Speedy Calculator

Uptime and Downtime Calculator (SLA)

Other Updated October 25, 2026

Quick answer

The uptime calculator converts an availability percentage, such as 99.9%, into the allowed downtime per day, week, month and year, as used in service level agreements.

%
Downtime per year
—
Downtime per month
—
Downtime per week
—
Downtime per day
—

Each extra “nine” cuts allowed downtime by a factor of ten: 99.9% allows about 8.8 hours a year; 99.99% allows about 53 minutes.

How to use the Uptime and Downtime Calculator

  1. Availability

Results update as you type, and every field accepts the units shown in its menu.

How it works

The unavailable fraction is multiplied by the length of each period.

What each result means

  • Downtime per year = (1 – [Availability]÷100)×31557600
  • Downtime per month = (1 – [Availability]÷100)×2629800
  • Downtime per week = (1 – [Availability]÷100)×604800
  • Downtime per day = (1 – [Availability]÷100)×86400

Formula

Downtime = (1 − availability) × period

Worked example

Inputs — Availability: 99.9 %.
Results — Downtime per year = 8:45:58; Downtime per month = 43:50; Downtime per week = 10:05; Downtime per day = 1:26.

Frequently asked questions

What is “five nines”?

99.999%, about 5 minutes 15 seconds of downtime per year.

Does planned maintenance count?

It depends on the SLA wording.

What formula does the Uptime and Downtime Calculator use?

Downtime = (1 − availability) × period.

Cite this calculator

Speedy Calculator. (2026). Uptime and Downtime Calculator (SLA). Speedy Calculator. https://speedycalculator.com/calculators/other/uptime/