Fi Mini GPS Tracker for Dogs

Fi’s smallest tracker: a 0.56 ounce GPS unit that slides onto any collar in a silicone case.

Who it suits

Small and toy dogs, or owners who want a very light tracker that goes on any collar.

Key facts

• Weighs 0.56 ounces and measures 1.18 x 1.65 inches (Fi)
• Rated for up to 2 months per USB-C charge (Fi)
• IP68 waterproof rating, tested in salt water (Fi)
• Comes with five silicone cases that attach it to any collar (Fi)
• Live GPS/LTE-M location, safe zone escape alerts and a lost mode on a paid GPS/LTE plan (Fi)

What reviewers say

Treeline Review: Jae Thomas tested it for Treeline Review (updated August 2026) and named it best for small dogs. It stayed in its strap during testing, though Thomas found the soft case attachment more secure for active dogs, and the battery lasted about six weeks. Safe zone exit alerts arrived noticeably later than on the Fi Series 3+, which Thomas put down to the Mini not coming with Fi’s home base. Treeline Review does not say whether the unit was a maker sample.

We did not test it ourselves.

Pros

• Very small and light
• Fits any collar
• Long battery life

Cons

• GPS/LTE plan required
• Slower escape alerts than the Series 3+, per Treeline Review
• Does not come with Fi’s home base, per Treeline Review

Good to know

• Use the more secure case style on active dogs so the tracker cannot slip off.
• Location depends on cell coverage; keep an ID tag on and your microchip details current.
• Check the collar fit on small dogs often; ask your vet about any rubbing.