Progesterone-to-Estrogen Ratio Calculator
Compute a progesterone-to-estradiol (P/E2) ratio by mass. Enter progesterone in ng/mL and estradiol (E2) in pg/mL; the tool matches the units and divides. There is no validated clinical cutoff, so treat the result as informational.
Example: with Progesterone (ng/mL) 12 · Estradiol / E2 (pg/mL) 150 → Progesterone : estradiol ratio: 80 : 1 (progesterone to estradiol, by mass).
- Descriptive bandLower ratio — relatively more estrogen by mass
- Important contextNo validated clinical cutoff exists, and the numbers swing hugely with cycle timing. Informational only — not a diagnosis of hormone imbalance.
Computed by the calculator below using its default values. Change any input to see your own numbers.
Ratio (by mass) = progesterone (ng/mL) ÷ estradiol (ng/mL), where estradiol in ng/mL = pg/mL ÷ 1000. So ratio = progesterone × 1000 ÷ estradiol(pg/mL). No standardized reference range exists.
What the ratio is — and what it is not
Progesterone and estradiol are reported in different units: progesterone in nanograms per milliliter, estradiol in picograms per milliliter, a thousand times smaller. To compare them meaningfully you first put them on the same footing, converting estradiol to ng/mL by dividing by 1,000, then divide progesterone by estradiol. The result is how many times more progesterone than estradiol you have by mass. This page uses that transparent definition, but be warned that other sites define the P/E2 ratio differently, so numbers are not comparable across tools.
Crucially, there is no standardized, validated reference range for this ratio. It is popular in wellness discussions of 'estrogen dominance', but mainstream endocrinology does not use a fixed cutoff. Both hormones swing dramatically across the menstrual cycle, so a single ratio without knowing the cycle day says very little.
Why timing dominates the number
Estradiol peaks just before ovulation, then progesterone surges in the luteal phase after the ovary releases an egg. A blood draw in the follicular phase, when progesterone is near zero, produces a tiny ratio; the same person tested around day 21 can show a far larger one. That is why clinicians interpret progesterone and estradiol against the specific cycle day and the reason for testing, not as a bare ratio.
How it’s calculated
Ratio = progesterone (ng/mL) ÷ estradiol (ng/mL), with estradiol converted from pg/mL by dividing by 1,000. Equivalently, ratio = progesterone × 1,000 ÷ estradiol(pg/mL). Descriptive bands (lower/mid/higher) are illustrative only and carry no diagnostic weight.
There is no validated clinical cutoff for this ratio, and definitions differ between sources. Levels depend heavily on cycle phase, assay, and whether you are on hormones. This is informational, not a diagnosis of estrogen dominance or deficiency — see an endocrinologist or OB-GYN.
Typical hormone levels by cycle phase (approximate)
| Cycle phase | Estradiol (pg/mL) | Progesterone (ng/mL) |
|---|---|---|
| Follicular | 30 – 120 | Under 1 |
| Mid-cycle (ovulation) | 130 – 370 | 1 – 2 |
| Luteal | 70 – 250 | 2 – 25 |
| Postmenopausal | Under 30 | Under 1 |
Source: approximate adult reference ranges; labs and assays vary. Values shown to illustrate cycle timing, not to diagnose.
Common mistakes
- Comparing a ratio from this tool with one from another site — the definitions differ.
- Reading a ratio without the cycle day, which drives both hormones.
- Treating a low or high ratio as proof of 'estrogen dominance', a term without a lab definition.
- Mixing units — progesterone is ng/mL, estradiol pg/mL, a thousandfold apart.
Frequently asked questions
How is the progesterone-to-estrogen ratio calculated here?
Progesterone in ng/mL is divided by estradiol converted to ng/mL (pg/mL divided by 1,000). That equals progesterone times 1,000 divided by estradiol in pg/mL. For 12 ng/mL and 150 pg/mL, the ratio is about 80 to 1 by mass.
What is a normal P/E2 ratio?
There is no standardized, validated cutoff. Mainstream endocrinology does not use a fixed ratio, and different sources define it differently, so no single normal value applies. Interpret the individual hormones with your cycle day instead.
Why does the cycle day matter so much?
Estradiol peaks near ovulation and progesterone surges afterward in the luteal phase. A follicular draw yields a tiny ratio and a luteal draw a much larger one, so the same person varies widely within one month.
Does a low ratio mean estrogen dominance?
Not in any validated sense. 'Estrogen dominance' is a wellness term without an agreed lab definition. A ratio alone cannot establish it; symptoms and properly timed testing interpreted by a clinician are needed.
Who should interpret my hormone results?
An endocrinologist or OB-GYN. They account for cycle timing, symptoms, medications, and assay differences that a bare ratio ignores. Use this tool for understanding, not diagnosis or treatment decisions.