Conversion Lift Claims: How to Read Them Without Getting Fooled

1. Why most lift claims are unfalsifiable

The core problem with a claim like “increases conversions by 30 percent” is that it is usually impossible to verify or disprove. Conversion rate depends on hundreds of factors — your traffic quality, your prices, your product, your design, the season, the device mix. Attributing a specific percentage lift to one tool, across every store, ignores all of that. A number that cannot in principle be checked against your reality is not evidence; it is marketing. And a claim that could never be proven wrong tells you nothing, because it would be stated whether it were true or not.

This is not to say social proof and conversion tools do not work — many genuinely help. It is to say that a headline percentage is the wrong thing to trust. The honest truth is that any given tactic might lift your conversions a little, a lot, or not at all, depending on your specific situation. A vendor claiming a precise universal figure is either overreaching or hoping you will not think too hard about it. Once you see that, the giant percentages on landing pages lose their power, and you can evaluate tools on better grounds.

2. The tells of a fabricated number

Fabricated or misleading lift claims share recognisable tells. The first is false precision: a figure like “24.3 percent” implies a rigorous study measured to a decimal, yet no source is given. Real measured results come with context — who was studied, how many, over what period. A lone decimal with no citation is a red flag, not a credential. Genuine data is rarely that tidy, and when it is, it is proudly sourced.

The second tell is the enormous round number: “up to 300 percent.” The words “up to” are doing enormous work here — “up to 300 percent” includes zero, and one cherry-picked best-case customer justifies the headline while telling you nothing about the typical result. The third tell is the absent denominator: a lift with no baseline. “Doubled conversions” from 0.1 percent to 0.2 percent is technically true and practically trivial. When a claim gives you a percentage but no starting point, sample size, or source, treat the number as decoration.

3. What a credible claim actually looks like

Credible conversion claims look different, and once you know the shape you spot them instantly. They are hedged rather than absolute, ranged rather than pinpoint, and honest about variability. A believable phrasing is something like “can lift conversions by up to ~15 percent, depending on your store and how you use it” — note the “can,” the rounded figure, and the explicit acknowledgement that results vary. That reads as a reasonable expectation, not a guarantee, which is exactly what an honest vendor can actually stand behind.

Better still are claims backed by transparent evidence: a case study naming the store, the baseline, the timeframe, and how the result was measured — ideally with a controlled test rather than a before-and-after that could be explained by a dozen other changes. When a vendor shows you their working — sample size, method, the fact that outcomes differ — they are treating you as a thinking buyer. That transparency is itself a signal of a trustworthy tool. Reward the vendors who hedge and cite; be wary of the ones who promise a miracle to a decimal place.

4. A worked example: reading two claims side by side

Imagine two social proof tools competing for your business. Tool A’s landing page shouts “Increase your sales by 24.3% instantly!” in large type, with no source, no sample, and no baseline. Tool B says “In our own data, stores that enabled notifications saw conversion lifts that varied widely — often up to around 15 percent — though results depend heavily on your traffic and setup,” and links to a couple of named case studies with real numbers.

Which should you trust more? Tool B, clearly — even though its headline number is smaller. Tool A’s claim is the more exciting and the less believable: the false precision, the absent source, and the “instantly” all mark it as marketing rather than evidence. Tool B’s claim is modest, hedged, and supported, which is what real results look like. The lesson is counterintuitive but reliable: the bigger and more precise the promised number, the more sceptical you should be. A vendor confident enough to tell you “it depends” is usually the one with nothing to hide.

5. How to test any claim on your own store

The ultimate defence against a dubious lift claim is that you can measure the truth yourself. No vendor’s number matters as much as what a tool does on your actual site. The right way to find out is a controlled test: run the tool for a portion of your traffic and not for the rest, over a period long enough to gather meaningful data, and compare the conversion rates. That isolates the tool’s effect from everything else changing on your site.

If a clean split test is beyond your setup, a careful before-and-after can still be informative — measure a representative baseline, switch the tool on, change nothing else, and watch the same metric — but be honest that it is weaker evidence, because other factors could be moving too. Either way, the point is that you hold the real answer. Instead of arguing with a vendor’s percentage, you can generate your own. Most good tools offer a free tier or trial precisely so you can do this. Use it, and let your own data decide.

6. Where Proofly stands on this

We think the honest position is the one this whole article argues for: social proof genuinely can help, but the size of the lift depends on your store, and no vendor should pretend otherwise with a precise universal figure. So rather than promise you a specific percentage, Proofly’s recommendation is to try it and measure the effect on your own site. The tool includes analytics on how your notifications perform, and it is easy to run alongside a controlled test so you can see the real impact for yourself rather than taking a number on faith.

That is also why Proofly offers a free tier: it lets you put social proof on your site and judge the result against your own data before paying anything. If you want to evaluate the effect honestly — the way this article recommends you evaluate every conversion tool — you can start with a free Proofly account, enable notifications, and test the lift on your own store. A tool that encourages you to check its impact rather than trust its headline is one you can take seriously.

7. The takeaway

Conversion lift claims are marketing until proven otherwise. The giant precise numbers — “24.3 percent,” “up to 300 percent” — are usually unfalsifiable, unsourced, or built on a cherry-picked best case, and the more impressive they look, the more sceptical you should be. Credible claims are hedged, ranged, and cited: “can lift conversions by up to ~15 percent, depending on your store” is the shape of an honest expectation. Above all, remember that you can measure the truth yourself with a controlled test on your own site. Trust your data over any vendor’s decimal, and you will never be fooled by a conversion claim again.