Every owner who's paid for a redesign eventually asks some version of the same question: did that actually work? Not "does it look better," which is usually obvious within a week, but did it make or save the business money.

Most of the time, the honest answer is nobody actually checked. The new site shipped, everyone moved on, and the question quietly went unanswered.

Alex Williams wrote a genuinely useful piece on Smashing Magazine walking through exactly how to build a case for a redesign, using an example of a fictional mid-size SaaS company's onboarding redesign.

Is the invoice what counts?

Where most ROI conversations go wrong is thinking the cost side only counts what got invoiced. Design hours, a developer's time, maybe a tool subscription. That's real money, but it's not the whole number.

What about the time reviewing mockups, sitting in feedback calls, going back and forth on copy? If you or a manager spent four hours a week for two months reviewing a redesign, that's a real cost too.

Correlation isn't the same as proof

Say the redesign ships and conversions go up the following month. Was the redesign the only change, or did it piggy back other changes that month which could've also positively impacted conversions such as a price adjustment, a seasonal traffic bump, or even a competitor's site going down?

Where you can, keep the old design and A/B test real traffic before converting fully. Run the old and new versions side by side for a few weeks rather than switching everyone over at once.

Where A/B testing isn't practical, measure steadily for a few weeks before the change and keep measuring after, so you have an actual baseline instead of a guess.

And if something else genuinely did happen at the same time, a promotion, a pricing change, a press mention, write that down and discount for it honestly.

Pair what moved first with what it caused

A checkout flow that got simpler and immediately saw completion rates climb is a leading indicator. Cart abandonment dropping the following weeks could be the real indicator. IOW, the simpler checkout wasn't the direct cause of higher completion rates; the decrease in abandoned carts was.

Presented together, "checkout completion went from 62% to 89%, and abandoned carts fell alongside it" is a much harder story to poke holes in than either number by itself.

The same logic applies to anything that doesn't translate cleanly into a dollar figure. Support tickets related to a confusing form, first impressions from a handful of customer interviews, a Net Promoter Score before and after.

None of it needs to be dressed up as revenue. Stated plainly next to the numbers that do translate, it does real work: "Setup went from a two-star average complaint to a non-issue, and support tickets on that flow dropped by a third" is a sentence a business owner trusts, because it's specific instead of vague.

Why this is worth doing even at small-business scale

None of this requires a data team or a formal boardroom. It requires writing down, before the work starts, what you'd actually consider a win, and checking back afterward instead of assuming the new design is working because nobody's complained.

We think about this on both sides of a redesign for the same reason. It's part of why good print and digital UI design starts with a real conversation about purpose of the design, not just how it needs to look, and it's the same discipline behind why a cheap site tends to cost more later than the number on the invoice suggests.

A redesign that can't answer "did it work?" a few months down the road is a redesign that wasn't really finished.