Speaking roughly, normal levels of thyroid-stimulating hormone (TSH) are in the range of 0.4 to 4.0 mIU/L. However, each laboratory and test manufacturer identifies its own normal TSH range.This is based on the test, the equipment being used, and the patients being tested.The American Association of Clinical Endocrinologists has proposed a range of 0.3 to 3.0 for normal TSH levels.owever, each laboratory and test manufacturer identifies its own normal TSH range. This is based on the test, the equipment being used, and the patients being tested. The American Association of Clinical Endocrinologists has proposed a range of 0.3 to 3.0 for normal TSH levels.