Waiting between hCG blood tests might be the longest 48 hours you've ever experienced. This calculator helps you make sense of those numbers.

Enter your two beta hCG results, and you'll instantly see your doubling time, percentage change, and how your levels compare to typical ranges. Whether this is your first positive test, you're deep in the IVF monitoring phase, or you're trying not to catastrophize while refreshing your patient portal—this tool gives you real information instead of guesswork.

One thing to keep in mind: hCG trends are useful, but they're not the whole story. Your doctor looks at the complete picture. These numbers are one piece of it.

Human chorionic gonadotropin—hCG—is the hormone that makes a pregnancy test turn positive. Your body starts producing it shortly after a fertilized egg implants, and it rises rapidly over the first several weeks.

Here's what trips people up: a single hCG number doesn't tell you much on its own. Someone might have an hCG of 50 at 4 weeks and have a completely healthy pregnancy. Someone else might start at 300. Both are fine. What actually matters is whether your levels are rising appropriately over time—which is why doctors order two tests instead of one.

That rise follows a fairly predictable pattern in early pregnancy, and the "doubling time" is how we measure it.

Doubling time is exactly what it sounds like: how long it takes your hCG to double. Early on, that's typically every 2-3 days. But here's the part most websites skip—it's supposed to slow down as your levels get higher.

So if your hCG is 8,000 and it's taking 4 days to double? That's not a red flag. That's expected.

The ranges are guidelines, not laws. Healthy pregnancies have shown doubling times anywhere from 31 hours to over 96 hours. A number slightly outside these windows isn't automatically bad news.

Around 8-10 weeks, hCG levels peak and then actually start declining. This freaks people out when they first hear it, but it's completely normal—your placenta takes over at that point.

Step 1: Enter your first hCG level This is your baseline. Plug in the number from your first blood draw (in mIU/ml).

Step 2: Enter your second hCG level Your follow-up result. Most doctors schedule this 48-72 hours after the first.

Step 3: Enter the time between tests Pick days or hours, then enter how long you actually waited between blood draws. Be accurate here—it affects the math.

Step 4: Check your results You'll see:

• Doubling time — the main number everyone wants
• Percentage change — how much your hCG increased overall
• Daily increase rates — projected 24-hour and 48-hour growth

Your hCG is rising faster than average. Generally reassuring. Occasionally this can hint at twins, but don't start buying double strollers—only ultrasound confirms multiples.

This is the textbook range for early pregnancy. Your numbers are doing what they're supposed to do.

If your hCG is already above 1,200, this is totally normal—remember, higher levels = slower doubling. Even at lower levels, plenty of pregnancies in this range turn out fine. Your doctor will probably just want another test to watch the trend.

When hCG is still below 1,200 and doubling takes more than 4 days, that's worth a call to your provider. It doesn't guarantee something's wrong—maybe you ovulated later than you thought—but it needs a closer look. Possible concerns include early pregnancy loss or ectopic pregnancy.

If your second number is lower than your first, the calculator will show a negative trend. This usually means a pregnancy loss is happening. I'm sorry if you're seeing this. Please reach out to your provider—for medical guidance, yes, but also for support.

These ranges are notoriously wide. That's not a typo—it's just how pregnancy works.

Why the massive spread? Ovulation timing varies. Implantation timing varies. Individual hormone production varies. Two women both "5 weeks pregnant" can have wildly different hCG levels, and both pregnancies can be perfectly healthy.

This is why the trend between tests matters more than hitting some magic number.

You already know your exact timing, which is actually an advantage here. Most clinics schedule the first beta 9-14 days after transfer, depending on whether you had a day-3 or day-5 embryo.

Some rough benchmarks for day-5 blastocyst transfers:

• 10dp5dt: hCG above 50-100 is generally considered promising
• 12dp5dt: Ongoing pregnancies often show 100-400+ at this point

But your clinic has seen thousands of these results—follow their interpretation over any internet chart, including this one. They know your protocol, your history, and your specific situation.

Yes, higher hCG sometimes means twins. But there's so much overlap with singleton ranges that you genuinely cannot tell from bloodwork alone. I've seen singleton pregnancies with hCG through the roof and twin pregnancies with modest numbers. Ultrasound is the only way to know.

Ectopic pregnancies—where implantation happens outside the uterus, usually in a fallopian tube—sometimes show slower-rising or plateauing hCG. But some ectopics have totally normal-looking numbers at first.

Watch for symptoms: one-sided pain, shoulder pain, bleeding. If you have these plus a concerning hCG pattern, call your provider right away. Ectopic pregnancy needs medical treatment and can become an emergency if it ruptures.

Pick up the phone if:

• Doubling time is over 96 hours and your hCG is still below 1,200
• Your levels are dropping
• You have sharp abdominal pain, especially on one side
• You're bleeding heavily (light spotting is common and often fine—heavy bleeding isn't)
• You feel dizzy or faint
• You have pain in your shoulder tip (sounds weird, but it can signal internal bleeding)

Also valid: you just need someone to talk you through your results. Your medical team has fielded these calls hundreds of times. They'd rather hear from you than have you spiral alone.

Different labs: If you got your first test at one lab and your second at another, the numbers might not be perfectly comparable. Try to use the same lab for both draws.

Very early testing: If you're testing before your missed period, your levels might be too low to show a clear pattern yet. Sometimes you just need to wait a few more days.

Recent pregnancy loss: hCG can stay in your system for weeks after a miscarriage. If you're testing again soon after a loss, this can muddy the picture.

Trigger shots: If you used an hCG trigger shot for ovulation (common in fertility treatment), it takes time to clear your system. Your clinic will tell you when it's safe to test.

First test: 120 mIU/ml Second test (48 hours later): 290 mIU/ml Doubling time: 41 hours

Right in the sweet spot. This is what doctors hope to see.

First test: 4,500 mIU/ml Second test (72 hours later): 9,800 mIU/ml Doubling time: 78 hours

Looks slow compared to the "48-72 hour" rule—but at this hCG level, 78 hours is perfectly fine. This is reassuring.

First test (10dp5dt): 85 mIU/ml Second test (12dp5dt): 210 mIU/ml Doubling time: 39 hours

Strong rise after a frozen transfer. The clinic would keep monitoring, but this is a good start.

First test: 200 mIU/ml Second test (48 hours later): 310 mIU/ml Doubling time: 75 hours

A bit slower than typical for this range. Doesn't mean something's wrong—some healthy pregnancies look like this—but your provider will want another test to see what happens next.

First test: 500 mIU/ml Second test (48 hours later): 580 mIU/ml Doubling time: 168+ hours

That's barely rising. This needs follow-up—not panic, but a real conversation with your provider about next steps.

If you found this page at 2 AM because you're calculating and recalculating your numbers, trying to figure out if you should be worried—you're not the only one who's been there.

Early pregnancy, especially after loss or infertility, can feel like holding your breath for weeks. The math helps a little. Having information helps a little. But there's no calculation that can tell you exactly how this will turn out.

Here's what I'd say: if your numbers look good, try to let that be good news. If they're uncertain, let your doctor help you figure out what comes next instead of running every possible scenario in your head. And whatever happens, be gentle with yourself. You're doing the best you can with the information you have.

This calculator is for informational purposes and isn't a substitute for medical advice. Your healthcare provider can interpret your results in the context of your full medical history—which matters more than any online tool.