Calculate progesterone, estradiol, or Pg/E2 ratio from any 2 values with ng/mL, nmol/L, pg/mL, or pmol/L unit conversions and steps.

Mass-concentration ratio: Pg and E2 are compared in the same mass units. This differs from a molar ratio or an unconverted ng/mL-to-pg/mL quotient. It does not diagnose a hormone condition.

Related Calculators

Pg/E2 Ratio Formula

The Pg/E2 ratio compares progesterone to estradiol after converting both values to compatible base units. This calculator uses a mass-concentration ratio: progesterone in ng/mL is multiplied by 1,000, then divided by estradiol in pg/mL. This differs from a molar ratio or an unconverted mixed-unit quotient.

Pg / E2 = (Pg × 1000) / E2
Pg = (Pg / E2 × E2) / 1000
E2 = (Pg × 1000) / Pg / E2
  • Pg/E2 = progesterone to estradiol ratio, unitless
  • Pg = progesterone, in ng/mL after conversion
  • E2 = estradiol, in pg/mL after conversion
  • 1000 = conversion factor from ng to pg

The ratio is unitless because progesterone is converted from ng/mL to pg/mL before dividing by estradiol. Estradiol cannot be zero when calculating the ratio. Solving for estradiol requires positive progesterone and a positive ratio; zero progesterone and zero ratio do not determine a unique estradiol value.

Pg and E2 Unit Conversions

Use these conversions when comparing lab results reported in different units.

Measurement From To base unit
Progesterone ng/mL multiply by 1
Progesterone nmol/L divide by 3.18 to get ng/mL (approximately multiply by 0.314465)
Estradiol pg/mL multiply by 1
Estradiol pmol/L divide by 3.671 to get pg/mL (approximately multiply by 0.272405)

Reading a Pg/E2 Ratio Result

Result factor Why it matters
Cycle timing Progesterone and estradiol change across the menstrual cycle, so timing affects the ratio.
Unit consistency The formula assumes Pg is in ng/mL and E2 is in pg/mL before the ratio is calculated.
Lab method Different labs and test methods can produce slightly different hormone values.

Quick Example

If your progesterone is 15 ng/mL and your estradiol is 150 pg/mL, the calculation is:

Pg / E2 = (15 × 1000) / 150 = 100

The Pg/E2 ratio is 100. Use the result as a calculation aid, not as a diagnosis. Lab results should be interpreted with symptoms, cycle timing, medications, and clinical context.