HCG Calculator
Calculate your HCG doubling time to track early pregnancy progression. Enter two HCG test results to determine if your levels are rising appropriately.
What is a normal HCG doubling time?
In early pregnancy (up to 6 weeks), HCG typically doubles every 48-72 hours. Doubling time of 48-72 hours indicates healthy pregnancy progression. After 6 weeks (HCG >6,000), doubling time slows to 96+ hours, which is normal. Doubling time <48 hours or >72 hours in early pregnancy may warrant monitoring. Single HCG value less useful than doubling pattern - two measurements 48-72 hours apart show trend.
What HCG levels indicate pregnancy?
HCG levels by week (from last period): 3 weeks: 5-50 mIU/ml, 4 weeks: 5-426, 5 weeks: 18-7,340, 6 weeks: 1,080-56,500, 7-8 weeks: 7,650-229,000. Wide normal range - focus on doubling pattern, not absolute number. HCG <5 = not pregnant, 5-25 = borderline (retest), >25 = pregnant. Levels peak at 8-11 weeks then decline. Low or slowly rising HCG may indicate ectopic pregnancy or miscarriage.
Can HCG levels predict twins?
Higher HCG levels MAY indicate twins but not reliably. Twin pregnancies often have 30-50% higher HCG than singleton, but ranges overlap significantly. You can't diagnose twins from HCG alone - need ultrasound. Some singleton pregnancies have very high HCG, some twin pregnancies have normal HCG. Factors affecting HCG: Implantation timing, placental development, individual variation. Focus on doubling time (healthy progression) rather than absolute value for twins.
Why is my HCG not doubling every 48 hours?
Slower doubling may indicate: Ectopic pregnancy (HCG rises slowly, may plateau), impending miscarriage (HCG stops rising or decreases), miscalculated conception date, normal variation (72-hour doubling still healthy). After 6 weeks, slower doubling is NORMAL (96+ hours). One slow rise doesn't confirm problem - repeat testing and ultrasound needed. Contact doctor if: HCG decreasing, severe pain, heavy bleeding, doubling time >72 hours before 6 weeks.