If you’re picking between the Oura Ring Gen 3 and Gen 4, you’re not alone. The question “oura ring 3 vs 4 thickness — which is worth it?” comes up a lot. While they look similar at a glance, key differences in materials, sensors, sizing, fitness tracking accuracy and thickness make a difference. In this article we’ll walk through all the major upgrades, highlight where the Gen 3 still holds up, and help you decide if the newer model is worth the extra cost.
Design & Build: What Has Changed?
Material & finish
- The Gen 3 had a titanium exterior but paired it with an epoxy or internal layer for the sensor housing. (Android Central)
- The Gen 4 moves to an all-titanium body, removing the epoxy layer and giving a sleeker, more premium feel. (EntreResource.com)
Internal sensor layout & comfort
- Gen 3 features “three small raised ridges” inside the ring to house the sensors. (EntreResource.com)
- Gen 4 improves this with “just two slight bumps,” and the sensors are more recessed so they’re less noticeable and the ring sits flatter on the finger. (EntreResource.com)
Sizes & weight
- Gen 3 offers sizes roughly from 6-13 (depending on region/style). (Tom’s Guide)
- Gen 4 expands this to sizes 4-15 — more inclusivity for smaller and larger fingers. (Tom’s Guide)
- Width remains approximately the same at 7.9 mm. (Oura Help)
- Thickness: Gen 3 ~2.7-2.9 mm (depending on style) vs Gen 4 ~2.88 mm. (Android Central)
- Weight: Gen 3 around 4-6 g (depending on size) vs Gen 4 about 3.3-5.2 g for similar sizes. (Android Central)
Bottom line on build
If you’re very sensitive to comfort, the Gen 4’s flatter interior and lighter feel might matter. But if you already wear the Gen 3 and it’s comfortable, the change isn’t dramatic.
Thickness & “Oura Ring 3 vs 4 thickness”
One of the more specific comparison points is thickness:
- Gen 3: ~2.7 mm (Heritage style) to ~2.9 mm (Horizon style) in thickness. (Oura Help)
- Gen 4: ~2.88 mm thickness. (Tom’s Guide)
So despite the claims of “thinner,” in many styles Gen 4 is only marginally different — the difference will likely not be perceptible to most in day-to-day wear.
Sensors, Tracking & Features
Sensor upgrades
- Gen 3: Standard set of sensors (PPG for heart rate, SpO₂, temperature, accelerometer) and automatic activity detection. (Tom’s Guide)
- Gen 4: Introduces what Oura calls “Smart Sensing” — up to 18 sensing pathways (vs ~8 in Gen 3) allowing the ring to choose optimal pathways for measurements. (Android Central)
Tracking accuracy
- Reports suggest Gen 4 is more accurate in certain readings (for example, SpO₂ and heart rate in motion) thanks to improved algorithm + sensor layout. (Android Central)
- That said, many reviewers note that while Gen 4 improves, Gen 3 was already very good for sleep and readiness tracking. (Wareable)
Activity and health features
- Both rings support readiness, sleep tracking, temperature trends, and integrations with iOS/Android.
- Gen 4 adds more of those marginal improvements: better activity tagging, sometimes improved heart-rate metrics during activity. (Gadget Flow)
Battery Life & Charging
- Gen 3 claimed “up to 7 days” battery life; in reality many users report 4-5 days depending on usage. (Gadget Flow)
- Gen 4 claims “up to 8 days”; reviewers suggest more like 5-6 days with full usage, depending on what monitoring features are active. (Wareable)
- Charging base: Gen 4 comes with a more premium charging base (metal, square design) vs Gen 3’s plastic base. (Tom’s Guide)
Price & Value
- Gen 3 originally launched at a lower price; now that Gen 4 is out, Gen 3 often has better discounts. (Wareable)
- Gen 4 starts at around US$349 as launch price (varies by finish) — about US$50 more than the entry Gen 3 models. (Tech Advisor)
- If budget is important, Gen 3 represents better value for many users because you still get the core experience.
Should You Upgrade or Buy Which?
Buy Gen 4 if you:
- Want the latest build and materials, best possible sensor layout and future-proofing.
- Have fingers at very small or large sizes (4-15 sizing range).
- Care about marginal comfort/fit improvements (smoother interior, lighter feel).
Stick with or buy Gen 3 if you:
- Your Gen 3 already works well and you’re satisfied with comfort/fit.
- You want to save money and are okay with slightly older hardware.
- You’re fine with the slightly more raised sensor layout and slightly fewer sizing options.
Oura Ring Gen 3 vs Gen 4: What’s the Difference?
Here’s a detailed breakdown of how the Oura Ring Gen 3 and Gen 4 compare — what’s new, what’s stayed the same, and how the thickness/fit differs.
Key Similarities
- Both rings offer core health-tracking features: heart-rate monitoring, heart-rate variability (HRV), respiration, temperature trends, sleep staging and readiness scoring. (Tom’s Guide)
- Both are water resistant to about 100 m / 328 ft, meaning they’re suitable for swimming and general wear. (Oura Help)
- The outer width of the ring remains the same for both models: approx 7.9 mm. (Android Central)
Should You Upgrade from Gen 3 to Gen 4?
- If you value marginal improvements — smoother interior, slightly improved sensors, expanded size range, full titanium build — then upgrading makes sense.
- If you’re already using Gen 3 and it fits comfortably, you may not need to upgrade just yet, as many core features remain very similar. (Android Central)
- If you’re buying new and choosing between them, Gen 4 is the newer version with more future-proofing.
Summary Table
| Feature | Gen 3 | Gen 4 |
| Materials & interior | Titanium exterior + epoxy interior; internal sensor bumps | Full titanium body; sensors recessed |
| Width | ~7.9 mm | ~7.9 mm |
| Thickness | ~2.7-2.9 mm | ~2.88 mm approx |
| Weight | ~4-6 g | ~3.3-5.2 g |
| Size range | ~6-13 | ~4-15 |
| Sensor signal paths | ~8 | ~18 |
| Battery life claim | Up to ~7 days | Up to ~8 days |
| Launch price | Lower than Gen 4 | Higher starting price |
Reflexiones finales
In short: The Oura Ring Gen 4 brings refinements rather than radical changes compared with Gen 3. The thickness is very similar, so you’re not trading off “bulkier” for “slimmer”. But the interior feel, materials, size options and sensing accuracy are improved.
If you’re using Gen 3 and it meets your needs, you’re still in good shape. If you’re shopping now for the best version, Gen 4 is the one to go for.