Progesterone to Estrogen Ratio Calculator

Progesterone and estrogen are related reproductive hormones whose concentrations change across the menstrual cycle, pregnancy, menopause, and hormone treatment. A progesterone-to-estrogen ratio is sometimes used as a simple way to compare laboratory values, especially during the luteal phase. This calculator converts progesterone to nanograms per milliliter and estrogen to picograms per milliliter, then places both on the same mass scale by multiplying progesterone by 1,000 before division. For example, progesterone of 15 ng/mL and estrogen of 100 pg/mL produce a mass-adjusted ratio of 150 to 1. If the laboratory reports progesterone in nmol/L, the calculator divides by approximately 3.18 to obtain ng/mL. If estrogen is reported in pmol/L, it divides by approximately 3.671 to obtain pg/mL. These conversion factors are appropriate for progesterone and estradiol respectively; they should not be applied to unrelated analytes. A frequently discussed comparison band is roughly 100 to 500, but this is not a universally standardized diagnostic reference range. Laboratories generally validate each hormone separately, and clinical guidelines do not diagnose a condition from this ratio alone. The expected relationship depends heavily on the day of the menstrual cycle, whether ovulation occurred, pregnancy status, menopause, medications, and the exact estrogen assay. The word estrogen may also refer to estradiol, estrone, or total estrogens, which are not interchangeable. Timing is especially important. Progesterone is normally low during the follicular phase and rises after ovulation, while estradiol has more than one peak. A low ratio before ovulation may therefore be physiologic rather than evidence of so-called estrogen dominance. A single blood draw can also miss a hormone peak because secretion is pulsatile. Clinicians may use cycle history, ovulation tracking, repeat tests, ultrasound, and additional laboratory measurements to understand the result. Do not start, stop, or adjust progesterone, estrogen, fertility medication, or menopausal hormone therapy based on this calculator. Symptoms attributed to hormone imbalance can overlap with thyroid disease, pregnancy, medication effects, anemia, and many other conditions. Discuss abnormal bleeding, infertility, severe pelvic pain, or persistent symptoms with a qualified healthcare professional. This tool makes unit conversion and arithmetic transparent, but the laboratory's own reference intervals and a clinician's assessment remain the appropriate basis for medical decisions.