Jim Nielsen noticed he is visiting status pages more often — GitHub down, CI down, AI services down, Slack down — and that status pages are full of numbers like 100%, 99.72%, 99.09%, 98.98%. Those all look like grades in school. They are not.
The numbers are not wrong. They are the wrong interface:
- Percentages near 100 are nonlinear, so 99.9% and 99.99% read as neighbours while the second is ten times less downtime
- The Richter scale makes the point: a 6.2 and a 7.8 do not look far apart and are not remotely the same thing
- Infrastructure people internalise this — “two nines, three nines” — because they swim in the numbers daily
- But the audience for a status page is no longer only infra people; it is increasingly everybody, including the customers deciding whether to keep paying
Jason Gorman supplies the reliability half of the argument: 90% to 99% is as hard as getting to 90% in the first place, and 99% to 99.9% is just as hard again. Each nine costs roughly what the previous one cost, which is precisely why the percentage form hides how much is being bought.
The fix he proposes is small and concrete: put the human quantity next to the ratio.
- Instead of “GitHub Actions: 98.31% uptime”
- Say “GitHub Actions: 12 hours affected in the last 30 days (98.31% uptime)”
The general rule is worth stealing beyond status pages: meter the thing your audience already has a feel for, and treat the industry-standard unit as a parenthetical. One version requires you to internalise the nonlinear significance of numbers near 100. The other requires knowing what an hour is.