Progesterone to Estrogen Ratio Calculator

Created by Małgorzata Koperska, MD
Reviewed by Bogna Szyk and Steven Wooding
Based on research by
Elgindy EA. Progesterone level and progesterone/estradiol ratio on the day of hCG administration: detrimental cutoff levels and new treatment strategy. Fertility and Sterility (April 2011)
Last updated: Jan 11, 2023

The calculation of progesterone to estrogen ratio, also known as Pg/E2 or P/E2 ratio, is an essential part of female hormone balance assessment and success prediction of in vitro fertilization (IVF).

You can also use this calculator for estradiol and progesterone unit conversion by simply clicking on units to switch between ng/mL, pg/mL, and nmol/L for progesterone and pg/mL, ng/mL, and pmol/L for estradiol.

Estradiol (E2) belongs to estrogens, a group of female sex hormones. Other major estrogens are estrone (E1) and estriol (E3). Because estradiol is the most potent and most frequently measured, its concentration is used in the progesterone-to-estradiol ratio estimation.

Step one – estradiol and progesterone unit conversion

The main difficulty in calculating the progesterone to estrogen ratio is usually caused by the fact that the concentrations of the hormones are presented in different units.

Progesterone is most commonly presented in ng/mL (nanogram per liter) or nmol/L (nanomole per liter), and estradiol is presented in pg/mL (picogram per milliliter) or pmol/L (picomole per liter).

To be able to compare the two, it's necessary to express them in the same units.

  • Progesterone:

    1 ng/mL = 3.180547 nmol/L

  • Estradiol:

    1 pg/mL = 3.6713 pmol/L

Then, to go from ng/mL to pg/mL, multiply the value by 1000, or to go from pg/mL to ng/mL, divide it by 1000.

If you're confused with the unit conversion of other lab test results, check out our cholesterol unit and glucose unit converters!

Step two – estimation of the progesterone to estradiol ratio

After bringing the hormone concentrations to the same unit of measure, the calculation of the P/E2 ratio itself is straightforward:

ratio = progesterone / estradiol

Check out other ratio calculators, such as cholesterol ratio calculator.

What is progesterone to estrogen ratio used for?

It is a parameter used to determine hormonal dominance in patients with results within normal ranges of progesterone and estradiol (measured in the luteal phase of the menstrual cycle):

  • Progesterone (P or Pg): 11-29 ng/mL or 35-92 nmol/L.

  • Estradiol (E2): 19-160 pg/mL or 70-600 pmol/L.

In healthy women, the progesterone/estradiol ratio should be between 100 and 500. If it's higher than that, it may indicate progesterone domination, and if it's lower, then estrogen domination is more likely.

A specific progesterone and estradiol balance is especially important for successful conception and is estimated before the procedure of in vitro fertilization (IVF), but as the concentration of estradiol is crucial here, the ratio is usually inversed. If you're interested in this topic, check out these articles by Dr. Rehana Rehman and Dr. Irmhild Gruber:

  • Estradiol progesterone ratio on ovulation induction day: a determinant of successful pregnancy outcome after intracytoplasmic sperm injection:

    Females having a high estradiol/ progesterone ratio were able to achieve clinical pregnancy, shown by a positive βhCG and cardiac activity on transvaginal scan. These females also had a significantly high number of oocytes, endometrial thickness, and implantation rate.

    Conclusion: A high estradiol/progesterone ratio on the day of ovulation induction predicts the success of intracytoplasmic sperm injection.

  • Serum estradiol/progesterone ratio on the day of embryo transfer may predict reproductive outcome following controlled ovarian hyperstimulation and in vitro fertilization:

    During IVF-ET, controlled ovarian hyperstimulation results in excessive follicular development and supraphysiologic serum concentrations of E2 and P.

Małgorzata Koperska, MD
Ratio (Pg/E2 or P/E2)
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