The short version: WHOOP 5.0 and WHOOP MG take the same strap as each other. WHOOP 4.0 takes a different one. Everything below is about making sure you know which group you are in.
Method 1 — the app (most reliable)
- Open the WHOOP app.
- Tap the device icon in the top right.
- Open Device Settings.
Your model is named there. This is the method to trust, because it reads the device itself rather than your memory of the box.
Method 2 — the back of the sensor
Take the sensor out of its band and turn it over. The model is printed on the casing. It is small, and on a well-worn device it can be faint, but it is there.
Method 3 — the clasp, by eye
This is the one worth learning, because it works across a table without an app.
- WHOOP MG — two small metal contacts sit in the clasp. They are the ECG electrodes; you rest fingers of the opposite hand on them to take a reading. If you can see them, you have an MG.
- WHOOP 5.0 — looks the same as MG from every other angle, but the clasp has no contacts.
- WHOOP 4.0 — noticeably larger overall, with a narrower clasp housing. Alongside a 5.0 the size difference is obvious; alone, it is less so.
Method 4 — when you bought it
WHOOP 5.0 and WHOOP MG were introduced in May 2025, replacing the 4.0. If your device predates mid-2025, it is almost certainly a WHOOP 4.0. This is a useful sanity check rather than proof — plenty of people have upgraded since.
Why MG and 5.0 share a strap
The two devices are built on the same hardware body. MG adds ECG and blood-pressure insights, and those additions live in the clasp electronics rather than in the dimensions of the housing. Since the housing is what a strap engages with, one strap fits both. Only the generation change — 4.0 to 5.0 — altered the housing enough to need a separate fit.
Still unsure? Choose the option that matches what the WHOOP app reports. If you order and then discover the app says something different, tell us before your strap ships and we will change it. Confirmed orders can also be returned within 14 days of delivery.
A note on WHOOP Body
WHOOP Body is apparel with a sensor pocket, worn on the torso or arm rather than the wrist. There is no strap involved, so nothing here applies to it. If you wear your sensor on your wrist, you are in the right place.