The normal range for an INR blood test is 0.8 to 1.1, according to WebMD. This is comparable to a PT time of 11 to 13 seconds. This test finds how long blood takes to clot.
While PT stands for prothrombin time, INR is the abbreviation for international normalized ratio, WebMD explains. INR provides a standard score for the PT test that is clear no matter which method is used or what lab does the analysis. An INR test is run to monitor the performance of blood-clotting medication such as warfarin. It is also used to help determine the reason for bleeding or bruising, monitor liver function and investigate blood disorders, MedlinePlus states.