Should I Be Testing with OPKs Twice a Day?

Karine Sabourin
Jul 22
2 min read

You’re scrolling Instagram.

You see a TTC girlie with a photo of her entire week’s worth of OPK test strips — labeled, dated, possibly color-coded.

She’s testing twice, sometimes three times a day — and naturally, you’re wondering:

“Wait… am I supposed to be doing that too?”

Let’s break it down — no shame, no pee stick panic — just the facts on when testing once is enough, and when twice a day might be worth it.

What OPKs Actually Measure

OPKs detect a rise in luteinizing hormone (LH) — the hormone that spikes about 24–36 hours before ovulation.

Catching that surge helps you time intercourse during your most fertile window.

But for some people, that surge doesn’t last very long.

If your LH peaks and fades within 12–18 hours (totally normal), testing just once a day could mean you miss it.

Can You Really Miss Your Surge?

Yep — especially if:

Your surge is short or subtle
You’re testing too early or too late in your cycle
You’re testing in the morning (LH tends to surge later in the day)
Your OPK isn’t sensitive enough

Also? That “99% accuracy” on the box?

It means the test is accurate once it’s positive — not that it will catch every surge.

When Testing Once a Day is Totally Fine

If you’ve caught your LH surge before by testing once a day — especially in the late morning or early evening — great! No need to change what’s working.

One test a day is totally fine if:

Your cycles are regular
You’re seeing a clear progression
Your timing has been consistent and reliable

When It’s Worth Testing Twice a Day

If you’ve ever thought:

“Why do my lines look darker, then lighter again?”
“I think I missed my surge…”
“I never get a positive OPK…”

Then yes, it might be worth testing twice a day, just for a few cycles.

This can help you:

Catch short or subtle surges
Confirm patterns if your cycles are irregular
Stop wondering if you’re just missing it altogether

How to Test Twice a Day (Without Losing Your Mind)

Start when you first notice fertile cervical fluid (slippery, stretchy, egg-white vibes — that’s estrogen on the rise, and LH usually follows)
Test once in late morning and once again in early evening
Keep testing through the surge, even after a positive — because if your body surges but doesn’t ovulate, there could be a second surge coming later