What is an error budget in SRE?

An error budget is the maximum amount of unreliability a service is allowed while still meeting its SLO (Service Level Objective). If your SLO is 99.9% availability over 30 days, your error budget is 43.8 minutes of downtime. When the budget is exhausted, reliability work takes priority over new features.

What should I do when error budget is exhausted?

When error budget runs out, the SRE principle is to freeze feature releases and focus entirely on reliability improvements until the budget resets. In practice, this means stopping deployments, doing postmortems for recent incidents, improving monitoring, and fixing the root causes of downtime.

What is the difference between SLA, SLO, and SLI?

SLI (Service Level Indicator) is the actual measured metric — e.g., request success rate. SLO (Service Level Objective) is your internal target — e.g., 99.9% success rate. SLA (Service Level Agreement) is the external contract with consequences for breach — e.g., customer refunds if below 99.5%. Error budgets are based on SLOs.

How often should I review error budget?

Most SRE teams review error budget weekly in a reliability meeting. Track it daily during incidents. Use a 28-day or 30-day rolling window rather than calendar month to avoid the "budget resets on the 1st" incentive to delay incidents until the new month.

What is a good error budget burn rate?

A burn rate of 1x means you're consuming budget exactly as fast as it accrues — you'll use it all but not exceed it. A burn rate above 2x for more than an hour is a warning sign. Google's SRE book recommends paging when burn rate exceeds 14.4x over 1 hour (consuming a 30-day budget in 2 hours).

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Error Budget Calculator

Calculate error budget consumption and remaining budget for any SLA. Track how much downtime you have left this month. Free SRE error budget calculator for reliability teams.

SLA Target (%)

Window (days)

Downtime so far (mins)

Error budget consumed23.1%

43.2m

Total budget

10m

Consumed

33.2m

Remaining

About This Tool

Track your SRE error budget consumption in real time. Enter your SLA target, the rolling window (typically 30 days), and the downtime experienced so far. The calculator shows your total error budget in minutes, how much has been consumed, and how much remains — with a visual indicator that turns red when you're burning through budget too fast. Use this to make data-driven decisions about feature velocity vs. reliability work.

How It Works

Enter your SLA target percentage — typically 99.9%, 99.95%, or 99.99%

Set the rolling window in days — most teams use 30 days (monthly) or 28 days (4-week rolling)

Enter total downtime experienced so far in minutes

See budget consumed percentage, remaining minutes, and a visual burn rate indicator

Frequently Asked Questions

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