Error Budget Burn Rate Calculator

About the Error Budget Burn Rate Calculator

The error budget burn rate measures how quickly your service is consuming its allowed error budget. A burn rate of 1.0 means you're consuming the budget at exactly the expected pace — you'll exhaust it precisely at the end of the SLO window. A burn rate above 1.0 means you're consuming faster than sustainable, and below 1.0 means you have budget to spare.

This calculator takes your SLO, the total budget period, the elapsed time, and the budget consumed so far to compute the current burn rate and projected time to exhaustion. It also suggests multi-window alert thresholds following Google's recommended burn-rate alerting strategy.

Burn rate alerting is the gold standard for SLO-based monitoring. Rather than alerting on raw error rates (which cause alert fatigue), burn rate alerts fire only when the consumption trajectory threatens to exhaust the budget before the window resets. This gives SRE teams timely, actionable signals without excessive noise.

When This Page Helps

Raw error rate alerts are noisy and don't account for budget context. A brief spike may look alarming but barely dent the monthly budget. Burn rate alerts connect incidents to their actual SLO impact, ensuring on-call engineers respond to meaningful threats. This calculator helps you configure those thresholds correctly.

How to Use the Inputs

1. Enter your SLO percentage (e.g., 99.9).
2. Enter the total SLO window period in days (e.g., 30).
3. Enter the number of days elapsed in the current window.
4. Enter the budget consumed so far in minutes.
5. Review the burn rate and projected time to exhaustion.
6. Use the suggested alert thresholds for multi-window alerting.

Example Calculation

Tips & Best Practices

• A burn rate of 1.0 means exactly on pace; above 1.0 is unsustainable.
• Use multi-window alerts: fast burn (14.4x over 1h) and slow burn (1x over 3d).
• Google recommends alerting at burn rates of 14.4, 6, 3, and 1.
• Reset burn rate tracking at the start of each SLO window.
• Combine burn rate with remaining-budget alerts for comprehensive coverage.
• Investigate any sustained burn rate above 1.5 even before alerts fire.

Understanding Burn Rate

Burn rate is a normalized measure of error budget consumption speed. It answers the question: at this pace, when will we run out of budget? A burn rate of 1.0 over the full window means you'll exactly deplete the budget. Any sustained rate above 1.0 means the budget will be exhausted early.

Multi-Window Alert Strategy

The industry best practice is to use multiple alert tiers with different windows and burn rates. A fast-burn alert (14.4x over 1 hour) catches acute incidents that will deplete 2% of the monthly budget per hour. A slow-burn alert (1x over 3 days) catches chronic degradation that might otherwise go unnoticed.

Practical Implementation

Most monitoring platforms now support burn rate alerting natively. Prometheus has built-in recording rules for multi-window burn rate. Datadog, Google Cloud, and Grafana Cloud offer SLO-based alerting with configurable burn rate thresholds.

Budget Remaining vs Burn Rate

Burn rate tells you the speed; remaining budget tells you the amount. Together they give a complete picture. A high burn rate with a full budget is less urgent than a moderate burn rate with almost no budget remaining.

Frequently Asked Questions

• What is a burn rate in SRE?

  A burn rate measures how fast the error budget is being consumed relative to the expected pace. A burn rate of 2.0 means the budget is being consumed twice as fast as sustainable, and it will run out halfway through the SLO window.

• What burn rate should trigger an alert?

  Google recommends multiple alert tiers: 14.4x burn rate over 1 hour (page immediately), 6x over 6 hours (page), 3x over 1 day (ticket), and 1x over 3 days (warning). This provides progressive escalation based on severity.

• How is burn rate different from error rate?

  Error rate is the raw percentage of failing requests. Burn rate normalizes this against your SLO and time window. A 1% error rate might be harmless for a 99% SLO or catastrophic for a 99.99% SLO — burn rate captures this context.

• What is multi-window burn rate alerting?

  Multi-window alerting checks burn rate over both a long window (for trend) and a short window (for recency). An alert fires only if both windows exceed the threshold, reducing false positives from brief spikes or historical noise.

• Can the burn rate be negative?

  No. The burn rate is always zero or positive because errors can only accumulate, not un-occur. However, the effective rate can decrease if the service returns to normal operation, lowering the rolling-window average.

• How do I reduce a high burn rate?

  Identify the source of errors (deployment, infrastructure issue, external dependency) and remediate it. Roll back recent changes, scale resources, or enable fallbacks. Once the error source is resolved, the burn rate will decrease over the rolling window.