it depends from the range of MW that you would like to separate and if you are using gel at constanf acrilammide % or with grandient of acrilammide concentration:
For small protein or peptides (100KDa) you can use also tris-acetate 3-8%
if you are interested, those and other information are part of the video: Overview on SDS page, available on my blog ProteoCool at the following link
As noted by Aanuele, different percentages of Acrylamide gel can be used depending on the protein size.
Prepare 30% acrylamide mix (Add 29.22 g of acrylamide and 0.78 g of bisacrylamide to 100 ml of H2O). Filter the stock solution through Whatman filter paper and store at 4°C.
You can use this 30% acrylamide mix to prepare different percentages of acrylamide gels.