SLO error-budget and burn-rate calculator

About this tool

Give it an SLO target and a window, from an hour to 90 days, and it shows the error budget, the downtime that budget allows, how fast the current error rate is burning it, and when the budget runs out. The URL holds your inputs, so you can paste the result into a review.

Good for

• Turning '99.9% over 30 days' into minutes people can feel
• Deciding whether today's error rate is an incident or just spending
• Setting burn-rate thresholds for alerts

Not for

• Alerting itself: it calculates one window at a time, while production alerting wants multiple windows and burn rates evaluated continuously
• Picking the target: that's a conversation with the people who own the product

Further reading on mikepreston.org

• SLOs Without the Theatre: Error Budgets That Survive Contact With Management
• SLOs, SLIs, and Error Budgets
• Retries Should Have a Budget—Not Just a Backoff