Free Progesterone to Estrogen Ratio Calculator

Progesterone to Estradiol Ratio (Pg/E2) – Key Hormone Balance Metric

The progesterone to estradiol ratio (also referred to as Pg/E2 or P/E2) is a fundamental indicator used in female endocrine health assessment. It is of particular importance during the luteal phase of the menstrual cycle and in the context of in vitro fertilization (IVF). By comparing the levels of these two major female sex hormones, clinicians can identify dominance patterns and evaluate reproductive readiness. The free online Pg/E2 ratio calculator (also a convenient hormone balance calculator) streamlines both unit conversion and ratio computation, making it a practical tool for daily monitoring.

Unit Conversion – The First Step

A typical hurdle when computing the P/E2 ratio is that progesterone and estradiol concentrations are often expressed in different units:

• Progesterone: ng/mL (nanograms per milliliter) or nmol/L (nanomoles per liter)
• Estradiol: pg/mL (picograms per milliliter) or pmol/L (picomoles per liter)

To obtain a valid ratio, both values must be converted to the same unit. The conversion factors are summarized below:

Hormone	Original Unit	Equivalent Unit	Conversion
Progesterone	1 ng/mL	3.180547 nmol/L	Multiply ng/mL by 3.180547 to get nmol/L
Estradiol	1 pg/mL	3.6713 pmol/L	Multiply pg/mL by 3.6713 to get pmol/L

Furthermore, within the weight‑volume system, 1 ng/mL = 1000 pg/mL. Hence, to convert progesterone from ng/mL to pg/mL multiply by 1000; conversely, divide by 1000 to go from pg/mL to ng/mL.

Calculating the Pg/E2 Ratio

After harmonizing the units, the ratio formula is straightforward:

$$\text{P/E2 Ratio} = \dfrac{\text{Progesterone}}{\text{Estradiol}}$$

For example, if progesterone is 10 ng/mL (10000 pg/mL after conversion) and estradiol is 100 pg/mL, the ratio would be 10000 / 100 = 100. The calculator performs this division automatically once the user inputs the measured values and selects the correct units.

Reference Ranges and Interpretation

In healthy women during the luteal phase, typical reference intervals are:

• Progesterone: 11–29 ng/mL (35–92 nmol/L)
• Estradiol: 19–160 pg/mL (70–600 pmol/L)

A balanced progesterone to estradiol ratio usually lies between 100 and 500. Deviations from this range suggest a hormonal shift:

• Ratio > 500 may indicate progesterone dominance.
• Ratio < 100 may indicate estrogen dominance.

These thresholds serve as general clinical reference points; individual results should be reviewed by a physician.

Clinical Use in IVF

The Pg/E2 ratio (and, in some protocols, its inverse – the estradiol/progesterone ratio) is frequently used in IVF to assess ovarian stimulation outcomes and endometrial receptivity. Supraphysiological estradiol levels after controlled ovarian hyperstimulation can affect the ratio, and studies have shown that an elevated estradiol/progesterone ratio on the day of ovulation trigger is associated with improved implantation and clinical pregnancy rates in ICSI cycles. Similarly, the ratio measured on the day of embryo transfer has been explored as a predictor of reproductive success. Therefore, this IVF hormone ratio provides valuable insight for tailoring treatment plans.

Limitations

While this calculator offers a rapid and user‑friendly way to compute the Pg/E2 ratio, it is intended for educational and preliminary assessment only. Hormonal interpretation requires professional medical expertise, and the tool cannot replace a consultation with a qualified healthcare provider. Always discuss your results with a doctor for appropriate diagnosis and management.