I Tried Clue vs Flo vs Glow and There’s A Clear Best Free Period Tracker

Update 10/23/23: This post has been updated to reflect the current status of Clue vs Flo vs Glow’s free versions. We have also included information about privacy policies for each of the best period trackers.

Few things are more important for females interested in human life extension than period tracking. It’s so critical that just about any time you go to the doctor’s office, you’re expected to report in: when was the first day of your last period? For plenty of women, these doctors might as well ask what you had for lunch two Thursdays ago. Unless it’s written down somewhere, your memory has already let it go.

If you’re interested in what menstruation has to do with how long someone lives, check out our previous full article on female longevity.

Period tracking is important though. It’s one of the best tools for taking charge of your fertility, getting data on your gynecological health, and staying aware of how close you are to peri-menopause (which can start up to ten years before menopause!), or menopause itself. Remember, there’s no time when people who menstruate aren’t at some point in their cycle, and knowing what your hormones are doing can provide insight into your day-to-day health.

The best free period tracker

Up until recently, I’d been using my Fitbit’s menstrual tracking app to monitor my cycles. It has some serious downfalls though—for example, I couldn’t pause cycles when I became pregnant, there is no way to monitor trends over time, and in spite of being linked to my cardio tracker and strength training apps of choice, there is no automated way of matching up my recorded biometrics. Kind of a bummer. So I went onto both the Apple and Play Stores to see what menstruation apps were available.

And holy bleeding Batman, there were over 80 cycle apps to review. 

Hence began my search for the top free period tracker. Over the past few weeks, I downloaded and tested the lion’s share of these apps, whittling down the daunting list of apps with the following rules:

• Must be simultaneously available both on iOS and Android. 
• Must receive at least a 4.0 rating in both app stores with over 1,000 reviews. 
• Must have been updated in the past six months. 
• Must be specifically made to track menstruation, as opposed to related topics like fertility tracking, menopause, or PMDD.
• Must provide trends analyses.
• Must provide a usable free version. 
• Must have an explicit data privacy policy.

Clue vs Flo vs Glow 

By the time I got down to the top six period tracking apps (Clue, Eve by Glow, Flo, Glow, Ovia, and Period Tracker Period Calendar, if you must know), I noticed a trend in how these apps marketed themselves and how they referred to each other: Clue, Flo, and Glow appeared to be the benchmark brands, and other options were compared to those three options. 

So I figured, hey, why not download those three and compare them directly? So I did.

And one stood out substantially.

Clue Review

iOS Rating: 4.8; 346,600 reviews

Android Rating: 4.4; 1,220,000 reviews

Paid version: $30 for 12 months

Android | iOS

Let me start by saying that if you’re a spanner, you like health data, and you like a good “why” behind your body’s monthly fluctuations, then Clue is a good option. When you plug in your data, Clue allows you to visualize your cycle on a calendar and on a circle-looking thing (see the screenshot). 

The free version is excellent: it provides you with an overview of which symptoms you experienced over the course of your cycle and in what quantity, how long your fertility window lasts, and lets you know if something is amiss with your predicted cycle. As a free user, I don’t feel overwhelmed with the nudges to upgrade to its paid plan. That said, the app provides a paid option to switch over to “pregnancy mode” if applicable, complete with a calculator to estimate when the baby is due and what to expect week-to-week. 

I do like that I can manually track a whole bunch of additional variables with Clue, from stool consistency to vaginal fluids to food cravings. Each variable comes with an excellent research-backed writeup on what each variable has to do with the menstrual cycle. Unfortunately, the end result still puts a lot of pressure on the end-user to make sense of the data. For example, it’s one thing to see a graph of what days your hair is “oily,” “dry,” “good,” or “bad” and align it with the menstrual cycle, and it’s another to make that data actionable. Sure, oily hair might align with my follicular phase, but I don’t know if that’s important to know or track for my healthspan or lifespan. 

There were a few features I really would have liked to see with Clue, with the most important being integration with third-party apps.

I logged into Clue for iOS using my husband’s phone and didn’t notice any differences in the app experience.

Data Privacy

Clue provides some information to third parties and is explicit in how they do so, and will request data deletion on your behalf if you stop using the app. They do allow you to delete your data following a 30-day retention period. Some data is anonymized and sent to third parties. Clue explicitly states that they will not share your data with the U.S. government. Clue’s data privacy policies are the most robust of the apps reviewed in this article

Flo Review

iOS Rating: 4.8; 1,200,000 reviews

Android Rating: 4.6; 3,210,000 reviews 

Paid version: $59.99 for 12 months

Android | iOS

Let me tell you about my frustration with Flo. 

At first glance, the app appears to be both too simple and asks too much of the user initially. For example, in order to get started Flo inquires when your last period was and how long your cycles typically last. But this is the kind of information you should glean from a top free period tracking app, and not necessarily know before installing one. 

Using that data, Flo automatically filled out my period history and my predicted periods… which would be great if I were 100% regular 100% of the time (and, like most females, I’m not). So I tediously went back and fixed my past cycles, noting that changing the date for the cycle itself is divorced from logging symptoms like cramping, discharge, or disease. 

But lo, there was something that made Flo entirely enticing, and that’s its ability to sync with third-parties. Finally. Android users can sync with Google Fit and Fitbit. iOS users can sync with The Health App and Fitbit. So I tried to sync it with my Fitbit, anticipating all the new information I could learn about my cycle and other biometrics.  

While flipping between laptop, Android, and iOS, I was bombarded with notifications. Rate our app! Get premium! One-dollar 30-day trial! I think I would choose an extra day of pre-menstrual cramps before my next period over having to navigate through that cascade of popups and notifications again.

My tone may have been different if I could have gotten my nuanced Fitbit data to sync, but overall I found the app’s features to be paywalled or lacking. My feed filled with Flo’s articles, all of which were basic (“Drink Water and Make it a Habit”) or only tangentially relevant (“Spontaneous Orgasm: Normal or Not?”), and users have to pay to access that content.

To be fair, there were a few things that I liked about Flo. The app provides a nice overview for each day of the cycle, with an Instagram-stories-like slideshow about what’s normal for discharge, mood changes, and chance of pregnancy. You can track a variety of variables with more nuance than Clue, like if you’re sick or are feeling frisky, and there’s more of an emphasis on vaginal discharge. 

There’s also a “secret chats” feature, where users can ask potentially uncomfortable questions of other users in a moderated forum. I’m lukewarm on the idea because I think people who menstruate are more willing to talk about their health than they’re given credit for, but appreciate the option for people who would take advantage of it. 

Finally, and unfortunately, I found Flo to fall into the troubling marketing trend of all-apps-for-women-must-be-weight-loss-apps. When setting up your profile, Flo asks you about your fitness goals, and most of them point towards weight loss. Half of your “Lifestyle Settings” are about your “target weight,” caloric intake, and BMI. Before logging relevant menstruation markers like spotting, vaginal discharge, or cramps, Flo asks daily about your weight. 

This criticism is not to say that weight-related biomarkers aren’t important, but it seems out of place for a “best” free menstrual health app—you’d think period tracking would take priority. 

For users still considering using this app, the iOS version offers a substantially smoother experience over Android. 

Would I recommend Flo? Not in good faith, unfortunately.

Data privacy

Flo came under fire in 2021 when they shared their users’ health data with Facebook, Google, and other third parties. Since then, they’ve invested in an ISO 27001 certification (a medical grade privacy certification) and claim to regularly get third-party privacy audits. In spite of all this, Flo still shares its users’ information with Appsflyer, which in turn shares advertising information with third parties like Pinterest and Snap.

Glow Ovulation & Period Tracker Review 

iOS Rating: 4.7; 66,400reviews

Android Rating: 4.37; 70,800 reviews

Paid version: $59.99 for 12 months

Android | iOS

I don’t think it’s fully fair to include Glow in this review in part because, unlike Clue and Flo, Glow offers so little in their free version. The app offers an ovulation tracker and fertility predictor with some cool population-based statistics, but all other data patterns operate behind a paywall. Given that, there’s not much that differentiates Glow from other top but less-popular period tracking apps like Fertility Friend or Ovia. 

Something I appreciate about Glow is the variability in logging physical symptoms. Glow offers the ability to not only check off period pains like diarrhea or fatigue but rate their severity on a three-point scale. Tracking these observational trends could be helpful in detecting period variability (or finally admitting defeat and accepting what’s “normal” for your body) as you approach menopause.

Glow offers an integration with MyFitnessPal and Google Fit (on Android) and Apple Health (on iOS). I used Fit2Fit to sync my Fitbit data with Google Fit to see if I could get anything more actionable from the app, but the sync really didn’t change much. I couldn’t find any new data on the app after doing so; it didn’t even show up. My bet is that any difference it would have made is happening behind a paywall. 

The only other piece worth commenting on is the community aspect of Glow. Glow syncs (haha) its users with other people on a similar menstruation schedule, allowing them to discuss their period cycles throughout. The app also has forums and articles based on larger interests, like “Skincare Product Reviews,” “Love,” and “Period Products Talk.” The most active groups appear to be those related to conception, pregnancy, and lesbian relationships.

In other words, Glow isn’t a bad app. It’s just not a great app. Spanners wanting to spend money on menstruation data may want to consider Glow’s premium plan, but the free period tracker really doesn’t offer much otherwise. 

There were no significant differences between the Android and iOS versions of Glow.

Data Privacy

Glow has a hefty privacy policy, partially, I imagine, because they got in trouble with California in 2020 for privacy and security violations (though they did not admit any wrongdoing). They explicitly note that they will comply with U.S. law enforcement if asked for individual private health information.

Clue vs Flo vs Glow: The best free period tracker for longevity

Flo and Glow simply don’t have much to offer. In spite of being two of the three most popular menstrual health apps, I found their insights only mildly useful. 

Clue isn’t a perfect app, but I believe that their science-based approach to menstruation matches up more to what a spanner would be looking for. It is, definitively, the top free period tracker. Anyone who’s willing to engage in every single one of their tracking options—from skin to body temperature variations—would get a better baseline for their overall health than, say, using a pedometer. The trouble would simply be that full commitment. 

With all that said, Clue isn’t perfect for people interested in life extension

I won’t dwell on my inability to sync my other apps to Clue, but I will give pause to a few missing features. In particular, while I can manually add in whether or not I took a supplement to Clue’s daily tracking calendar, I wish I could get more detailed correlation data from it. For example, if I’m taking Vitamin B3 (Niacin), am I more likely to flush during my luteal phase? Is evening primrose oil actually helping with tender breasts over time? Are my periods getting closer together, flagging the beginning of menopause? How much do the severity of my cramps change from period-to-period? If something is changing, I should know about it. 

The emphasis of Clue—along with Flo and Glow—is not on life extension. It’s clearly made for heterosexual women primarily interested in getting pregnant (or avoiding pregnancy altogether). Like so much of the medical field, women’s health is distilled to reproductive health, ignoring the fact that the whole cycle changes female biochemistry daily. The intersection of menstruation and variables like nutrition, sleep, and exercise could unlock a whole field of otherwise ignored quantified self. Women shouldn’t have such a hard time tracking that data, but these period trackers just aren’t made for it. 

Clue’s myopic approach can be mitigated with diligent tracking on behalf of the spanner and using consolidation apps and spreadsheets to sync all the data. But it’s all a lot of work. 

Tell me I’m wrong. 

Do you use Flo or Glow and disagree? Or have you had difficulty with Clue? Should this article have prioritized things differently?

Tell me about how you track your period and use that data for life extension in the comments below!

Rachel Burger

By day, I am a problem solver, writer, and the co-founder of Longevity Advice. I’m best known for writing about technology and have been featured in Forbes, The Hill, and TechRepublic. When the batteries are powered down and the suit comes off, I’m an enthusiastic hiker, runner, and Rocket League competitor and enjoy discussing minimalism, Studio Ghibli, and Icelandic sheepdogs.