hCG doubling calculator

Is my hCG rising normally?

Enter your hCG blood test results and the dates you took them. We work out how fast the level is doubling.

Try an example:

First hCG test

Result

mIU/mL

Date

Time optional

Second hCG test

Result

mIU/mL

Date

Time optional

Tests are 48 hours apart.

These are example numbers. Replace them with yours, then press Calculate.

Example answer

44.8hours to double

Expected rise

A rise at this rate is reassuring in early pregnancy.

Under 48 h48–72 h72–96 hSlower or falling

This is a guide, not a diagnosis. Share the result with your doctor.

Your hCG rise, drawn out

Your results, against a level that doubles every 48 hours.

Your resultsIf it doubled every 48 hours

See the numbers

Where your level sits

Your latest result on the hCG scale.

The scale grows by ×10 at each step, because hCG climbs so fast in early pregnancy.

What to do next

Your result is highlighted. Your own clinic's advice always comes first.

Your resultExpected rise

Keep following your clinic's plan. Don't stop any medicines unless your clinic tells you to. Your clinic will usually book a first scan once your hCG is high enough to see the pregnancy.

Your resultBorderline

Share both results with your clinic. They will usually ask for another test about 48 hours later. One borderline result on its own does not tell the whole story.

Your resultSlower than expected

Call your clinic and give them both numbers. They may repeat the test and arrange an early scan to check where the pregnancy is.

Your resultTalk to your doctor

Contact your clinic today.

Get urgent medical help if you have severe pain in your tummy or shoulder tip, heavy bleeding, or feel faint or dizzy. Call 112 or 108. Warning signs

How this calculator works

Three steps. You need two blood test results.

Step 1
First blood test
Your clinic measures your hCG level from a blood sample.
Step 2
Wait about 48 hours
Then you have a second test. Enter both dates and we work out the hours.
Step 3
See how fast it doubles
We turn the change into one number: the hours it takes to double.

The sum, with your numbers

About this calculator

?What it tells you

How quickly your hCG level is going up, shown as the hours it takes to double. It compares that against reference points from published studies.

✓Who it is for

Anyone with two hCG blood test results in early pregnancy, including after IVF, IUI or a natural conception.

iWhat you need

Your first hCG result in mIU/mL
Your second hCG result
The date of each test, and the time if you know it

!What it cannot tell you

Whether the pregnancy is in the right place. Only a scan shows that.
Whether it is twins.
Anything useful from one result on its own.

Tips for an accurate result

Small things that change the answer.

1Use the same lab each timeDifferent labs can measure hCG in slightly different ways. Comparing results from two labs can make the rise look faster or slower than it is.
2mIU/mL and IU/L are the sameIf your report says IU/L, type the number in as it is. No conversion needed.
3Use blood test numbers onlyHome pregnancy tests only show yes or no. This calculator needs the number from a blood test report.
4Testing too soon after the trigger shotIf your trigger injection contained hCG, it can stay in your blood for up to about two weeks. A test taken too early may pick up the injection, not a pregnancy. Follow your clinic's test date.
5Add the time of each test if you know itA few hours makes a difference. 100 to 210 over 48 hours doubles every 44.8 hours. The same rise over 44 hours doubles every 41.1 hours.
6Later results rise more slowlyOnce hCG passes about 1,200 mIU/mL, the doubling time naturally gets longer. Compare like with like, not your fifth test with your first.

What this means

One hCG number on its own tells you very little. What matters is how fast it changes between two tests taken about 48 hours apart.

In early pregnancy, hCG usually rises by at least 35 to 53 percent in 48 hours. The rise slows down as the level gets higher, so a slower doubling later on is normal. A scan is usually useful once hCG is above about 1,500 to 2,000 mIU/mL.

Common questions

Is one hCG number useful on its own?

Very little. The normal range at any point in early pregnancy is extremely wide. The change between two tests taken 48 hours apart carries nearly all the information.

My doubling time is slow. Does that mean a miscarriage?

Not necessarily. Slow rises occur in pregnancies that continue normally, and the rate naturally slows as levels climb. It does need clinical review, because ectopic pregnancy also presents this way.

Can hCG tell me if it is twins?

No. Levels overlap far too much between singleton and multiple pregnancies for any threshold to be meaningful. Ultrasound answers this.

In an emergency

If you have any of the warning signs listed here, don't wait for a test result or a calculator. Get help now.

112All emergencies, anywhere in India 108Ambulance

Also call your IVF clinic. Most clinics give an emergency number on your treatment or discharge sheet. Save it in your phone now, before you need it.