# SRE Burn Rate Calculator

- **URL:** https://codeasystem.com/calculators/developer/sre-burn-rate-calculator/
- **Category:** developer
- **Description:** Compute how fast you are consuming error budget relative to plan, benchmarked against Google SRE fast-burn conventions.
- **Primary output:** Burn rate: 2.78x

## Inputs
- SLO availability (name: `slo`, type: number, example: 99.9)
- Compliance window (name: `windowDays`, type: number, example: 30)
- Errors observed so far (name: `errorsObserved`, type: number, example: 120)

## Outputs
- Burn rate: 2.78x
- Allowed errors in window: 43.2 minutes
- Observed errors in window: 120 minutes
- Fast-burn threshold (1 hour): 14.4x; pages immediately (Google SRE convention)
- Fast-burn threshold (6 hours): 6x; pages within the day (Google SRE convention)
- Status: slow burn; watch

## Formula / methodology
```
burn = (observed ÷ window) ÷ (allowed ÷ window) = observed ÷ allowed
conventions: 14.4x ≈ 2% of a 30-day budget in 1 h · 6x ≈ 5% in 6 h
```

Burn rate divides your observed error rate by the rate the SLO permits. A value of 1x means spending budget exactly on schedule; higher values project breach before the window closes. The 14.4x and 6x thresholds come from Google’s multiwindow alerting conventions and are labeled here as conventions rather than laws.

## Assumptions & limitations
- Errors and budget share the same units (minutes here).
- Thresholds follow Google SRE Workbook multiwindow alerting conventions.
- Steady-state burn assumed over the elapsed period.

## How to use
1. **Enter SLO and window**; Same values as your error-budget dashboard so rates stay comparable.
2. **Enter observed errors**; Downtime minutes (or failed-request equivalents) accumulated since the window started.
3. **Compare against thresholds**; Above 14.4x page immediately; above 6x investigate same-day; between 1x and 6x watch the trend.

## Example
With a 99.9% SLO over 30 days the allowed budget is 43.2 minutes; observing 120 minutes burns at 2.78×; elevated but below the 6x paging threshold.

Result for these inputs:

```
Burn rate: 2.78x
```

## About this calculator
### Where 14.4x comes from

Burning 2% of a 30-day budget within one hour projects a 14.4x rate; small enough to catch real outages fast, large enough to ignore noise. The 6x threshold catches slower bleeds within a working day. Google published these constants in the SRE Workbook; teams tune them to their own risk tolerance.

### Multiwindow pairing

Production alerting pairs a short window (fast detection) with a long one (false-positive suppression); e.g. fire only when both 1-hour and 5-minute burn exceed threshold. This calculator gives you the single-window rate those policies build upon.

## FAQs
### What burn rate is “normal”?

Exactly 1.0x consumes the budget perfectly across the window. Sustained rates under 1 leave headroom; anything persistently above 1 ends in breach.

### Can I use requests instead of minutes?

Yes; divide failed requests by the request-denominated budget. The ratio is unit-independent.

### Why not alert on raw error count?

Counts ignore context: 100 errors matter more at 99.99% than at 99%. Burn rate normalizes against what you promised.

## Related calculators
- [Error Budget Calculator](https://codeasystem.com/calculators/developer/error-budget-calculator/)
- [Uptime SLA Calculator](https://codeasystem.com/calculators/developer/uptime-sla-calculator/)
- [API Pagination Calculator](https://codeasystem.com/calculators/developer/api-pagination-calculator/)

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Last updated: 2026-08-23 · Version: 1.0.0 · [HTML version](https://codeasystem.com/calculators/developer/sre-burn-rate-calculator/)