CleverQA
Free tool

Crash-Free Rate Calculator

Enter sessions and crashes and get your crash-free rate %, what that number means in practice, and a plain ship-worthy read. Runs entirely in your browser — nothing you type is sent anywhere.

99.75%
Ship-worthy

Great shape — this clears the bar most production apps ship at.

The explainer

What crash-free rate actually tells you

Crash-free rate is the share of app sessions that finished without crashing: (sessions − crashes) ÷ sessions × 100. It exists because a raw crash count is close to meaningless on its own — 500 crashes sounds bad until you learn it happened across 50 million sessions, and sounds catastrophic if it happened across 5,000. The rate normalizes for traffic so you can compare builds, releases, and platforms on equal footing.

What counts as good

We run production monitoring and crash-ingestion ourselves, so here is the honest version, not a marketing number: most teams treat 99.5%+ crash-free sessions as healthy and ship-worthy. Between 98% and 99.5% is a gray zone — plenty of shipped apps live there, but it is usually worth knowing exactly what is crashing before you roll out to everyone. Below 98% is where most teams start holding releases, because at real scale that is thousands of users hitting a crash. These are general guidelines from how the industry talks about release health (Play Vitals, Crashlytics-style dashboards) — not a certification, and a niche or early-access app may reasonably tolerate a lower number than a payments app.

Sessions vs. users — they tell different stories

Crash-free sessions answers "how often does a crash interrupt usage." Crash-free users answers "what share of my install base has hit a crash at all." The user number is almost always lower and scarier, because one unlucky user who crashes every time they open a specific screen drags the user rate down even if the vast majority of their other sessions were fine. Look at both if you can — sessions for day-to-day release health, users for how widespread the pain actually is.

Why this is the same math as a release score

Crash-free rate is one direct input into a release's overall quality score — a build with a dropping crash-free rate is a build you should not roll out further, independent of anything else looking fine. This calculator runs the exact same formula CleverQA uses when it computes that score from live Crashlytics or Sentry session data for a real release, so what you see here is not a simplified stand-in — it is the calculation, minus the automatic data feed.

Questions

What is crash-free rate?+

The share of app sessions that did NOT crash: (sessions − crashed sessions) ÷ sessions × 100. It is the standard stability metric mobile and desktop teams use to decide whether a build is healthy, because raw crash counts alone don’t tell you how many users were actually affected.

What crash-free rate counts as "good"?+

There is no single universal number, but a common bar production teams hold to is 99.5%+ crash-free sessions. 98–99.5% is where a lot of teams start gating releases and digging into what is crashing. Below 98% is generally considered unhealthy for a shipped app. These are general guidelines, not a certification — your own tolerance depends on your users and category.

Sessions or users — which should I use?+

Crash-free SESSIONS (used here) tells you how often a crash interrupts app usage. Crash-free USERS tells you what share of your install base hit a crash at all, which is usually a lower, more alarming number because one crash-prone user still counts as "affected" even with 1,000 clean sessions. Most release-health dashboards, including this calculator, lead with the sessions figure.

Is this the same math CleverQA uses internally?+

Yes — this calculator runs the identical crash-free formula CleverQA computes for a real release from Sentry/Crashlytics session data (see the release quality score). The difference is you’re typing the two numbers in by hand instead of it being pulled from a live crash feed automatically.

Want this tracked automatically, every release?

CleverQA pulls crash-free rate straight from Crashlytics or Sentry, folds it into a release quality score, and pages you when a new release drops below the bar — no manual math required.

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