Oura Ring 4

Oura Ring 4 is a ring from 2024, sitting in the premium band at an indicative $349.

It reads 18 of the 33 signals this comparison tracks. Nothing at all from body composition. Rarer readings it does take: cardiovascular age and sleep efficiency.

By sensor class: 7 at high accuracy and 6 at consumer grade. That grade is my classification of the hardware, not a lab test. Those readings come from an optical heart rate sensor, an optical blood oxygen sensor, a skin temperature sensor and an accelerometer. Blood oxygen is measured through the night, not continuously through the day.

Its 5-8 days per charge are the longest of the 7 devices of its kind here that publish a figure. Rated 100m / WR100, fine for swimming. It weighs 4 g. Ring sizes US 4-15. An Oura Membership subscription is required to use it.

Flagship ring; 18-path PPG, overnight SpO2, no ECG/GPS/BP; full metrics need membership.