How do I set up weights in the right order?

Hello all,
I am totally new to all this, so please bear with me.
I am trying to set up weights in ascending order in a dropdown menu format. Such as 20g first, 40g second etc.
All is ok until I add Kilos to the list, then then Kilos (5 Kilo, 10 Kilo, 25 Kilo) jump to the top of the dropdown list and it looks really bad.
What I want is to display the weights in a drop down menu from 20g 40g, 80, etc and have the Kilo weights come after them.
I have been trying for days to get it to work, but no luck.
Can someone here please tell me the secret?
regards
Ged

I trust you are working with attributes?

Yes I am,
Even when I use the default setting to put them in order, the 5, 10, 25 Kilo weights come first in the dropdown menu.
Is this something to do with the way they are sorted, ie, 10 comes before 20, so that 10 Kilo is befoe 20g?
I am still slogging hard at it.

The sort order is determined when you ADD (or later EDIT) the option VALUES to any given option NAME.

You get the sort order the way you want it in the:

admin>>>catalog>>>option value manager.

EDIT each VALUE (for the option NAME in question) and set the sort order according to your needs.

Then, to apply your DEFAULT sort settings across products/categories, use:

admin>>>catalog>>>option value sorter