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Uptime Calculator

Uptime Calculator is part of Toolspire and is ready as soon as this page loads. 99.9% still allows 8 hours, 45 minutes and 36 seconds of downtime in a 365-day year. Three nines is not “almost never”. The page does not ping anything.

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On this page

What you can do here

Three windows from one percent

The headline is the year. The detail is the day and a 30-day month, so a monthly SLA and a yearly SLA are not mixed up.

A 365-day year on purpose

Leap seconds and the extra day in a leap year are left out so 99.9% has one published answer.

Nearest second

86.4 seconds in a day at 99.9% is shown as 1 min 26 sec. The raw product is not left as a long decimal.

The sequence

How to use the Uptime Calculator

  1. 1

    Type the percent from the agreement

    99.9 and 99.99 are different promises. Do not round the contract’s figure before you type it.

  2. 2

    Read the year on the headline

    That is the usual way an annual SLA is spoken. The month in the detail is 30 days, not “this calendar month”.

  3. 3

    Do not treat the number as a ping result

    Nothing is contacted. If you need to see whether a path is up right now, this page will not tell you.

Worth knowing

  • Uptime Calculator on Toolspire: downtime fraction = (100 − percent) ÷ 100. At 99.9% that fraction is 0.001.
  • A 365-day year at 99.9% allows 8 h 45 min 36 sec. The year is 365 × 86,400 seconds, not 365.25.
  • The same 99.9% allows about 1 min 26 sec a day and 43 min 12 sec in a 30-day month.
  • 100% is 0 seconds. A percent above 100 or below 0 is rejected. This page does not watch a host.

What the nines actually buy

Each extra nine cuts the allowed downtime by ten. Two nines, 99%, still leave about 3.65 days in a 365-day year. Three nines, 99.9%, leave 8 hours 45 minutes 36 seconds. Four nines leave about 52 minutes 34 seconds. The page is that multiplication and nothing else: no probe, no incident clock, no exclusion for planned maintenance. If the contract excludes a maintenance window, subtract that window yourself. The calculator will not.

FAQ

Questions about Uptime Calculator

Where does Uptime Calculator run?

Uptime Calculator runs in this tab on Toolspire. What you type or drop in is not sent to us and is not stored on a server.

How much downtime is 99.9% in a year?

8 hours, 45 minutes and 36 seconds, in a year of 365 days. Per day it is 1 minute 26 seconds, after rounding 86.4 seconds to the nearest second.

Why 365 days and not 365.25?

So the answer does not change with a leap-year average. A contract that defines a year differently needs that year length, not this one.

Does 100% mean the service cannot fail?

It means the arithmetic allows zero seconds. It does not mean a real service has been, or will be, perfect.

Will this ping my server?

No. You type a percent. The page never opens a connection.

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