Hosting

SLA Downtime Calculator

Turn an uptime target such as 99.9% into the maximum downtime allowed over a day, week, month, or year.

Last reviewed: April 30, 2026Free toolMethodology

SLA Downtime Calculator

These fields start with sample inputs. Keep them or replace them, then run the tool to show a fresh result.

Number fields accept plain values and common formatted input such as 250000, 250,000, or 1,234.56.

Result

Calculating the sample result.

Why it matters

SLA numbers are easier to reason about when translated into actual downtime budgets rather than abstract percentages.

When to use

  • Planning reliability targets
  • Explaining SLA commitments to non-technical stakeholders
  • Comparing different availability objectives

Inputs & Outputs

Inputs

  • SLA percentage is the target availability level.
  • Period defines the window over which the downtime budget is calculated.

Outputs

  • Allowed downtime shows the maximum outage time compatible with the target.
  • Availability buffer helps communicate how tight the reliability budget really is.

Downtime budget method

Calculate the downtime share from the availability target, then apply that share to the total minutes in the selected period.

Allowed downtime = total period time x (1 - uptime target)

Worked example

1

Target translation

A team wants to understand what 99.95% means over a year.

Inputs

  • SLA target: 99.95%
  • Period: year

Steps

  • Downtime share = 0.05%
  • Apply the share to the total minutes in a year

Result

  • The tool converts the target into an annual downtime budget in minutes and hours.

Edge cases & caveats

  • Calendar-based reporting windows can vary slightly by month.
  • A downtime budget does not say anything about outage timing or severity.

Frequently Asked Questions

Why is yearly downtime still useful if I report monthly?

Because the annual view helps show the true operational cost of even small changes in uptime targets.

Can I use this for internal SLOs too?

Yes. The same math works for internal targets and external SLAs.

Keep going

Related Tools

hosting

Uptime Percentage Calculator

Calculate uptime percentage from total downtime over a selected period.

Open
developer

Response Time Converter

Convert response times between microseconds, milliseconds, seconds, and minutes.

Open
developer

Time Duration Calculator

Convert a time duration into alternate units and summarize the same length of time in a more readable form.

Open