How to Calculate Conversion Rate: Formula, Examples, Pitfalls

To calculate conversion rate, divide the number of conversions by the number of visits and multiply the result by 100. If your shop has 3,000 sessions and 60 orders in a month, its conversion rate is 2 percent. The formula is simple. The hard part is deciding exactly what you count: which visits, which conversions, and whether your tracking records both numbers correctly in the first place.

What is conversion rate?

A conversion is an action that matters for your business. In an online shop, this is usually a purchase. For a tradesperson, it is an enquiry via the contact form, and for a B2B service provider, it might be an appointment booking or a call. The conversion rate describes the proportion of visits or visitors that perform this action.

The conversion rate is popular because it makes channels, pages, and time periods comparable. It tells you if a new landing page works better than the old one, if visitors from Google Ads buy more often than those from Meta, and if a change in the checkout process is worth it. However, it tells you nothing about the value of a conversion. Ten enquiries for small repairs are different from ten enquiries for a new build.

How to calculate conversion rate: formula and examples

The conversion rate formula is: conversion rate (%) = conversions ÷ visits × 100. Both the numerator and the denominator must come from the same period, the same channel and the same system. If you divide orders from your shop system by sessions from Google Analytics, you are comparing two measurements with different gaps.

Online shop example: in September, a small natural cosmetics shop had 4,500 sessions and 90 purchases. 90 divided by 4,500 is 0.02, and 0.02 times 100 is 2 percent. Enquiry example: a tradesperson’s business had 1,200 sessions and 18 submitted contact forms. 18 divided by 1,200 is 0.015, or 1.5 percent. Add 12 tracked clicks on the phone number and the rate for all contact channels rises to 2.5 percent.

Calculate the conversion rate for individual parts of your offer too. A rate for the entire website mixes blog readers, existing customers, and new prospects. Often, the rate per channel, per landing page, or per campaign is more informative.

A worked example shows why this matters. The natural cosmetics shop above has 1,500 sessions from Google Ads with 45 purchases and 3,000 sessions from other channels with 45 purchases. Across all channels, that is 2 percent. Broken down, Google Ads is at 3 percent and the other channels at 1.5 percent. Only this breakdown shows where more budget pays off and where visitors are being lost. Wherever possible, calculate with whole weeks or months, because individual days fluctuate a lot and small numbers quickly lead to wrong conclusions. With only a few conversions a month, a single order changes the rate noticeably.

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Sessions or users: which base does GA4 use?

Google Analytics 4 (GA4) has called conversions ‘key events’ since 2024. Its reports offer two matching metrics: session key event rate and user key event rate. Session key event rate shows the share of sessions that contain at least one key event. User key event rate shows the share of users who triggered a key event at least once.

The session rate is usually lower, because people often visit several times before they buy or get in touch. Neither option is wrong. Pick one and stick to it, especially when you report figures to clients or management. Also bear in mind that GA4 recognises users who are not logged in on your site by a cookie in their browser. Someone who browses on a phone and buys on a laptop can therefore count as two users.

Why is there no universally good conversion rate?

People ask about a good conversion rate all the time, and plenty of industry benchmarks circulate online. These figures are of little use to you. They come from different sources, measure different things and do not say whether sessions or users are the base. A shop selling cheap consumables has completely different rates from a kitchen retailer, even if both are doing well.

A comparison with your own figures is more useful. How has your rate developed over the last few months? Which channel is well below your site average? Which landing page loses visitors who are actually a good fit? A good conversion rate is one that is measured consistently, can be traced back and improves as a result of your changes.

• The price of the offer and how much explanation it needs
• Origin of visitors, e.g. paid search, social networks, or newsletter
• What counts as a conversion: purchase, enquiry, call, download
• Proportion of returning customers
• Device, as mobile and desktop often convert differently

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How incorrect tracking distorts the conversion rate

A conversion rate is only as good as the two numbers it is based on. An error in either of them shifts the result without being obvious at first glance. The most common causes are duplicate events, wrongly configured triggers and a cookie banner that does not work properly with the tracking.

Duplicate events happen when a purchase is sent twice, for example by the shop plugin and again by Google Tag Manager, or when the order confirmation page counts again on reload. The rate then looks better than it is. A trigger on the click of the submit button also counts forms that were never sent because of an error. Without consent, GA4 does not count some visits, and depending on the setup some conversions are missing too. If visits are under-recorded more heavily than conversions, the rate appears to rise.

• Rate jumps up for no reason: check for duplicate events
• More purchases in GA4 than in the shop system: confirmation page counts multiple times
• Many enquiries in GA4, few in the inbox: trigger is on the click
• Rate drops sharply after banner change: check Consent Mode and tags

How to check your conversion rate in practice

Take a fixed period, such as the last four weeks, and compare the conversions in GA4 with the real source: orders in the shop system, enquiries in your inbox or in the CRM. Small differences are normal, because not every visitor gives consent. Large differences in either direction point to an error. Then use Google Tag Manager’s preview mode to check how often the event fires during a real test run.

An agency with several client accounts should run this comparison regularly for every client, especially after a relaunch or a new cookie banner. A B2B service provider with only a few enquiries a month can even check them one by one.

How do you get reliable numbers for the conversion rate?

A conversion rate you can trust needs clean tracking. So check the measurement first and the rate second. Trackum’s free check opens your site three times in a real browser and shows the findings with a fixed price to fix them, no sign-up needed. If nothing is set up yet, Trackum sets up Google Tag Manager, Google Analytics 4 and Consent Mode v2 with up to 15 events for €150, tested with and without consent and live within one working day. All prices plus VAT.