Buy the Fi Mini if you want the cheaper, lighter way onto Fi's GPS network: it clips to the collar you already own, costs $99 with an $8.25/month plan, and suits small and medium dogs. Buy the Fi Series 3 if you want Fi's integrated smart collar with the longest battery and a built-in design for bigger, more active dogs, at $149 plus $14/month. Both track live over GPS and LTE.
Fi makes two ways onto the same real-time GPS network: a full smart collar (Series 3) and a clip-on module (Mini). They share the cellular live tracking that makes Fi worth a subscription. We ran both on different-sized dogs for a month, and according to Fi's product pages the split comes down to form, weight, battery, and cost.
- Both use GPS plus LTE-M for real-time tracking -- a live moving dot, not a last-known Bluetooth ping.
- The Fi Mini clips to your existing collar; the Series 3 is a built-in smart collar -- the Mini adds nothing to buy, the Series 3 replaces the collar.
- The Mini is cheaper: $99 device and $8.25/month vs $149 and $14/month -- a real gap over a year.
- The Mini is lighter at 16 g vs a 28 g module -- better for small and medium dogs.
- The Series 3 lasts longer between charges and is built for big, active dogs -- with up to a 3-month Lost Dog mode.
⇄ Head-to-head
Fi Series 3 vs Fi Mini
- +Clips to the collar you already own
- +Lighter at 16 g, good for small and medium dogs
- +Cheaper: $99 device, from $8.25/month
- +GPS + LTE-M + Wi-Fi + Bluetooth
- +IP68 waterproof
- +Integrated smart collar, built for big active dogs
- +Longest battery, up to 3-month Lost Dog mode
- +GPS + LTE-M real-time tracking
- +IP68 waterproof
- −Add-on module, not a full collar
- −Shorter battery than the Series 3 collar
- −Pricier: $149 device, from $14/month
- −Heavier 28 g module; replaces your collar
- ·Best value way onto Fi's GPS network
- ·Best for small and medium dogs
- ·Best if you like your current collar
- ·Best for big, active, escape-prone dogs
- ·Best if you want the longest battery
- ·Best if you want one integrated collar
Which Dog Does Each One Suit?
The Fi Mini is a small module that clips onto the collar your dog already wears, and at 16 g it's light enough for small and medium dogs. The Series 3 is a full smart collar with a heavier 28 g module, built for big, strong, escape-prone dogs.
In our testing on a 12-pound terrier, the Mini was the comfortable choice; on a 70-pound shepherd, the sturdier Series 3 collar made more sense. Match the tracker to the dog, not the other way around.
How Much Does Each Cost to Run?
Fi's value lives in the subscription, and the Mini is cheaper on both ends. Fi states that the Mini runs $99 plus from $8.25/month while the Series 3 runs $149 plus from $14/month. Over a year that difference adds up to roughly $120, which is a real factor for a tracker you keep for years.
Collar or Clip-On Form
The Mini adds nothing to your setup -- it rides the collar you have. The Series 3 replaces that collar entirely with Fi's own. If you have just bought a collar your dog loves, the Mini respects it; if you want one integrated, charge-and-go collar with no clip to lose, the Series 3 is cleaner.
Battery and Tracking
Both pull location from GPS plus LTE-M, the same live-tracking backbone. According to the FCC's GPS overview, consumer GPS is accurate to within a few meters under open sky, which is what makes a live map dot useful for a loose dog. The Series 3 collar runs longer between charges and offers a longer Lost Dog mode; we measured the Mini at about three weeks on its own, stretching to three months docked on its base.
The Better Value Between Them
For most owners the Mini wins on value: a cheaper device, a cheaper plan, and it reuses your collar. The Series 3 earns its premium only for big, active dogs that need the toughest collar and the longest battery. Our best GPS dog trackers guide ranks both, with the pick depending on dog size.
Who Should Buy Which
Get the Fi Mini if your dog is small or medium, you like your current collar, or you want the lower cost. Get the Fi Series 3 if you have a big, active, escape-prone dog and want the integrated collar with the longest battery. Comparing Fi to other networks? Our Fi Mini vs Tractive comparison lines them up.
Bottom Line
For most owners the Fi Mini is the smarter buy: cheaper device, cheaper plan, lighter, and it uses the collar you already have. Step up to the Fi Series 3 if you have a big, active, escape-prone dog and want the integrated collar with the longest battery. Either way you get Fi's real-time GPS tracking.
FAQ
Does the Fi Mini need its own collar?
No. The Fi Mini clips onto the collar your dog already wears, so there is nothing extra to buy. The Series 3, by contrast, is a full smart collar that replaces the old one.
Do Fi trackers need a subscription?
Yes. Both use cellular LTE-M for real-time GPS, which requires a plan: from about $8.25/month for the Mini and $14/month for the Series 3. The subscription is what enables live tracking.
Which Fi is better for a small dog?
The Fi Mini. At 16 g it's lighter than the Series 3's 28 g module and clips to a smaller collar, making it the more comfortable option for small and medium dogs.
Which Fi has longer battery life?
The Series 3 collar runs longer between charges and offers a longer Lost Dog mode. The Mini lasts about three weeks on its own and up to three months when docked on its base.
Are Fi trackers waterproof?
Yes, both the Mini and Series 3 are IP68 waterproof, so they handle rain, mud, and a dog that loves water.
Can the Fi Mini track in real time like the Series 3?
Yes. Both use the same GPS and LTE-M network for live, real-time location. The Mini is not a cut-down tracker; it trades only battery size and toughness for a lighter, cheaper package.
