Error Budget Consumed

SRE planning metric. Over 100% means you have exhausted the budget for the period.

Allowed downtime = period × (1 − SLO/100); consumed % = downtime ÷ allowed × 100.

Tip: Keep “SLO (%)” and “Period Length” on the same basis (currency, tax treatment, and time period) before you calculate.

Cluster: DevOps hub · Software Testing hub · Percentage guide

Error budget consumed shows how much of the allowed unreliability for an SLO you’ve used.

Enter SLO (%), period length, and downtime in the same time unit as the period.

%
Availability SLO target
Period duration (e.g. minutes)
Observed downtime (same unit)

Error Budget Consumed

Understanding Error Budget Consumed

How we calculate. Allowed downtime = period × (1 − SLO/100); consumed % = downtime ÷ allowed × 100. See our methodology and accuracy policy .

Real-world scenario: A typical Error Budget Consumed case uses slo (%) 99.9 and period length 43200. Enter the same figures below to reproduce the worked path.

What is Error Budget Consumed?

SRE planning metric. Over 100% means you have exhausted the budget for the period.

  • SLO is availability target (e.g. 99.9)
  • Period and downtime same unit
  • >100% = budget exhausted

The Formula

Error Budget Consumed
Consumed % = Downtime ÷ (Period × (1 − SLO/100)) × 100

Worked Example

Scenario: SLO 99.9%, period 43,200 minutes (30 days), downtime 30 minutes.
Step 1: Allowed = 43200 × (1 − 0.999) = 43.2 minutes
Step 2: Consumed = (30 ÷ 43.2) × 100 ≈ 69.44%
Answer: 0.2% (part ÷ whole × 100; verified with this calculator).

Common Use Cases

  • Release freezes: budget gates
  • SRE reviews: burn rate narrative
  • Multi-service SLOs: compare burn

Pro Tips

  • Align downtime with SLO filter
  • Track remaining % as 100 − consumed
  • Use rolling windows when contracts require
ScenarioWhen to use
Percent of a numberFinding a part of a whole (tax, tip, score)
Percent changeComparing old vs new values

Limitations: Error Budget Consumed results are educational DevOps/FinOps planning aids—not SLAs or billing guarantees. Confirm definitions with your platform and finance policies.

Common mistakes

  • Swapping part and whole: The denominator must be the full total, not a subset.
  • Rounding too early: Carry extra decimal places through multi-step work before rounding the final percent.
  • Mixing percent and decimal forms: Enter rates in the format the calculator labels expect.

When to use this calculator

  • Use this page when your wording matches error budget consumed and the form labels on screen.
  • Use percent of a number for “what is X% of Y?” problems.
  • Use number is what percent when you know part and whole and need the percent.

Still unsure about error budget consumed? Start with the quick answer above, then open the linked calculator that matches your wording.

Frequently Asked Questions

How do I use this error budget consumed calculator?

For error budget consumed, enter the values labeled on the form, then press Calculate. Compare the result to the worked example on this page.

What formula does this page use?

See the quick answer and formula box above for error budget consumed—the same percentage calculator expression is applied to your inputs.

What if my result looks wrong?

When checking error budget consumed, re-check part vs whole (or rate vs base), rounding, and whether percents were entered as 25 rather than 0.25 when the form expects percents.

Authoritative References

For DORA and FinOps definitions, consult: