How hard is it to make sleeves shorter?

[Fiftyisthenewsixty]

I have a cotton dress with long sleeves and I want short sleeves. Can I just chop them off and hem them???

This should be pretty straightforward depending on the cut of the sleeve end. It may be more difficult if the fabric has stretch.

depending on the fabric and dress, you don’t even necessarily have to hem. With some knits you can just let the fabric roll naturally into a thin edging. It won’t fray.

or with some fabrics and dresses, making a well shaped sleeve will be a nightmare of slippery fabric that fights you constantly.

It's a sort of light denim - chambray?

If it has a cuff, pick the cuff off, shorten the sleeve then sew the cuff back on. Or, simply cut and hem.

I do this often. I like faffy sleeves in principle, but hate them in practice.

Yes. Ideally hem them to match rest of garment but for short sleeves a 2cm hem is usual.

Chambray will be a nice stable fabric to sew with.

Chambray will be very easy.