What is the Evaporation Line?

Team Peanutabout 2 months ago4 min read

Whether you’re TTC or trying to avoid getting pregnant, pregnancy tests are some of the hardest tests you ever take in life.

Throw the evaporation line into the mix, and things get even trickier.

Evaporation Line

So what is the evaporation line? What causes it? And what should you do if you think you’ve got one?

Let’s take a look.

Evaporation line on pregnancy test FAQs

First, a quick spin around how home pregnancy tests work.

Basically, they’re on the hunt for a hormone called hCG that’s released when implantation happens.

If your test is able to find a sufficient amount of hCG in your pee, you get a positive result. If not, you get a negative result.

So that all of this detective work can happen, you either have to pee on the test itself or pee into a cup.

If you pee into a cup, you either use a dropper to get the liquid onto the test or dip your test into the cup.

And then you have to read the results.

The way these show up depends on the display setup of the pregnancy test you’re using.

The more old-school tests show one line if you’re negative and two if you’re positive.

Digital pregnancy tests, although on the lookout for the very same hCG hormone, display the results a little differently.

They simply say the words PREGNANT or NOT PREGNANT on the display screen, taking away at least some of the guesswork.

If you’re using the version that shows one line for negative and two for positive, there’s a chance you could get an evaporation line which can confuse your results.

What is an evaporation line?

An evaporation line (or evap line) on a pregnancy test can look like a very faint, discolored positive result—but actually isn’t one.

The line appears only after your pee has evaporated (hence the name) and may mean that too much time has passed between taking the test and checking your result.

But a time-lapse isn’t the only reason for the appearance of the evap line.

It could be that the test got wet.

Or that it just happened.

(Read: don’t blame yourself. Breathe. This is stressful enough.)

How common is an evaporation line?

Evap lines are common and can be both disheartening and confusing.

If you’re at all uncertain about your result, take another test.

So that you can get as accurate a result as possible, it’s best to wait until after your next expected period.

This will allow your hCG levels to get above 25 mIU/mL, the levels necessary for a positive result.

False-positive pregnancy test results are also possible for several reasons, one of which is a very early pregnancy loss.

If you’ve just been pregnant or are taking fertility meds, you might also get a false positive.

What color is an evaporation line on a pregnancy test?

Evaporation line vs faint positive—how do you tell which is which?

The key difference is that an evaporation line is colorless (which may appear as a faded gray on most tests).

This is an important distinction because if your test is positive, the line that tells you it’s a positive result will appear in the same spot as the evap line—but will have some color to it.

Positive lines are also usually a little thicker than an evap line.

(BTW, if you need help, there’s a whole Peanut community dedicated to this very topic)

How long does an evaporation line last?

Evap lines usually only develop after the window of time for reading the results—and won’t appear every time you take a test.

One way to decrease the chances of the kind of confusion evap lines can cause is to read your results in the time that it states in the instructions.

Sometimes this is two minutes, sometimes it’s up to 10.

And if you need help, reach out to your healthcare provider.

This journey can be pretty isolating. It’s more than okay to ask for support.

Good luck. 💖

You might also be interested in:
Negative Pregnancy Test But Feeling Pregnant? What’s Going On?
Everything You Need to Know About a False Negative Pregnancy Test
When is the Best Time to Take a Pregnancy Test?
Pregnancy Symptoms but Negative Test