I was told that the left stroke of the „roof“ in 给 should be longer than the right one.
Or in 田 all the strokes have to be connected. In Skritter it often isn`t.
The radical 58 彐looks different in different characters, for instance 当or 争.
Does anybody know how important the stroke length is in the HSK writing test?

My guess is that if they can read the character, you are fine.

You can do the HSK writing test electronically (type using a pinyin IME), which implies to me that it is the content that they are worried about, not the handwriting.

Take a look at a native speaker's handwriting sometime and see if they worry about those little details. Or you could try entering those characters in here and selecting one of the handwriting cursive fonts (e.g. the last one in group 3) - some of the strokes don't even exist! http://www.chinese-tools.com/tools/calligraphy.html

Alan, thanks for you answer. I think I have to write with a pencil at the HSK. If radicals like 天/夫 失/矢 are not properly written then the character is wrong I guess. But how about the others?

(I double checked with a native speaker...) I don't know about the HSK specifically, but in general stroke length doesn't matter too much. However, the 'topology' of the character does matter if there is a similar character that it can be confused with; so distinguishing between strokes that intersect and strokes that just touch (such as 已/己 and 天/夫) is important.

That sounds good! Thanks again.

I think someone who tells you that the left stroke should be longer than the right stroke is picking at your writing too much. Just today I saw a teacher leave the "roof" off a character and every single student understood what she wrote.

I'm not saying you should learn the wrong way, but I do believe people shouldn't get caught up in the minute details. If you say diferent in English, we will know you meant different...

*i am lucky enough to live in Taiwan while learning at the same time, it never ceases to amaze me when it comes to how bad they write/mess up a character and it is still very well understood.

** you should see the arguments that start for characters like 龜, it will make everything else seem silly. And characters that are like 電 or 雨, the direction of the strokes varies between whoever is writing it.