Funnel Drop-off Calculator

Understanding the funnel drop-off calculator — concept and principle

A conversion funnel follows people through the steps that lead to a goal, such as visiting a site, viewing a product, adding it to the cart, starting checkout and completing a purchase. At every step some people leave. This calculator shows the overall conversion from the first step to the last and the share of people lost between each pair of steps, so you can see where the biggest leak is and where improvements will pay off most.

How it is calculated

• Overall conversion = step 5 ÷ step 1 × 100
• Drop from step n to n+1 = (1 − step n+1 ÷ step n) × 100

Each input is a count of people (or sessions) who reached that step in the same period. Counts should not increase from one step to the next; if they do, the data mixes different sources or periods.

The principle

The share who continue at each step is the step conversion rate, 1 − drop-off. Because each step works only on the people who survived the previous one, the overall conversion is the product of all step conversion rates. This multiplication is why a funnel is so sensitive: improving any single step by 10% lifts the final result by 10%, and a weak step caps everything after it. It also explains why the largest percentage drop is not always the best place to start; the step with the most people lost in absolute numbers, or the cheapest one to fix, can matter more.

Worked example

1. Inputs: 10,000 visitors, 4,500 product views, 900 add to cart, 450 checkouts, 270 purchases.
2. Drop 1 → 2 = 1 − 4,500 ÷ 10,000 = 55%.
3. Drop 2 → 3 = 1 − 900 ÷ 4,500 = 80%.
4. Drop 3 → 4 = 1 − 450 ÷ 900 = 50%.
5. Drop 4 → 5 = 1 − 270 ÷ 450 = 40%.
6. Overall conversion = 270 ÷ 10,000 = 2.7%, equal to 0.45 × 0.20 × 0.50 × 0.60.

How to read the result

Compare each step with your own history and with similar businesses rather than with a universal target, because conversion depends heavily on traffic quality, price and product type. In the example the product page to cart step loses 80% of viewers, the largest relative leak, and it also loses the most people (3,600). That makes it the first candidate for testing better product information, pricing clarity or a more visible cart button.

Common mistakes

• Mixing sessions and unique users across steps, which distorts every ratio.
• Comparing steps measured over different date ranges.
• Ignoring users who skip a step, such as buying directly without a product page.
• Optimising a step with high drop-off but very low volume.

Frequently asked questions

What is a good overall conversion rate?

It varies widely by industry, device and traffic source. A trend in your own data over time is a more reliable benchmark than a single industry figure.

Is drop-off the same as bounce rate?

No. Bounce rate counts single-page visits; drop-off measures how many people fail to reach the next defined step.

Can I use more or fewer than five steps?

The same formulas apply to any number of steps. Combine or leave out steps as needed, keeping the order.

Sources: Google Analytics Help, Funnel exploration