Inito is a smartphone-connected fertility monitor that measures four reproductive hormones from a single urine test strip, then uses your phone’s camera and an image-processing algorithm to give you actual hormone levels rather than a simple positive or negative result. It tracks estrogen, LH, PdG (a marker of progesterone), and FSH across your cycle to identify up to six fertile days and confirm whether ovulation actually occurred.
The Hardware: A Clip, a Strip, and Your Phone
The Inito device is a small reader that attaches to your smartphone. You dip a test strip in urine, insert it into the reader, and open the Inito app. Your phone’s camera captures an image of the strip, and the app’s software analyzes the color changes on it to calculate the concentration of each hormone present.
The system converts those color intensities into optical density values, which map to specific hormone concentrations using a calibration curve generated for each batch of test strips. Because different phones have different cameras, the software uses a multi-scale algorithm to account for variations in resolution and aspect ratio, so results stay consistent whether you’re using a newer or older device.
Four Hormones From One Strip
Most standard ovulation tests only detect LH, the hormone that surges roughly 24 to 36 hours before ovulation. Inito measures four hormones simultaneously, each providing a different piece of the fertility puzzle:
- E3G (estrone-3-glucuronide): The urinary form of estrogen. It rises in the days leading up to ovulation as a follicle matures in the ovary. Tracking this rise is what extends the detectable fertile window from two days to as many as six.
- LH (luteinizing hormone): The surge that triggers the egg’s release. Inito shows you the actual level rather than just a threshold line, which can be easier to interpret than eyeballing whether a test line is “as dark as” a control line.
- PdG (pregnanediol glucuronide): The urinary metabolite of progesterone. Progesterone rises after ovulation, so PdG is what Inito uses to confirm that ovulation has taken place, not just that LH surged.
- FSH (follicle-stimulating hormone): Helps characterize overall cycle health and can flag issues like a shortened luteal phase.
Quantitative vs. Threshold-Based Testing
Standard ovulation predictor kits (OPKs) work on a threshold model: either your LH is above a cutoff and the test reads positive, or it isn’t. That binary result can be hard to interpret. Some people have LH surges that are subtle or short-lived, and judging whether a test line matches the control line is genuinely difficult by eye. In one study comparing fertility monitoring methods, participants noted that getting a numeric value made interpretation “so much easier” than visual comparison of line darkness.
Inito takes a different approach by giving you the actual concentration of each hormone. The app charts these values over time, building a personalized hormone curve for your cycle. This means you can see estrogen gradually climbing days before your LH surge, watch the surge itself, and then verify progesterone’s rise afterward. That full picture is something a standard LH strip simply can’t provide.
How It Identifies Your Fertile Window
The app identifies fertile days primarily through the combination of rising E3G and the LH surge. Because estrogen begins climbing several days before ovulation, tracking E3G alongside LH expands the detectable fertile window to roughly six days. Validation research found that a six-day fertile window correlated best with the occurrence of an ovulatory cycle, compared to shorter or longer estimates.
The algorithm also establishes a personal baseline for each hormone. For PdG, it calculates your average level before the LH surge, then compares it to your PdG levels two to three days after the surge. A meaningful rise above that baseline is what confirms ovulation actually happened. This distinction matters because it’s possible to get an LH surge without releasing an egg, a situation standard OPKs wouldn’t catch.
How Closely It Matches Blood Tests
A peer-reviewed validation study published in Scientific Reports compared Inito’s urinary hormone readings against standard blood tests. The correlations were strong: urinary PdG matched serum progesterone with an R² of 0.95, urinary E3G matched serum estradiol at 0.96, and urinary LH matched serum LH at 0.98. When the researchers used these correlations to predict serum values from urine samples in a separate set of unknown samples, accuracy held up well, with correlations of 0.92 to 0.94. In practical terms, the at-home urine readings tracked very closely with what a blood draw at a lab would show.
What Testing Looks Like Day to Day
You test with first morning urine, which tends to have the most concentrated hormone levels. The app tells you which days to test based on your cycle length and history. Early in your cycle, testing establishes baseline hormone levels. As you approach your expected fertile window, the app prompts more frequent testing to catch the estrogen rise and LH surge. After the surge, you’ll test again a few days later so Inito can check for the PdG rise that confirms ovulation.
Each test takes a few minutes. You dip the strip, wait for it to develop, insert it into the reader, and let the app scan it. Results appear as numeric values on a chart that builds over the course of your cycle, giving you a visual timeline of all four hormones. Over multiple cycles, this data can reveal patterns, like whether your luteal phase is consistently short or your progesterone rise is weaker than expected, information that can be useful to share with a reproductive health provider if you’re having trouble conceiving.
Who Benefits Most
Inito is designed for people trying to conceive who want more information than a basic OPK provides. It’s particularly useful if you have irregular cycles, since the quantitative hormone tracking adapts to your individual pattern rather than relying on textbook cycle-day assumptions. It’s also valuable if you’ve been timing intercourse around positive OPKs without success, because confirming ovulation with PdG can reveal whether the egg is actually being released. For people whose cycles are regular and predictable, a standard LH strip may be all that’s needed, but the added hormones give a fuller diagnostic picture that can surface subtle issues earlier.