Beta hCG level calculator

In early pregnancy, hCG typically doubles about every two days, but a rise of at least 53% over 48 hours can still be consistent with a healthy pregnancy. Enter two or more results and the dates they were drawn, and the calculator above shows your doubling time and how your rise compares. Haven’t tested yet? My Implantation & DPO calculator shows when implantation most often happens and the day your period is due: the first day a home pregnancy test is worth taking.

If you’ve just entered your results, it’s tempting to focus on whether the output looks “good.” I’d rather you understand what changed between blood draws than spend the afternoon comparing your result with someone else’s screenshot.

I’m Dr. Lucky Sekhon, a double board-certified reproductive endocrinologist and infertility specialist in New York City and author of The Lucky Egg. I went through IVF myself, so I know that understanding the science and feeling reassured are not always the same thing. For what a first beta after IVF means, head to Understanding Beta hCG Levels After IVF.

Follow the trend, not the number.

How is hCG doubling time calculated?

Doubling time estimates how long your hCG would take to double at the pace measured between the blood draws you entered. It describes that interval, rather than predicting exactly what your next result will be.

Doubling time in hours = hours between draws × ln(2) ÷ ln(later hCG ÷ earlier hCG).

“Ln” means natural logarithm; the calculator handles that part for you. The important inputs are the earlier level, the later level and the time separating them.

For example, a rise from 120 to 260 mIU/mL over 48 hours gives a doubling time of about 43 hours and a 117% rise. A shorter doubling time means a faster increase; a longer one means a slower increase.

Use the blood-draw dates, not the dates your results appeared in the portal. Match each level to its actual draw and check the order before reading the output. A portal delay does not count as extra time for your hCG to rise.

How much should hCG rise in 48 hours?

Doubling is reassuring, but it is not the only rise seen in viable pregnancies. In Barnhart’s 2004 study, the median rise over two days was 124%, while the slowest rise was 53%. That median is not a target you have to hit.

Your starting level matters, too: the minimum expected rise becomes slower as the initial hCG increases.

Read the row that matches your earlier result, not your latest one. That is the starting point for the interval you are checking, and it explains why someone with a higher beta may have a slower expected rise.

These are reference points, not viability cutoffs: falling below them calls for assessment, while exceeding them does not guarantee an ongoing pregnancy.

These studies followed women who came in with pain or bleeding, not IVF patients specifically; applying them after a transfer is standard clinical practice.

The calculator above adjusts for draws that aren’t exactly 48 hours apart, so you don’t need to force your results into a two-day comparison. Enter the actual draw dates and let it account for the interval.

What does a slow-rising, flat or falling hCG mean?

Think of hCG like a plane’s flight path. A dot on the map gives you its position; watching it move tells you the direction and pace. That is what I want you to focus on when you look at the calculator’s result.

A slower-than-doubling rise does not automatically mean miscarriage. A plateau or drop while hCG should still be rising is more concerning, as I explain in Understanding Beta hCG Levels After IVF. If the level is flat or falling, there is no useful rising-curve doubling time to interpret.

My clinical opinion: hCG alone cannot tell us where a pregnancy implanted. If an ultrasound has not yet located it—a pregnancy of unknown location—I want repeat blood tests and scans to clarify what is happening and assess the possibility of an ectopic pregnancy.

Ask your clinic what the next test is intended to clarify and when it should happen. Having a follow-up plan is more useful than repeatedly recalculating the same results.

For the context after genetic testing, read why miscarriages still happen after transferring a PGT-normal embryo.

Keep taking your medications as prescribed unless your clinic tells you otherwise.

When does hCG stop doubling?

The pace does not stay the same throughout pregnancy. The rise slows as levels climb, and hCG generally peaks around 10 weeks before falling.

By then, ultrasound has taken over as the more useful measure of progress. Doubling time stops being useful, and continuing to compare later results with an early-pregnancy curve can create unnecessary worry.

That expected later decline is different from a drop during the early rising phase. The question shifts from “How fast is the hormone rising?” to “What does the scan show?”

Follow the trend with your clinic, and let each new blood test or scan add information. When you’re ready to look ahead, the IVF Due Date Calculator helps put future milestones on your calendar.

This is not a substitute for medical advice, and a single value cannot predict how a pregnancy will go. Speak to your RE or OB to confirm everything shown here.