The best smart rings for women, ranked on fit, cycle features and fees

What “for women” should actually mean

None of the rings on this list is a separate women's model. Each brand sells one ring in a range of sizes and finishes, and “smart rings for women” mostly means the same hardware in a smaller size or a rose-gold finish. That's fine. What decides whether a ring works for you sits underneath, and it comes down to four things:

• How small the size range goes. Two rings start at 5 and one at 4. Everything else starts at 6.
• How much battery a small ring keeps. Smaller rings get less battery, and two brands say so in their own figures.
• What the cycle features do, and whether they cost extra. One ring includes cycle predictions with no fee, one sells them as an optional yearly add-on, and one brand puts them behind a membership.
• Whether you'll pay to see your own data at all. This site is written for the buyer who won't, so the fee carries the most weight in our ranking.

Weight and thickness matter for a ring you sleep in, but most brands don't publish them. Where we have a figure, it's below; where we don't, we say so rather than guess.

The smallest sizes, brand by brand

If you wear a small ring size, the list narrows fast. The Oura Ring 4 is the only ring here that starts at size 4. The Ultrahuman Ring PRO and Samsung Galaxy Ring start at 5. Every RingConn ring, and Oura's newer Ring 5, starts at 6.

Those numbers aren't comparable across brands. Oura says its whole sizes “differ slightly from standard US ring sizes,” RingConn says Gen 3 sizes differ “from other RingConn rings, standard rings and other smart ring brands,” and Samsung says its sizes are “slightly different from that of regular rings.” A 5 at Samsung isn't guaranteed to match a 5 anywhere else. Every brand here offers a sizing kit, so use the one for the ring you're actually buying. Our guide to smart rings in large and small sizes goes size by size.

Small rings, smaller batteries

There's a catch at the small end that rarely makes the headline. Oura's product safety page lists a “15mAh (US6) - 22mAh (US13)” battery, so a size 6 carries about two-thirds of the capacity of a size 13 (Oura Support). Samsung rates the Galaxy Ring at up to 7 days only for sizes 12 and 13, and up to 6 days for smaller sizes. Oura qualifies its Ring 5 claim of 6-9 days with “depending on ring size and usage.” RingConn and Ultrahuman quote one battery figure for every size on the pages we checked. If you wear a small size, plan around the low end of any range; our smart ring battery life guide reads each claim with its fine print.

Cycle tracking: what each ring does and what it costs

This is where the fee question gets personal. Here's what each brand lists, and what you pay for it:

• RingConn Gen 3: “Women's Full-Cycle Predictions” is one of its headline features, and RingConn charges no subscription for anything; The Gadgeteer found “no locked tier, no upsell screen anywhere in the app.” The cycle-prediction feature we could source is Gen 3's. RingConn describes the Gen 2 Air more generally, as covering “key health tracking features.”
• Oura: Cycle Insights. Oura says it “uses temperature trends to unlock more accurate insights about your menstrual cycle.” Cycle Insights aren't on Oura's list of what you keep without a membership (three daily scores, battery, profile, settings and Explore content), so plan on $5.99 a month or $69.99 a year.
• Ultrahuman Ring PRO: no required fee, but Cycle & Ovulation Pro is an optional PowerPlug at $39/year on Ultrahuman's Ring PRO buy page.
• Samsung Galaxy Ring: Samsung's US page promises “regular readings on skin temperature changes while you sleep.” The ring page we checked doesn't name a cycle feature, so we don't credit it with one.

Our guide to smart ring temperature tracking explains what finger temperature can and can't tell you, and what the studies behind it measured.

What each pick costs to own

Only the two Oura rings require a fee. On the annual plan it adds $209.97 over three years, or $349.95 over five. If Cycle Insights are the reason you'd buy Oura, that's what they cost on top of the ring. On the no-fee side, Ultrahuman's Cycle & Ovulation Pro is the one optional cycle charge. The full brand-by-brand picture is in what smart rings really cost over three years.

How we ranked them

We start from each ring's score on our published rubric (cost of ownership 30%, evidence of accuracy 25%, battery 15%, sizing and fit 10%, data ownership 10%, phone support 10%; the reasoning is on our methodology page), then order the list by what this page is about: the small end of the size range and cycle features with no required fee. Everything comes from brand pages, named reviewers and studies, linked in the sources below.

That changes one placement. The RingConn Gen 2 Air scores 9.4 overall, higher than the three rings ranked just above it, but it starts at size 6 and the cycle feature we could source is Gen 3's, so it sits fifth. The RingConn Gen 2 and Circular Ring 2 aren't on this list for the same reason: neither adds a smaller size or a sourced cycle feature over the picks here. Both appear in our best smart rings without a subscription, and every ring's specs sit side by side in the smart ring comparison chart.

The picks in context

1. RingConn Gen 3: best for women

The Gen 3 is the only ring on this list with a named cycle feature and no fee of any kind. RingConn lists Women's Full-Cycle Predictions alongside Sleep Apnea Pattern Insights, Vascular Health Insights and Smart Vibration Alerts. RingConn claims up to 14 days a charge (11-14 on its features page) and 150+ days in total with the charging case; The Gadgeteer's reviewer got about 10 days with vibration alerts on. It's titanium, 2.3 mm at its thinnest per The Gadgeteer, and rated IP68 and 10ATM. RingConn sends a complimentary sizing kit and ships the ring once you confirm your size. The limits: sizes start at 6, no study has tested Gen 3 itself, and it showed “Out of stock” on RingConn's own store when we checked, though Amazon listed it. Our RingConn Gen 3 review covers the rest.

2. Ultrahuman Ring PRO: size 5 and an optional cycle add-on

Ultrahuman's ring starts a size smaller than RingConn's, at 5, runs to 14 with no half sizes, and comes with a free sizing kit that's yours to keep. It claims the longest battery we found, up to 15 days and 45 with the included PRO Charging Case, and requires no fee: Ultrahuman says there are “no recurring subscription fees for accessing your data.” Cycle & Ovulation Pro is the paid PowerPlug if you want it. Its titanium unibody uses ProRelease Technology, which “enables Ring PRO to be cut apart more easily in the event of swelling or injury to the finger.” The catches are real: it is the most expensive ring on this site, its phone requirements aren't stated on the US pages we checked, and its only published data is an in-house pilot on the older Ring AIR. See the Ultrahuman Ring PRO review and what Ultrahuman charges for.

3. Samsung Galaxy Ring: size 5, for Android phones

The Galaxy Ring also starts at size 5 and runs to 15, with a complimentary sizing kit, a titanium frame, 10ATM and IP68 ratings, a charging case in the box and no app subscription. Samsung highlights skin temperature readings while you sleep. Two things hold it back at small sizes in particular: Samsung rates sizes below 12 at up to 6 days a charge rather than 7, and GSMArena got about 5 days from a size 11. Beyond that, it doesn't work with iPhone, Energy Score insights and Find My Ring need a Samsung phone, and we found no peer-reviewed validation of it. The Galaxy Ring review and whether Galaxy Ring needs a subscription cover it.

4. Oura Ring 4: the smallest size, if you'll pay

The Oura Ring 4 is the only ring here sold in a size 4, and it runs to 15, so it covers the widest range of hands. It's also the Oura model tested directly against a Polar H10 in Dial et al. 2025, with a resting heart rate error of about 2% and an HRV error of about 6% over 536 nights (13 adults, nighttime readings only). Oura rates it at typically 5-8 days. If you want color, Oura also makes a Ring 4 Ceramic: zirconia ceramic over a titanium inner shell per Oura's support page, in four colors and sizes 4-15 per TechCrunch. The price of all that is the membership, $5.99 a month or $69.99 a year, without which you see three daily scores. Ring 4 is also off Oura's current ring list, though still listed on Amazon. Our Oura Ring 4 review and is the Oura Ring worth it weigh the fee.

5. RingConn Gen 2 Air: the lower-cost no-fee option

If cost matters more than cycle features, the Air gets you RingConn's no-fee app for less; RingConn lists it below Gen 2 and Gen 3 on its own store. It claims up to 10 days a charge with 90-minute fast charging, comes in sizes 6-14 with a free sizing kit, and works with iOS 17 and Android 10 or newer. It has no charging case, no sleep apnea monitoring and no published validation of its own. Our RingConn Gen 2 Air review covers what the lower price gives up.

6. Oura Ring 5: the lightest published weight, with a fee

Oura is the only brand here whose ring weight we could source: “from 2 grams (depending on ring size)” for the Ring 5. It lists Cycle Insights built on temperature trends, along with heart rate, HRV, blood oxygen, Symptom Radar and more, claims 6-9 days a charge, and works on iPhone and Android. But sizes start at 6, not 4 like Ring 4; Oura says Ring 5's “redesigned interior fits differently than Oura Ring 4”; most of its insights need the membership; and Ring 5 itself hasn't been through the published studies its predecessors have. See our Oura Ring 5 review.

Two situations have their own pages rather than a line in this one. For perimenopause and menopause, where the useful data is nightly temperature and broken sleep rather than any advertised feature, see best smart ring for menopause. And if you are buying one of these for somebody else, the sizing problem is the whole difficulty - it is solved on the smart ring gift guide.

What to check before you buy

1. Your size, with that brand's kit. Oura's kit is free on its store and sold on Amazon with a matching credit toward a Ring 5 (per Android Police). RingConn, Samsung and Ultrahuman send complimentary kits. Size again every time you switch brands, and even when you switch Oura generations. Our smart ring sizing guide has the steps.
2. Which finger. Oura recommends the index finger for best accuracy. If you plan to wear the ring alongside other jewelry, size the finger you'll actually use; see which finger to wear a smart ring on.
3. Whether you need cycle features, and what they cost. Gen 3 includes predictions with no fee. Oura's Cycle Insights come with the membership. Ultrahuman's is an optional paid PowerPlug.
4. Your phone. The Galaxy Ring is Android only. RingConn needs iOS 17 or Android 10 or newer.
5. How you'll return it. Rings bought on Amazon follow Amazon's return process. The Circular Ring 2 is brand-store only, on its own terms. Our warranty and returns guide compares them.

Mistakes to avoid

• Ordering by your jewelry size. Every brand here says its sizing differs from standard rings.
• Treating a cycle prediction as contraception. These are wellness estimates. The only FDA clearance in the picture belongs to Natural Cycles, a separate app.
• Expecting the headline battery at a small size. Samsung and Oura both tie battery to ring size.
• Paying monthly for something you could get free. If cycle predictions are the main reason you're buying, compare the Gen 3 (no fee) with Oura (membership) before you choose.
• Assuming Oura Ring 5 comes in your Ring 4 size. Ring 5 stops at 6 on the small end and fits differently.