Estradiol vs Progesterone: what is the difference?

How they differ

Both are steroid hormones central to the menstrual cycle and they act in sequence rather than in competition. Estradiol dominates the first half of the cycle, building the uterine lining, and progesterone dominates the second half after ovulation, maintaining it. Structurally estradiol is the more modified: its first ring is aromatic and carries a phenol, which is what makes it an estrogen, while progesterone keeps the intact steroid skeleton with two ketones and is the direct precursor of cortisol and testosterone. Progesterone is the heavier at 314.5 against 272.4. Both are made from cholesterol, and both appear here as body-endogenous molecules rather than as medicines.

Side by side

Common questions

What is the difference between Estradiol and Progesterone?

Both are steroid hormones central to the menstrual cycle and they act in sequence rather than in competition. Estradiol dominates the first half of the cycle, building the uterine lining, and progesterone dominates the second half after ovulation, maintaining it. Structurally estradiol is the more modified: its first ring is aromatic and carries a phenol, which is what makes it an estrogen, while progesterone keeps the intact steroid skeleton with two ketones and is the direct precursor of cortisol and testosterone.

Is Estradiol bigger than Progesterone?

Progesterone is the heavier molecule, 314.5 g/mol against 272.4 g/mol for Estradiol. Estradiol is C18H24O2 and Progesterone is C21H30O2.