Error Budget Burn Rate Calculator
From a service-level objective and the error rate you are seeing, how fast the error budget is burning, how long until it is gone, and whether the budget consumed so far is ahead of or behind the calendar.
A 99.
How the error budget burn rate calculator works
A 99.9% objective over 30 days allows 0.1% of requests to fail — the error budget, about 43 minutes of full outage. Burn rate is the observed error rate divided by that allowance: at a burn rate of 1 the budget lasts exactly the window; at 10 it is gone in three days.
The standard multi-window alerts fire at a burn rate of 14.4 over one hour, which consumes 2% of the budget, and 6 over six hours for 5%. The other question is whether the budget used so far is ahead of the days elapsed.
Formula: budget = 1 − SLO; burn rate = error rate / budget; time to exhaust = window / burn rate
Worked examples
| Inputs | Burn rate | Note |
|---|---|---|
| 0.5% errors against a 99.9% SLO | 5 | burn rate 5 — page |
| Within budget | 0.5 | burn rate 0.5 |
| A full outage | 1,000 | gone in under an hour |
FAQFrequently asked questions
What is an error budget?
The failure the objective permits: one minus the SLO, over the window. A 99.9% monthly SLO allows about 43 minutes of full outage or 0.1% of requests failing all month.
What is burn rate?
How many times faster than the window allows the budget is being spent. Burn rate 1 spends exactly the budget by the end of the window; 10 spends it in a tenth of the time.
Where do 14.4 and 6 come from?
Google's multi-window alerting: a burn rate of 14.4 over an hour consumes 2% of a 30-day budget, and 6 over six hours consumes 5%. They balance detection speed against false pages.
What should I do when the budget is spent?
That is the policy decision the budget exists for: freeze feature launches and spend the time on reliability until the window rolls over.
Does the pace check matter?
It is the calm version of the same question. A budget 50% used ten days into a 30-day window is on course to run out, even if nothing is burning right now.
Where these figures come from
- IEC 80000-13 — Information science and technology (quantities and units) — the decimal (kB, MB) versus binary (KiB, MiB) prefixes used throughout
- RFC 4632 — Classless Inter-domain Routing (CIDR) — the address-plan arithmetic behind the subnet calculator
- RFC 1918 — Address Allocation for Private Internets — the private ranges the subnet calculator recognises
- NIST SP 800-63B — Digital Identity Guidelines, Authentication — length over composition rules; the basis of the password guidance here
- NIST SP 800-57 Part 1 — Recommendation for Key Management — key-strength comparisons used by the key-space calculator
- National Cyber Security Centre — password guidance — UK national guidance on password policy
Last checked: September 2026. Units follow the SI decimal convention (IEC 80000-13 defines the binary alternatives); network and security figures cite the defining standard.