hCG Levels by Week: What's Normal and What Tests Can See

hCG — human chorionic gonadotropin — is pregnancy's signature hormone: produced by the implanting embryo's support cells, doubling relentlessly in early weeks, and the only thing any home test detects. Here's the shape of a typical curve, with the caveat that "typical" spans an order of magnitude.

Blood ranges by week (from last menstrual period)

• 3 weeks (≈ implantation): 5–50 mIU/ml
• 4 weeks (missed period): 10–425
• 5 weeks: 20–7,000
• 6 weeks: 1,000–56,000
• 7–8 weeks: 7,600–230,000
• 9–12 weeks: peak, often 25,000–290,000
• Second trimester onward: declines and plateaus around 10,000–50,000

Read those spreads again: at 5 weeks, one healthy pregnancy measures 100 and another 7,000. This is why clinicians care about doubling over 48 hours far more than any single value, and why comparing your beta to a friend's is meaningless.

Urine lags blood

Urine hCG roughly tracks blood but runs lower and noisier — typically half or less of serum concentration, swinging with hydration and hold time. A blood level of 25 can be a urine level of 10 in the morning and 4 after lunch, which is the entire case for first-morning urine.

Mapping levels to test behavior

• ~10–25 mIU/ml urine: the faint-line zone for sensitive tests — usually 9–13 DPO.
• Hundreds: bold lines; digitals commit confidently.
• Thousands: strips saturate — progression ends, dye stealers appear.
• Very high (late 1st trimester): the hook effect can paradoxically fade lines.

What raises or lowers the curve

Higher-than-average: multiples (with huge overlap — not a twin test), molar pregnancy. Lower or slower: late implantation, ectopic pregnancy (often slow-rising — why pain plus positive test needs prompt care), some early losses. After a loss, the down-slope has its own timeline — see hCG after miscarriage.

The takeaway for home testers

Home strips are a threshold instrument reading a noisy signal: they say "above/below ~10–25 in this sample," nothing finer. Trends across 48-hour steps — read consistently, ideally by the AI Pregnancy Test Checker rather than memory — are the only home-readable signal, and the real numbers belong to your clinician's lab.

The bottom line

hCG climbs from single digits at implantation to six figures by week 10, with healthy ranges so wide that only direction matters. Strips read thresholds, betas read numbers, and 48 hours is the unit of truth.

This guide is for education only and is not medical advice. Home tests can be wrong in both directions — confirm any result with a clinician, and contact one promptly if you have pain, heavy bleeding or feel unwell.