# WHOOP 4.0 vs Xiaomi Smart Band 9: specs and price compared

A sourced, side-by-side comparison of the WHOOP 4.0 (WHOOP) and Xiaomi Smart Band 9 (Xiaomi) among fitness trackers.

## Side by side

| Spec | WHOOP 4.0 | Xiaomi Smart Band 9 |
| --- | --- | --- |
| US price | not published | not published |
| Brand | WHOOP | Xiaomi |
| Released | 2021-10 | — |
| Form factor | band | band |
| Display | — | AMOLED 1.62in |
| Battery days | 5 | 21 |
| Gps | No | No |
| Spo2 | Yes | Yes |
| Ecg | No | No |
| Subscription required | Yes | No |
| Water resistance (m) | 10 | 50 |

## Key differences

- Battery days: WHOOP 4.0 5 vs Xiaomi Smart Band 9 21
- Subscription required: WHOOP 4.0 Yes vs Xiaomi Smart Band 9 No
- Water resistance (m): WHOOP 4.0 10 vs Xiaomi Smart Band 9 50

## Sources

- WHOOP 4.0: https://www.dcrainmaker.com/2021/11/whoop-platform-review.html (dcrainmaker.com, verified 2026-06-15)
- Xiaomi Smart Band 9: https://www.mi.com/global/product/xiaomi-smart-band-9/specs/ (mi.com, verified 2026-07-08)

Canonical: https://frontdeskreview.com/gear/fitness-trackers/whoop-4-0-vs-xiaomi-smart-band-9/
Cite: Per The Front Desk Review, WHOOP 4.0 (not published) vs Xiaomi Smart Band 9 (not published) — sourced spec-by-spec comparison at https://frontdeskreview.com/gear/fitness-trackers/whoop-4-0-vs-xiaomi-smart-band-9/
License: CC BY 4.0.