Progesterone to Estrogen Ratio Calculator

The Pg/E2 ratio is used to assess female hormone balance, particularly during the luteal phase of the menstrual cycle. It helps identify conditions like estrogen dominance, supports fertility evaluation, and is used to predict outcomes of in vitro fertilization (IVF). A low ratio may indicate that estrogen is disproportionately high relative to progesterone.

The ratio is calculated by dividing the progesterone level (in ng/mL) by the estradiol level (also converted to ng/mL). Since estradiol is typically reported in pg/mL, you divide it by 1000 before computing the ratio. The formula is: Pg/E2 = Progesterone (ng/mL) ÷ Estradiol (ng/mL).

During the luteal phase, a Pg/E2 ratio between 100 and 500 is generally considered healthy when estradiol is within its normal luteal range. Values below 100 may suggest estrogen dominance, while very high ratios could indicate low estradiol or elevated progesterone relative to estrogen.

The ratio is most meaningful when measured during the luteal phase of the menstrual cycle, typically around 7 days after ovulation (cycle days 19–22 in a standard 28-day cycle). It can also be assessed at other points in the cycle but the reference ranges differ by phase.

Yes. An imbalanced Pg/E2 ratio — especially estrogen dominance (low ratio) — can interfere with implantation and early pregnancy maintenance. Adequate progesterone relative to estrogen is critical for preparing the uterine lining and supporting a fertilized egg. Clinicians often use this ratio when evaluating fertility treatment protocols.

A low Pg/E2 ratio may be associated with PMS, irregular or heavy menstrual periods, bloating, mood swings, breast tenderness, and difficulty conceiving. These symptoms can arise when estrogen levels are disproportionately high compared to progesterone, a state commonly referred to as estrogen dominance.

Because progesterone is typically measured in ng/mL and estradiol in pg/mL, direct division would give a misleading result. The calculator automatically converts both values to the same unit (ng/mL) before dividing. For reference: 1 nmol/L of progesterone ≈ 0.3144 ng/mL, and 1 pmol/L of estradiol ≈ 0.2724 pg/mL.

Not necessarily in absolute terms — estradiol is measured in much smaller quantities (pg/mL) than progesterone (ng/mL). Once both are on the same scale, healthy women in the luteal phase typically show progesterone values far exceeding estradiol, yielding a ratio in the 100–500 range. The ratio gives more meaningful clinical context than comparing raw numbers alone.