Calculator · SRE

Error Budget Calculator.

Input your SLO target, window, deploy cadence and change-fail rate — see your error budget in minutes, expected burn rate, and when you’ll exhaust it. Aligned to the Google SRE Workbook error-budget policy and DORA 2024 change-fail rate benchmarks.

Inputs

SLO — availability target99.9%

User-journey SLO, not infrastructure uptime. Pick from what users experience.

Measurement window

28-day rolling is the Google SRE default; quarterly is APRA CPS 230-friendly.

Deploys per day5

DORA 2024: Elite ≥1/day; High weekly-daily; Medium weekly; Low monthly-quarterly.

Change-fail rate12%

DORA 2024: Elite <5%; High 5-10%; Medium 10-15%; Low 30%+.

MTTR per failed change (minutes)25

Elite <1h; High <1d; Medium 1-7d; Low >1mo.

Baseline (non-change) incidents per window3

Avg baseline incident MTTR (minutes)45

How the calculation works

Error budget = window×(1−SLO). Expected change-driven downtime = deploys×CFR×MTTR. Total expected = change downtime + baseline incidents. Burn rate = total expected ÷ budget.

Time-to-exhaustion projects the current burn rate forward. A burn rate above 1.0 means you will breach SLO before the window ends. Below 1.0 means feature work continues; above means reliability work prioritises (per the SRE Workbook error-budget policy).

The multi-window multi-burn-rate alerting thresholds (14.4× over 1h pages; 6× over 6h tickets) are the Google SRE Workbook reference. Tune to your incident SLA.