One-piece toilet

A toilet sculpted into a seamless unit. The result is a sleek toilet with no crevices between the tank and bowl.

Two-piece toilet

A toilet that have a separate tank and bowl that are bolted together upon installation.

'A' Measurment 
Round Bowl 

Measured from the middle of the two seat bolts on the back edge of the toilet (figure A) that equals 16.5 inches or less.

Elongated Bowl

Measured from the middle of the two seat bolts on the back edge of the toilet (Figure A) that equals 16.5 or more. 

'B' Measurment

For both Round and Elongated bowls, measure the distances between the center of the two bolt holes. This measurment should be between 5-7 inches.