Calculate SLA business hours, step by step

A deadline in business hours counts only the hours when IT is working. Say support runs from 08:00 to 17:00 and a ticket with an eight-hour resolution target arrives on Friday at 15:00. It is due on Monday at 14:00, not on Friday at 23:00 (assuming no public holiday). Here is how to calculate it, including public holidays, pauses and three examples.

By 404desk editorial teamUpdated: 11 November 2026 · from the day-to-day work of an in-house IT team

At a glance

Set your business hours, holiday region and targets for each priority. Count only minutes within business hours, and stop the clock when you are waiting for someone else. The response target and the resolution target are two separate clocks.

The terms

SLA: Service level agreement. In internal IT it is usually a commitment rather than a contract: how quickly you respond and how quickly you resolve.
Response target: Time until the first real reply.
Resolution target: Time until the issue is resolved.
Business hours: The hours in which the clock runs, in an explicit time zone, for example Monday to Friday, 08:00 to 17:00.
Pause: Time when the clock stops because you are waiting for something you cannot influence.

What to decide first

Business hours for each weekday. Shorter on Fridays? Does the lunch break count or not?
Holiday region. German federal state, Austrian federal state or Swiss canton. Corpus Christi is not a holiday everywhere, and neither is Reformation Day.
Targets for each priority. In business hours, not calendar hours.
When the clock stops. For example, while you wait for a spare part or a reply.
Special days. Christmas Eve, New Year’s Eve, company shutdowns.

Template: support hours and targetsready to copy

Time zone: Europe/Berlin
Business hours: Mon to Thu 08:00 to 17:00, Fri 08:00 to 15:00
Public holidays: Bavaria

Priority    Response             Resolution
High        1 hour               4 hours
Normal      4 hours              8 hours (1 business day)
Low         1 business day       5 business days

Clock stops: status "Paused" (waiting for a part or a third party)

Example 1: across a weekend

Business hours are Monday to Friday, 08:00 to 17:00 (Europe/Berlin). A ticket with Normal priority and an eight-hour resolution target arrives on Friday, 13 November 2026, at 15:00.

Friday 15:00 to 17:00: 2 hours used, 6 remain.
Saturday and Sunday: the clock stands still.
Monday from 08:00: 6 hours, so the deadline is Monday, 16 November, at 14:00.

Example 2: across a public holiday

Same rules, with public holidays for Bavaria. A ticket arrives on Thursday, 31 December 2026, at 15:00 with an eight-hour resolution target. If 31 December is a normal working day:

Thursday 15:00 to 17:00: 2 hours, 6 remain.
Friday, 1 January: New Year’s Day, the clock stands still.
Saturday and Sunday: the clock stands still.
Monday, 4 January 2027, from 08:00: the deadline is at 14:00.

Example 3: with a pause

A ticket with High priority arrives on Tuesday, 10 November 2026, at 09:00 with a four-hour resolution target. At 10:00 it turns out that a power supply has to be ordered. The ticket goes to Paused, with 1 hour used. The part arrives on Thursday at 11:00 and the ticket goes back to In progress. From 11:00 the remaining 3 hours run, and the deadline ends on Thursday at 14:00.

What matters is that pauses stay honest. Putting a ticket on Paused because you cannot keep up makes every analysis worthless.

Common mistakes

Calendar hours instead of business hours. Then every deadline is missed over the weekend.
One holiday region for all sites. Then your colleague in Vienna is supposedly too slow on 26 October.
Counting the automatic acknowledgement as a response. Then the response target is always met and tells you nothing.
Too many priorities. Five levels mean five arguments. Three are enough.

Which targets are realistic

Targets that are constantly missed are worthless, because nobody takes them seriously any more. Targets that are always met are too generous. A good start: look at the tickets from the last two months, at how long they took to the first reply and to the resolution, and set the target so that around nine in ten would meet it. You can sharpen it afterwards.

For one-person IT, a response target of one hour is rarely realistic if the same person also looks after servers, the network and purchasing. It is more honest to promise a response on the same working day, with a clear rule for what may come in by phone as an emergency.

Several sites and countries

If IT is based in Nuremberg and also supports a warehouse in Linz, different public holidays apply. Decide whose calendar the deadline follows: the requester’s location or IT’s. Both are defensible, as long as it is written down. Most teams use IT’s calendar, because IT is the one doing the work.

Report on deadlines honestly

Count deadlines met for each priority and overall, otherwise many small tickets hide the big ones.
Look at every missed deadline on High priority individually.
Check how often tickets were paused. If that rises, the pause may be used as a way out.
Compare months with each other, not people.

Tell people what to expect

A deadline that only IT knows about helps little. Write in the confirmation email when someone will be in touch, for example “We will get back to you today by 14:00”. That reassures people more than any ticket number and saves them asking. What matters is that the time comes from the deadline and not from a gut feeling, otherwise it becomes a promise you do not keep.

Emergencies outside business hours

What happens if the stock system fails on a Saturday while dispatch is working? A deadline in business hours does not help then. Decide whether there is an on-call service, who covers it and how to reach them, and put it in the confirmation email for tickets with High priority. Without an on-call service, the honest answer is: Monday at eight.

Calculating by hand and with software

Without software, you can approximate the deadline in a spreadsheet, using a working-day function that knows weekends and a list of public holidays, and adding the hours of the first and last day by hand. That is error-prone as soon as pauses come in. At the latest then, a tool that stops the clock itself is worth it.

In 404desk, you set business hours, country and region, and the targets for each priority. While a ticket is on “Paused”, the clock stands still, and an email warns you before a deadline is missed. See SLAs and business hours.

Frequently asked questions

What is the difference between response and resolution time?

The response target ends with the first real reply to the requester. The resolution target ends when the problem is solved. Both start running at the same time.

Does an automatic acknowledgement count as a response?

It should not. A response means that a person has read the ticket and said something about it.

How do public holidays that apply in only one federal state work?

They count for the sites in that state. If you have several sites, you need a holiday region for each site.

Does the lunch break count towards the deadline?

That is up to you. Many internal IT teams count it, because someone is still reachable. What matters is that the rule is written down.

What about a company shutdown?

Enter it as non-working days, like public holidays. Then the clock stops, and nobody wonders in January about missed deadlines from the week between Christmas and New Year.

404desk is launching soon. At launch, you can try it free for 14 days.Or let 404desk do the maths: it counts business hours and public holidays for Germany, Austria and Switzerland.

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