.
When it matters most
- Subscription and replenishment brands
- Retention-focused optimisation
- Aligning acquisition with long-term profitability
Common mistakes
- Treating LTV as a retention-only metric
- Optimising short-term conversion at the expense of long-term value
Key takeaway
LTV does not need to be perfectly calculated to guide better CRO decisions.
Customer Lifetime Value: What to Check First
| If LTV… |
Check this first |
| Declines over time |
Repeat Purchase Rate |
| Improves without higher AOV |
Purchase Frequency |
| Drops after promotions |
Discount depth, expectations |
| Varies by channel |
Traffic intent and quality |
| Feels unclear |
Time window consistency |
Supporting CRO & Revenue Metrics
These metrics support your core CRO metrics by explaining how revenue is generated, not just whether users convert.
Subscription Orders per Visitor
What it measures
The frequency of subscription purchases generated per visitor.
Formula
Total Subscription Orders / Total Visitors
This metric helps quantify how effectively your site converts visitors into recurring revenue.
Subscription Revenue per Visitor
What it measures
The average subscription revenue generated per site visitor.
Formula
Total Subscription Revenue / Total Visitors
This is especially useful for subscription and replenishment brands where long-term value outweighs one-off purchases.
Subscription Rate
What it measures
The percentage of visitors who sign up for a subscription.
Formula
(Subscription Signups / Total Visitors) * 100
Subscription rate helps assess how compelling your subscription offer is relative to one-time purchase options.
Repeat Purchase Rate
What it measures
The percentage of customers who return to make more than one purchase.
Formula
Returning Customers / Total Customers
This metric is a key indicator of retention, product satisfaction, and long-term revenue stability.
Items per Order
What it measures
The average number of products included in a single transaction.
Formula
Total Units Sold / Total Orders
Items per order helps explain changes in AOV and highlights opportunities for bundling and cross-sell optimisation.
Average Product Revenue per Unit
What it measures
The average revenue generated per unit sold.
Formula
Total Product Revenue / Total Units Sold
This metric helps separate pricing effects from volume-driven revenue changes.
Supporting & Diagnostic CRO Metrics
These metrics help explain why core metrics move by identifying friction and intent signals inside the conversion funnel.
Product Detail View Rate
What it measures
Measures interest in specific products.
Formula
(Users who viewed PDP / Total Visitors) * 100
Product Listing Clickthrough Rate (CTR)
What it measures
Measures the effectiveness of category pages in driving users to product detail pages.
Formula
(Clicks on Products / Total List Page Views) * 100
Add-to-Cart (ATC) Rate
What it measures
Measures intent to buy and reflects product appeal, pricing clarity, and perceived value.
Formula
(Sessions with Add to Cart / Total Sessions) * 100
Checkout Begin Rate
What it measures
Measures the transition from shopping to the buying phase.
Formula
(Sessions reaching Checkout / Total Sessions) * 100
Checkout Completion Rate
What it measures
Measures the efficiency of the final payment and/or shipping steps.
Formula
(Total Orders / Sessions reaching Checkout) * 100
Search Usage Rate
What it measures
Measures how frequently visitors use on-site search to find products.
Formula
(Sessions using Search / Total Sessions) * 100
Search Conversion Rate
What it measures
Measures how effectively search results drive completed purchases.
Formula
(Orders from Search / Sessions using Search) * 100
No-Result Search Rate
What it measures
Measures how often users receive no results when using site search.
Formula
(Searches with no results / Total Searches) * 100
Acquisition & Commercial Efficiency Metrics
These metrics help connect CRO performance to acquisition efficiency and paid media outcomes.
Customer Acquisition Cost (CAC)
What it measures
The average cost to acquire a new customer.
Formula
Total Marketing Spend / New Customers Acquired
While CAC is not a CRO metric on its own, CRO improvements directly reduce CAC by improving conversion efficiency.
Cost per Order (CPA)
What it measures
The marketing cost required to generate a single transaction.
Formula
Total Marketing Spend / Total Orders
CPA is closely linked to conversion rate and is often used to evaluate campaign-level performance.
ROAS – Return on Advertising Spend
What it measures
The revenue generated for every unit of advertising spend.
Formula
Revenue from Ads / Cost of Ads
ROAS improves when CRO increases revenue without increasing traffic or media costs.
Technical & Post-Purchase Metrics That Influence Conversion
These metrics don’t directly measure conversion intent, but they strongly influence trust, usability, and customer satisfaction.
Page Load Time
What it measures
The average time it takes for a page to load.
Formula
Total Load Time / Total Page Loads
Slow page load times increase bounce rates and reduce conversion potential, particularly on mobile.
Payment Success Rate
What it measures
The percentage of successful payments compared to total payment attempts.
Formula
(Successful Payments / Total Payment Attempts) * 100
This metric highlights technical or provider-related issues that may be blocking completed purchases.
Refund and Return Rate
What it measures
The percentage of orders that result in refunds or returns.
Formula
(Total Returns / Total Orders) * 100
High return rates can signal mismatched expectations, poor product information, or quality issues.
Understanding CRO metrics is less about tracking everything and more about knowing what to look at when something changes.
If you want a quick sense check of how your store compares and where your biggest opportunities might be, our CRO Benchmarks tool gives you personalised insights and A/B test ideas based on your key metrics.
For a broader view of how Shopify and eCommerce benchmarks shift by industry, device, and funnel stage, our eCommerce Benchmarks Guide breaks t his down in more detail.
And if you ever want help turning these metrics into a clear, prioritised optimisation roadmap, that's where a CRO Audit can help. No redesign assumptions. And most importantly, no guesswork. Just clarity on what to test next.
