Error Budget and Burn Rate Calculator (SLO)
Error budget, burn rate and time until the budget runs out, from an SLO, the error rate you are seeing and the SLO window.
Results
Burn rate (1 = budget lasts exactly the window)
5.00
×
Error budget (share of requests allowed to fail)
0.1000
%
The same budget as downtime in the window
43.2
min
Time until the budget is gone at this rate (0 = no errors)
6.00
d
Share of the whole budget burned in that time
0.69
%
What this tool does
An SLO of 99.9 % over 30 days allows 0.1 % of requests to fail, or about 43 minutes of full outage: that allowance is the error budget. The burn rate says how fast you are spending it: 1 means the budget lasts exactly the window, 10 means it is gone in a tenth of the window. The arithmetic also shows why alerts on a fast burn matter: at a burn rate of 14.4, one hour uses 2 % of a 30-day budget, so a few hours of it can wipe out a large part of the month.
Formula
error budget = 1 − SLO · burn rate = error rate ÷ (1 − SLO) · time to exhaust = window ÷ burn rate
Variables
| Symbol | Meaning | Unit |
|---|---|---|
slo | Availability target (SLO) | % |
er | Error rate you are seeing now | % |
w | SLO window | d |
ob | How long the errors have lasted | h |
BR | Burn rate (1 = budget lasts exactly the window) | × |
EB | Error budget (share of requests allowed to fail) | % |
DT | The same budget as downtime in the window | min |
TL | Time until the budget is gone at this rate (0 = no errors) | d |
BB | Share of the whole budget burned in that time | % |
Worked example
- Availability target (SLO)99.9 %
- Error rate you are seeing now0.5 %
- SLO window30 d
- How long the errors have lasted1 h
- Burn rate (1 = budget lasts exactly the window)5.00 ×
- Error budget (share of requests allowed to fail)0.1000 %
- The same budget as downtime in the window43.2 min
- Time until the budget is gone at this rate (0 = no errors)6.00 d
- Share of the whole budget burned in that time0.69 %
Limitations
- The result is an estimate based only on the values you type. Real situations often include factors this calculator does not know about.
- The calculation runs at full precision and only the display is rounded. If you copy an intermediate value and retype it, small differences can appear.