Correct feeding size

Hey there. I have a normal about 10-11 months old. I am currently feeding him 2to bigger mice every Friday. He is almost 2 ft long, about 1 1/2-2 inches round thickest part. I was wondering if he could take a small rat. He will not eat anything but live so I am kinda worried about feeding him a rat. I watch him eat till the mice are gone. I would post pica on how big he is but I don't know how. Thanks for the advice.

You want to feed him approx. 10-15% of his body weight or a meal that is roughly as big round as the biggest part of his body.
It is highly recommended to get a digital scale. It will help with feeding the approriate sized meals and also to track your BP's growth rate.

I do have a scale. He weighs 400 grams. The two mice together weigh around 35-50the grams. I have not seen a store sell live small rats. I was thinking about seeing if I could order online. Was wondering what weight is a small rat around.

At 400 grams he should be eating a large weaned(30-45 grams) or small rat(45-80 grams).
Start checking on craigslist or call around to some reptile stores if they don't carry them they may know where you can get them from.

Edit: I didn't realize he was eating frozen thawed so you could definitely order them online from someone like rodentpro.com. Shipping can be alittle expensive unless you are ordering in larger quantities.
Also, the mice should be fine for him until you are out.