Why hCG mIU/mL Equals IU/L
This is the question most people actually have: labs report beta-hCG in either mIU/mL (US) or IU/L (many other countries), and the two are numerically identical. One mIU/mL is one IU/L, because a milli-international-unit per millilitre and an international unit per litre work out to the same concentration. So there is nothing to recalculate — a result of 1,500 mIU/mL is 1,500 IU/L.
1 mIU/mL = 1 IU/L (the value does not change) hCG Levels by Week of Pregnancy
These are commonly cited ranges by gestational age, counted from the first day of the last menstrual period (LMP) — the standard way pregnancy weeks are measured, which is about two weeks more than weeks from conception. Notice how wide each range is — that is why hCG cannot pin down an exact date on its own:
| Gestational age | Typical hCG (mIU/mL = IU/L) |
|---|---|
| Not pregnant | Below 5 mIU/mL |
| 3 weeks (from LMP) | 5 – 50 mIU/mL |
| 4 weeks | 5 – 426 mIU/mL |
| 5 weeks | 18 – 7,340 mIU/mL |
| 6 weeks | 1,080 – 56,500 mIU/mL |
| 7–8 weeks | 7,650 – 229,000 mIU/mL |
| 9–12 weeks | 25,700 – 288,000 mIU/mL |
| 13–16 weeks | 13,300 – 254,000 mIU/mL |
| 17–24 weeks | 4,060 – 165,400 mIU/mL |
| 25–40 weeks | 3,640 – 117,000 mIU/mL |
hCG usually peaks around weeks 9–12 (it can exceed 200,000 mIU/mL) and then eases off for the rest of the pregnancy.
How Fast Should hCG Rise? (Doubling Time)
In a healthy early pregnancy, hCG typically doubles about every 48–72 hours. A rise of at least roughly 35–53% over 48 hours is generally reassuring. The doubling naturally slows as the level climbs — above about 1,200 mIU/mL it often takes 72–96 hours, and above 6,000 mIU/mL longer still.
Because of this, a single hCG value tells you far less than the trend across two or more tests. Switch the calculator above to the Doubling time tab and enter your two results to see the rate of rise. A slowly rising, plateauing or falling level can point to an ectopic pregnancy or miscarriage, but that judgement is always made together with symptoms and ultrasound.
Blood hCG vs Urine Pregnancy Tests
The numbers on this page are quantitative blood (serum) beta-hCG levels — an exact value in mIU/mL that can be tracked over time. A home urine pregnancy test is qualitative: it simply reports positive or negative once hCG passes a threshold (often around 20–25 mIU/mL), and does not give a number. That is why doubling time can only be followed with blood tests.
hCG After IVF and Embryo Transfer
In IVF, the first "beta" is usually drawn around 9–14 days after the transfer, and the timing depends on the embryo’s age: a day-5 (blastocyst) transfer is roughly two days further along than a day-3 transfer, so comparable hCG levels appear a little earlier. As in natural pregnancy, clinics watch the rise between two betas rather than a single value, and confirm with ultrasound.
hCG Outside Pregnancy
A level below about 5 mIU/mL is generally considered negative for pregnancy. hCG can occasionally be raised for non-pregnancy reasons, including certain tumours, so an unexpected result is interpreted in clinical context.
Frequently Asked Questions
Is mIU/mL the same as IU/L for hCG?
Yes — they are identical (1:1). 1,500 mIU/mL equals 1,500 IU/L.
What is a normal hCG level?
It depends on the week — from 5–50 mIU/mL at 3 weeks to over 200,000 near weeks 9–12.
How fast should hCG rise?
It typically doubles every 48–72 hours in early pregnancy.
What hCG counts as not pregnant?
Below about 5 mIU/mL is generally negative.
References
- American Pregnancy Association — hCG levels in pregnancy: chart and ranges.
- Perinatology.com — Beta hCG doubling time calculator.
Conclusion
For hCG there is no conversion to do — mIU/mL and IU/L are the same number. What matters is the gestational week and, above all, how the level changes over time. Read your result against the ranges here, then interpret it with your healthcare provider.