Apple Watch Series 9

The index converts the published five-point rating using a fixed scale. It preserves order and ties; it is neither a new performance measurement nor a quality percentage.

For example: 3.0/5 → 36; 4.0/5 → 64; 4.5/5 → 81; 5.0/5 → 100.

Index = 100 × (rating out of 5 ÷ 5)², rounded to the nearest integer.

Equal original ratings keep an equal index. Adding models does not change the scale.

Comparison guidelines

0 points: equal index. 1–7: small gap. 8–14: visible advantage. 15 or more: large gap. These are editorial guidelines, not statistical significance thresholds.

Indices derived from external reviews retain their original rating and source. Methods and dates may differ, so these comparisons do not declare an automatic winner.