hCG Levels Calculator

mIU/mL
mIU/mL
hr
Health

Look up expected hCG levels by gestational age and doubling time during early pregnancy.

Formula

Doubling time = ln(2) / ln(hCG₂/hCG₁) × hours between samples
  • Expected doubling: every 48–72 hours in early viable pregnancy.
  • Minimum 53% rise in 48 hours for viable intrauterine pregnancy.
  • Doubling time > 72 hr or fall: investigation for ectopic or non-viable pregnancy.
  • hCG does NOT help distinguish intrauterine from ectopic location.

hCG 1200 → 2400 in 48 hours

Inputs
  • First hCG Value: 1200 mIU/mL
  • Second hCG Value: 2400 mIU/mL
  • Hours Between Tests: 48 hr

Doubling time = ln(2)/ln(2) × 48 = 48 hours. Normal doubling.

Frequently asked questions

At what hCG level is a gestational sac visible on ultrasound?
A gestational sac is usually visible on transvaginal ultrasound at hCG 1500–2000 mIU/mL. If hCG > 2000 and no intrauterine sac, ectopic pregnancy must be excluded.