Conversion rate optimisation (CRO) is the practice of raising the share of visitors who complete an action you value, such as a purchase, an enquiry or a booking, by finding what stops them and testing changes that remove it. It works on the traffic you already have, so every point it adds lowers what each customer costs you in ads and content. This guide explains how to calculate conversion rate, where visitors drop out, how to run tests without upsetting Google Search, and which tools do which job.
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Originally published 19 February 2024 in the Conversions section of aemorph.com. Updated October 2026.
What Is Conversion Rate Optimisation?
Conversion rate optimisation is a repeating cycle: measure where visitors leave, form a hypothesis about why, test a change, and keep only the changes that lift the conversion rate. A conversion is any visitor action you have decided is valuable to the business. The cycle starts with research and data, not with a list of design tricks, because a change that lifts sales on one site does nothing on another.
What counts as a conversion?
A conversion is the action a page exists to produce: a sale on a product page, a submitted form on a service page, a booking on a clinic page or a call from a mobile ad. Google Analytics calls the events you mark as important "key events". Since Google unified its terms, a "conversion" is an important action you use to measure ad campaigns and steer bidding, and you create one in Google Analytics from a key event so both platforms share it (Analytics Help, Conversions vs key events).
| Conversion | Example | Type | Where you measure it | What it tells you |
|---|---|---|---|---|
| Purchase | An order completed in the checkout | Primary | Ecommerce platform and a Google Analytics key event | Revenue from the visit |
| Enquiry form | A quote request on a service page | Primary | Form submission marked as a key event | A sales lead |
| Booking | An appointment booked online | Primary | Booking confirmation page | A committed customer |
| Phone call | A tap on a phone number from a mobile ad | Primary | Call tracking in Google Ads | A lead that skipped the form |
| Account or trial sign-up | A free account created | Secondary | Sign-up event | Interest worth following up |
| Newsletter sign-up | An email address left in a footer form | Secondary | Form submission event | Permission to stay in touch |
Common conversions and where each one is measured.
Source: Google Analytics Help, October 2026
How Do You Calculate Conversion Rate?
Conversion rate is the number of conversions divided by the number of visits, sessions or ad interactions in the same period, multiplied by 100. Google Ads uses ad interactions as the base: 50 conversions from 1,000 interactions is a 5% conversion rate (Google Ads Help, Conversion rate). Google Analytics reports session key event rate, the percentage of sessions in which any key event was triggered, and user key event rate, the percentage of users who triggered one (Google Analytics, API dimensions and metrics). A session with two purchases counts once, so key events divided by sessions gives a different number; name the key event each report tracks and keep one definition.
Conversion rate = (conversions ÷ visits, sessions or interactions) × 100
| Base | Formula | Example | Best for | Where you read it |
|---|---|---|---|---|
| Ad interactions | Conversions ÷ clicks or other ad interactions × 100 | 50 ÷ 1,000 = 5% | Comparing ads, keywords and campaigns in Google Ads | Google Ads campaign reports |
| Sessions | Sessions with the chosen key event ÷ all sessions × 100 | 120 ÷ 6,000 = 2% | Tracking a whole website over time | Session key event rate in Google Analytics |
| Users | Converting users ÷ all users × 100 | 90 ÷ 4,500 = 2% | Counting how many people convert, however often they visit | Google Analytics reports |
| Page visitors | Conversions on a page ÷ visitors to that page × 100 | 15 ÷ 100 = 15% | Testing one landing page or form | A page report or your testing tool |
Pick one base for each report and keep it, because changing the base changes the rate.
Source: Google Ads Help, October 2026
What is a good conversion rate?
A good conversion rate is one that beats your own baseline for the same page, traffic source and device, because published averages mix industries, price points and definitions of a conversion. The earlier version of this page quoted an average conversion rate of 2.9% across 14 industries from Ruler Analytics' pooled research. It is withdrawn because an older average across mixed industries, built on its own sample and its own definition of a conversion, sets no target for your page. Record your current rate for each important page over at least a full month, then judge every change against that number.
Where Do Visitors Drop Out Before Converting?
Visitors drop out where a page asks for more money, effort or trust than they are ready to give, and online shops lose the most at checkout. Baymard Institute's average of 50 studies puts the documented online cart abandonment rate at 70.22% (Baymard Institute, Cart abandonment rate statistics). Part of that loss is unavoidable: 42% of the US shoppers in Baymard's 2026 survey had left a cart because they were only browsing.
| Reason for abandoning a purchase at checkout | Share of US online shoppers | Fix to test | Objection type | Page to change |
|---|---|---|---|---|
| Extra costs too high (shipping, tax, fees) | 40% | Show delivery and fees on the product page, before checkout | Cost | Product page |
| Delivery too slow | 20% | State delivery times on product and cart pages | Delivery | Product and cart pages |
| Did not trust the site with card details | 19% | Show recognised payment options and security cues beside the payment form | Trust | Payment step |
| Had to create an account | 18% | Offer guest checkout | Effort | Checkout start |
| Checkout too long or complicated | 17% | Remove every field you do not use | Effort | Whole checkout |
| Website had errors or crashed | 17% | Test the checkout on each major browser and device | Reliability | Whole checkout |
| Returns policy not satisfactory | 13% | Link a clear returns policy from the cart | Policy | Cart |
| Total cost not visible upfront | 12% | Show a running total, delivery included, from the cart onward | Cost | Cart and checkout |
| Not enough payment methods | 9% | Add the payment methods your customers already use | Payment | Payment step |
Reasons US shoppers gave for abandoning an online purchase in the previous three months (Baymard Institute, 2026 survey of 1,083 adults; more than one answer allowed). The last three columns are Aemorph's.
Source: Baymard Institute, 2026
How short does a checkout need to be?
Baymard's checkout testing finds that an ideal checkout flow needs only 12 to 14 form elements, while the average US checkout shows 23.48 by default. Baymard also estimates that the average large ecommerce site gains a 35.26% increase in conversion rate from fixing the checkout usability issues it has documented. Count the fields in your own checkout, remove every one you do not use, and test the shorter version against the current one.
How do you find the leaks on your own site?
Combine numbers that show where visitors leave with observation that shows why they leave.
- Funnel reports. Funnel and path reports in your analytics tool show the step where most visitors leave, from landing page to confirmation.
- Heatmaps and scroll maps. They show which parts of a page visitors click, ignore or never reach.
- Session recordings. Recorded visits show hesitation, repeated clicks and form errors that totals hide.
- On-page surveys and customer interviews. Asking visitors what stopped them names the objection in their own words.
- Usability tests. A few people attempting a real task on your site expose the steps that confuse them.
- Form analytics. Field-level data shows the question that makes people give up.
How Do You Run an A/B Test?
An A/B test sends part of your traffic to a changed version of a page and compares the conversion rates of the two versions over the same period, so the change, not the season, explains any difference. A multivariate test changes several elements at once and needs far more traffic to reach a reliable answer.
- Write a hypothesis. State the change, the reason and the expected effect, for example "showing delivery costs on the product page reduces checkout abandonment".
- Choose one primary metric. Pick the conversion the change targets, and fix the sample size and test length before launch.
- Split the traffic. Send visitors at random to the original or the variation, and keep each visitor in one version.
- Run whole weeks. Weekday and weekend visitors behave differently, so a test that stops mid-week compares unlike traffic.
- Read the result once. Stop at the planned sample size, not when the numbers first look good, then keep or discard the change.
- Record every test. A log of winners and losers stops the same idea being tested twice.
Does A/B testing affect SEO?
A/B testing has little effect on Google Search when you follow Google's rules: no cloaking, a rel="canonical" link from each variation URL to the original, 302 redirects instead of 301s, and tests that end as soon as they have an answer. Google states that small content variations generally do not significantly affect search performance, and that a test left running far longer than necessary risks being treated as deceptive (Google Search Central, A/B testing best practices).
How do you test landing pages for paid search?
Google Ads experiments split traffic or budget between your original campaign and a trial campaign, which makes them the cleanest way to test a new landing page against the old one for paid visitors. Google lists landing pages among the settings custom experiments for Search and Display campaigns typically test, beside Smart Bidding, keyword match types, audiences and ad groups; when the trial wins, you apply its settings to the original campaign (Google Ads Help, About the Experiments page).
Sources: Google Search Central, October 2026 and others
Which CRO Techniques Lift Conversion Rates?
The techniques that lift conversion rates each remove one objection: unclear value, hidden cost, missing trust, too much effort or a slow page.
| Technique | Objection it removes | Where to use it | What to test | Metric that shows the effect |
|---|---|---|---|---|
| Clear headline and offer | "Is this what I need?" | Homepage and landing pages | A headline that names the buyer's problem against one that names the product | Click-through to the next page |
| Specific calls to action | "What do I do next?" | Every page with a conversion | Button text that states the outcome; placement above the fold on mobile | Call-to-action click rate |
| Price and delivery shown early | "What does this really cost?" | Product pages and cart | Total cost shown before checkout against cost revealed at checkout | Cart-to-checkout rate |
| Reviews, case studies and guarantees | "Do other buyers trust them?" | Product, service and checkout pages | Proof placed beside the call to action | Conversion rate on the page |
| Shorter forms | "This is too much work" | Forms and checkout | Fewer fields; guest checkout | Form completion rate |
| Site search | "Where is the thing I want?" | Shops and large sites | Search box position; results for misspellings and synonyms | Searches that end in a product view |
| Faster, mobile-friendly pages | "This is slow on my phone" | Every page | A lighter main image and fewer blocking scripts | Mobile conversion rate |
| Personalisation | "This is not for me" | Returning visitors and regional pages | Content matched to location or earlier visits | Conversion rate of the targeted group |
Which objection each technique answers, and the first test to run.
How do calls to action convert better?
A call to action converts better when it says what happens next, sits where the visitor finishes reading, and is the only primary action on the page. "Get my quote" tells a visitor more than "Submit". The earlier version of this page recommended scarcity tactics to create urgency. Urgency belongs only where it is true: invented stock levels, countdown timers that reset and fees revealed late in checkout mislead buyers. Consumer regulators act on false urgency and late fees: the Australian guide covers the ACCC's Viagogo case and the 2027 unfair trading law, and the Singapore guide covers the Guidelines on Price Transparency.
Does page speed affect conversions and rankings?
Page speed and mobile layout shape conversions and search visibility together, because Google's core ranking systems look to reward content that provides a good page experience. Google's own checklist asks whether a page has good Core Web Vitals, is served securely, displays well on mobile devices, avoids intrusive interstitials and keeps the main content easy to tell apart, and Google evaluates these aspects page by page (Google Search Central, Understanding page experience). The earlier version of this page claimed CRO itself raises rankings; conversion rate appears nowhere in Google's page experience guidance, so the shared ground is the experience of the page, not the rate. Aemorph's guide to mobile SEO covers mobile-first indexing and the checks a phone layout needs.
When does personalisation help?
Personalisation shows different content to different visitors by location, device, traffic source or earlier visits, and it earns its place only when a test shows the personalised version beats the generic one. Start with the simple cases: a regional page for each country you sell in, and an ad that lands on a page using the ad's own words.
Which Pages Come First in CRO?
Start with the pages closest to revenue that carry the most traffic: checkout and enquiry forms first, then landing pages for paid traffic, then product and service pages, then the homepage and the blog.
| Page | Its job | First things to test | Metric to watch | Priority |
|---|---|---|---|---|
| Checkout and forms | Complete the purchase or enquiry | Field count, guest checkout, total cost shown early | Form completion rate | 1 |
| Paid search landing page | Turn a paid click into a lead or sale | Message match with the ad, one call to action, mobile load speed | Conversion rate per click | 2 |
| Product or service page | Answer the buying questions | Price, delivery, proof, a clear next step | Add-to-cart or enquiry rate | 3 |
| Homepage | Send visitors to the right page | Headline, navigation, the main call to action | Click-through to key pages | 4 |
| Blog and guides | Turn readers into leads | An offer relevant to the article, next-step links | Clicks to service pages | 5 |
Where to start, in order of closeness to revenue.
What makes a paid search landing page convert?
A paid search landing page converts when it repeats the promise in the ad, answers the searcher's question without detours and asks for one action. Google's Quality Score for Search campaigns includes landing page experience, which Google describes as how relevant and useful your landing page is to people who click your ad (Google Ads Help, About Quality Score). Aemorph builds dedicated landing pages for the ad campaigns it runs and audits them for conversion rate, user experience and message match, because a strong ad sent to a weak page wastes the click.
Which CRO Tools Do You Need?
A working CRO toolkit covers four jobs: analytics for the numbers, heatmaps and recordings for behaviour, an A/B testing platform for experiments, and your ad platform's own experiments for paid traffic. Google Optimize, the free testing tool many older guides still recommend, closed on 30 September 2023; Google now points Google Analytics users to its testing integrations with AB Tasty, Optimizely and VWO (Analytics Help, Google Optimize sunset).
| Tool type | What it shows | Examples | Use it to | Stage of the CRO cycle |
|---|---|---|---|---|
| Web analytics | Traffic, key events and funnel drop-off | Google Analytics | Find the step where visitors leave | Measure |
| Heatmaps and session recordings | Clicks, scrolling and recorded visits | Hotjar, Crazy Egg | See why visitors leave | Diagnose |
| A/B testing platform | Results of controlled experiments | AB Tasty, Optimizely, VWO | Prove which version converts better | Test |
| Product analytics | Interactions captured automatically | Heap | Answer behaviour questions without new tracking code | Diagnose |
| Ad platform experiments | Original campaign against a trial campaign | Google Ads experiments | Test landing pages and bidding for paid traffic | Test paid traffic |
Tool types, with the tools named in the earlier version of this page and Google's own testing integrations.
Sources: Google Analytics Help, October 2026 and others
The conversion optimisation tools comparison sets seven platforms side by side, with what each one does best.
Turn More of Your Visitors Into Customers
Conversion rate optimisation pays off when it follows a fixed order: measure a baseline, find the step where visitors leave, test one change against it, and keep only what wins. Fix hidden costs and long forms before testing button colours, test paid landing pages with Google Ads experiments, and keep every test within Google's rules for search. If paid search is where you need more conversions, Aemorph's SEM service builds your landing page and your Google Ads campaigns, then runs them for your first month with no management fee while you fund the ad spend. The what is digital marketing guide shows where CRO sits beside the other channels, and the SEO service brings in the organic visitors these pages convert.