This is what I use depending on the snake's size

Up to 500 grams – 15 Quarts (17"L x 11 1/8"W x 6 3/8"H)

Up to 1500 grams – 32 Quarts (23 1/2"L x 16 1/4"W x 6 3/8"H)

Above 1500 grams – 41 Quarts (34 3/4"L x 16 1/2"W x 6"H)