Which of these or any other option would you recommend?
Which of these are grammatically wright?
1- How many kilogram is it?
2- How many kilograms is it?
3- How many meter is it?
3- How many meters is it?
4- How heavy is it?
5- Hoe long is it?
My best wishes for your new year.
riquecohen answered your question about grammatical correctness.
I'd just note that 5 is more natural than 3; 4 is more natural than 2 - with 'how much does it weigh?' even more natural.