Oura Smart Ring 4 vs Oura - Ring 5 - Smart Ring - Size Before You Buy with OR5 Sizing Kit - Size 11 - Silver - (2026): which is safer?

Oura - Ring 5 - Smart Ring - Size Before You Buy with OR5 Sizing Kit - Size 11 - Silver - (2026) is the clear pick. Oura Smart Ring 4 carries a failing PFAS grade, and we never recommend buying a failing product.

Circular

Oura Smart Ring 4

PFAS grade

F 40/100

Overall grade

F 28/100

Verdict

Skip

Hazard flags

⚑ 3

Material

Titanium, stainless steel, polymers with water-resistant coating

Confidence

45%

PossibleWater-resistant coating polymer stability and composition

PossiblePolymer microparticle shedding from coating

PossibleSkin sensitization or irritation from coating additives

Why this grade

Our pick

Fitbit

Oura - Ring 5 - Smart Ring - Size Before You Buy with OR5 Sizing Kit - Size 11 - Silver - (2026)

PFAS grade

B 85/100

Overall grade

D 67/100

Verdict

Buy

Hazard flags

⚑ 3

Material

Titanium and stainless steel with glass sensor

Confidence

72%

PossibleElectronic component off-gassing or thermal breakdown

ReportedBiofilm and bacterial growth on sensor surfaces

PossibleGlass or metal micro-debris from wear

Why this gradeBuy

Both products run through the same public rubric: materials, coatings, brand disclosure, lab findings, and recalls, plus a beyond-PFAS hazard analysis. Grades are model-based estimates, not lab tests. How grades work →

More waterproof smart rings & bands: see the full ranking