What Is an Evaporation Line on a Pregnancy Test?

If you’ve ever looked at a home pregnancy test and saw a faint line that doesn’t look like the normal result, you’re probably dealing with an evaporation line. It’s a ghostly streak that appears as the urine dries, not because of hormones but simply from the liquid evaporating.

How to Spot the Difference

The easiest way to tell if you have an evaporation line is by timing. A true positive or negative line shows up within the test’s recommended window – usually 3‑5 minutes after you finish testing. If you wait longer, say 10 minutes or more, any new faint line that appears is most likely an evaporation artifact.

Another clue is color. Real lines are generally darker and have a clear pink or blue shade (depending on the brand). Evaporation lines are usually very light, almost gray, and they lack the solid look of a true result.

Common Reasons It Happens

Evaporation lines appear because the urine dries unevenly on the test strip. Low humidity, high temperature, or using too much urine can all increase the chance of this ghost line forming.

Some people also see these faint marks when they use an expired test. The chemicals inside degrade over time and no longer react reliably, leaving behind a weak visual cue as the liquid evaporates.

Steps to Get a Clear Result

First, read your test within the window stated on the package – no sooner than 1 minute and definitely not later than the maximum time. If you’re unsure, set a timer so you don’t lose track.

Second, use first‑morning urine if possible. It’s more concentrated with hCG, which gives the test a stronger reaction and reduces confusion from faint lines.

Third, keep your testing area at a comfortable room temperature. Extreme heat can cause rapid drying, making evaporation lines more likely.

What to Do If You See an Evaporation Line

If you spot a light line after the reading window, treat it as “no result.” The safest move is to retest with a fresh kit, following the timing guidelines exactly.

Should you still get unclear outcomes, consider visiting a pharmacy or doctor for a blood test. Blood tests detect pregnancy hormones earlier and aren’t affected by evaporation artifacts.

When to Seek Professional Help

If you’ve missed periods, experience early pregnancy symptoms, and keep getting ambiguous lines, it’s time to talk to a healthcare professional. They can confirm pregnancy and rule out any underlying issues.

Remember, an evaporation line is just a drying effect – it doesn’t mean anything medically. By reading your test correctly and following the simple tips above, you’ll avoid most of the confusion and get reliable answers.