Free tool
Error budget calculator
Turn an SLO into a concrete error budget — then see how much of it you've already spent.
Total error budget
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Budget used
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Know your budget before you blow it
Spectra measures real uptime from multiple regions and alerts you as your error budget burns — not after it's gone. Free forever, no credit card.
Frequently Asked Questions
Answers to common questions teams ask us
What is an error budget?
An error budget is the amount of unreliability an SLO permits. If your SLO is 99.9% over 30 days, your error budget is the remaining 0.1% — about 43 minutes of allowed downtime. Spend it on risk; run out and you freeze risky changes until reliability recovers.
How do I calculate an error budget?
Error budget = (1 − SLO) × the length of the SLO window. For 99.9% over 30 days: 0.001 × 43,200 minutes ≈ 43 minutes. Enter your actual measured uptime to see how much of that budget you've already spent.
What happens when the error budget is exhausted?
A common policy is to halt feature releases and redirect effort to reliability work until you're back within budget. The budget turns the "ship fast vs. stay stable" debate into a data-driven rule.
