The commercial effect of design is read in numbers your finance team already keeps: the price customers accept without arguing, how often you win against a named competitor, how long customers stay, what it costs to win one in the first place, and how many people search for you by name. You pick the one the work is meant to move, write down what it reads today, and agree the date you will look again. A CFO who has been handed a satisfaction score and asked to treat it as a return is right to be sceptical. The market-level research is worth knowing, and it settles less than people quoting it usually claim.
What the market-level studies show
In October 2018 McKinsey published the McKinsey Design Index, built by tracking the design practices of 300 publicly listed companies over five years, against more than two million pieces of financial data. Top-quartile scorers grew revenue 32 percentage points faster than their industry counterparts over the period, and total returns to shareholders 56 percentage points faster ("The Business Value of Design", McKinsey Quarterly, 2018). The Design Management Institute put the same question to the stock market. Its 2015 Design Value Index, a portfolio of 16 listed design-centric companies assembled with Motiv Strategies, showed a 211% return over the S&P 500 across the ten years to 2015, the third consecutive year the index cleared 200%.
Both findings describe portfolios of large public companies. They tell a board that strong design capability and strong financial performance travel together at that scale. Neither one can tell you what your redesign returned. If you are being asked to fund design work on the strength of a study with Apple in the index, the number being quoted is not about your company.
Name the number before the work starts
Design work is hard to value afterwards because nobody decided what it was for beforehand. The fix belongs to how decisions are made, before any finance method is reached for. Put it in the kick-off, out loud, with whoever owns the numbers in the room: which figure is this supposed to move, in which direction, by roughly how much, and by when. Record what that figure reads on the day, and note what else is changing in the same window, because a pricing change or a new competitor will otherwise take the credit or the blame.
That conversation does a second job. A design brief that survives the question tends to be a brief the business actually wants. One that cannot name a number is usually a brief about taste, and taste arguments are the ones that stall in review for months. Flowdonia's method, Differentia, runs on the same three moves the OneBlade launch ran on: decide the direction, make it hold across everything the company does, and show it landed. The showing is built in from the start.
The number that moves first
Most commercial numbers report the past. One reports earlier. At the IPA's EffWorks Global conference on 14 October 2020, Les Binet presented share of search: a brand's share of all category search queries, taken from public search data that goes back to 2004 and can be read weekly. Across the categories he studied, cars, energy and mobile handsets, share of search moved ahead of market share, by as much as a year in cars.
That matters for design and brand work because the effect reaches the market long before it reaches the revenue line, and a finance team watching only revenue will call the work a failure while it is still working. Binet's finding is a strong correlation, so test it against your own category's history before you rely on it. At three months, it gives you something to show.
What it looks like when it lands
I led the go-to-market design for Philips OneBlade. It reached €55 million in its first year in a category that had not existed before it, and it became the fastest Philips category to €100M, both figures reported by Philips' Business Lead for Shaving and Grooming. My seat was design lead on the go-to-market accelerator, and the commercial programme had its own leads. That is the shape most of these attributions have: design moved the number alongside other things that also moved it.
The consumer philips.com redesign I led lifted NPS by 12 points. On its own that persuaded nobody. The same work carried a €4M a year effect, and that is the figure that made it a decision the business could repeat. The numbers test is the same one in shorter form: a satisfaction score counts once it connects to something finance already tracks.
A test to run this week
Take the last design decision your company made that cost real money. Write down, in one sentence, which commercial number it was supposed to move. If nobody can answer, you have found the reason the work is unmeasurable, and the problem sits in how it was commissioned.
Then ask whoever owns that number for its value on the month the work landed and its value now. Ask for the same two readings on the nearest competitor-facing figure you have, win rate or price realised.
Last, pull your share of search for the past two years alongside the two or three brands you lose deals to. It costs nothing and takes an afternoon. If the line turned up around the time the work landed, you have something to put in front of the CFO well before the revenue arrives. If it did not move at all, that is worth knowing now.
Flowdonia works with scaling companies to decide their direction, make it hold, and show it landed. The services say what that looks like in practice.