Lesson Hours Calculator
A teaching period is not an hour, and across most of Europe it is 45 minutes — three quarters of one. That gap is small enough to ignore per lesson and large enough to matter across a timetable: twenty-five lessons a week is under nineteen clock hours, not twenty-five. This converts a timetable into the hours a contract is actually written in.
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The 45-minute hour
Most of continental Europe runs school on a period of 45 minutes. It is the lektion in Denmark, the Unterrichtsstunde in Germany, Austria and Switzerland, the lekcja in Poland, and the same length again across much of central and eastern Europe. The convention is old and remarkably durable, and it is why a teacher’s timetable and a teacher’s contract are written in two different units.
The conversion is the easy part: 45 minutes is 0.75 hours, 50 minutes is 0.83, 60 is 1.0. The part worth being careful about is what you then compare it to.
Contact time is not working time
The single most misleading thing you can do with the figure above is treat it as a working week. Twenty-five lessons at 45 minutes is 18 hours 45 minutes of teaching, and a teacher on that timetable is not working an 18-hour week. Preparation, marking, parent contact, meetings, cover, supervision and administration all sit outside it, and in most systems they occupy at least as many hours as the teaching does.
This is precisely why the share shown above is reported alongside the remaining hours rather than on its own. In the Danish system the whole job is a 37-hour week within an annual norm, and teaching is one component of it. German Deputat works the other way round, fixing the number of lessons and leaving the rest of the week undefined. Both describe the same reality: the timetable is the visible part of a larger job.
Where the annual figure is useful
Multiplying a weekly timetable by teaching weeks gives a number that is genuinely comparable — between colleagues, between subjects, between schools, and between one year’s allocation and the next. It is the figure to reach for when a timetable change is proposed and you want to know whether it is actually a change in load. Two extra lessons a week is around 60 clock hours a year, which is a substantial reallocation dressed up as a small one.
Lesson length is not fixed
Schools shorten periods to fit more subjects into a day, and a 40-minute period is not unusual. Because the total is a product, a five-minute cut applied across twenty-five lessons removes just over two hours of teaching a week — more than a full lesson — without anything appearing to change on the timetable. Changing the length field above and comparing the annual figures is the quickest way to see the size of such a proposal.
A note on double periods and blocks
A double period is normally two lessons for the purposes of load, even when it runs as a single 90-minute block, and block scheduling of 80 or 90 minutes usually counts as the equivalent number of standard periods. If your school counts blocks rather than periods, enter the block length and the number of blocks instead — the arithmetic is the same, and the annual figure remains comparable.
Frequently asked questions
How many hours is a 45-minute lesson?
0.75 hours. Three lessons make two and a quarter hours, and four make three.
How many clock hours is 25 lessons a week?
At 45 minutes each, 18 hours 45 minutes, or 18.75 in decimal. At 50 minutes it is 20 hours 50 minutes.
Is teaching time the same as working time?
No, and treating it that way understates the job badly. Preparation, marking, meetings and supervision sit outside the timetable and in most systems take at least as long as the teaching.
Which countries use 45-minute lessons?
Denmark, Germany, Austria, Switzerland, Poland and much of central and eastern Europe. The Netherlands commonly uses 50 minutes, and UK and US schools typically run 50 to 60.
How do I compare two timetables fairly?
Convert both to clock hours a year. Lesson counts are only comparable when the lessons are the same length, and annual hours remove that problem.
Does a double period count as one lesson or two?
Two, in almost every system, even when it is timetabled as a single block. Enter it by length or by count — the annual total comes out the same.