Fi makes GPS dog collars, and this guide covers two Fi collars. Fi describes the Fi Series 3+ as a GPS dog collar with “live location tracking, escape alerts, and sleep and step monitoring,” and calls the Fi Ultra “the ultimate off-leash GPS tracking solution, powered by T-Satellite with Starlink.” This guide sets out what Fi publishes about each one.
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We do not test products. Everything below comes from Fi’s own pages on fitracking.com, checked on 12 October 2026: the Series 3+ page, the Ultra page, the membership page and Fi’s published comparison tables.
The Two Fi Collars at a Glance
| Spec, as Fi lists it | Fi Series 3+ Smart Collar | Fi Ultra Smart Collar |
|---|---|---|
| Location | Live GPS over a cellular connection | Live GPS over cellular and T-Satellite powered by Starlink |
| Battery life | Battery up to 3 months | Battery up to 5 days |
| Charging | Wireless charging base | USB-C |
| Device weight | Device weight 47 g (1.66 oz) | Device weight 69 g (2.43 oz) |
| Water, in Fi’s words | Waterproof, dirtproof | Waterproof, leak-proof, mud-proof and ultra durable |
| Containment | Unlimited geofences with 24/7 escape alerts | Geofences and escape alerts, plus Fi CallBack™ |
| Coverage | North America and much of Europe, 35 countries and territories | United States only |
| Subscription | Required | Required |
| First-year cost, as Fi structures it | One-year membership, device included; check current price | Hardware kit plus a one-year membership; check current price |
Fi lists a subscription as required for both collars. Prices change, so check current price on Fi’s site before buying.
How We Researched This Guide
We read Fi’s product page for each collar, Fi’s membership page, and the specification tables Fi publishes on its comparison pages. For each collar we read how it finds the dog, what it alerts you to, what it tracks, how long Fi says the battery runs, how it charges, where it works, and how Fi structures the first-year cost. Every figure in this guide comes from Fi.
1. Fi Series 3+ Smart Collar
Suits: in our reading of the specs, anyone who wants live location, escape alerts, and sleep and step monitoring on one collar.
Fi describes the Series 3+ as a GPS dog collar with “live location tracking, escape alerts, and sleep and step monitoring.” Fi’s comparison table lists its location method as live GPS over a cellular connection, with unlimited geofences and 24/7 escape alerts. For health and behaviour, the same table lists activity, sleep, barking, scratching, licking, eating and drinking detection, plus AI vet records.
On battery, Fi’s page promises “up to 3 months of battery” and says you “power up with wireless charging.” For walks after dark, Fi says you can “keep an eye on your dog at night with colorful LED lights.”
What the spec sheet says:
- Location: live GPS over a cellular connection
- Containment: unlimited geofences with 24/7 escape alerts
- Battery: up to 3 months, charged on a wireless charging base
- Device weight: 47 g (1.66 oz)
- Water: Fi’s page calls it “waterproof, dirtproof”
- Frame: industrial-strength stainless steel; Fi lists 500+ lbs resistance
- Light: multicolor LED light
- Sizes: a modular design that Fi says fits XS to XL dogs
- Collar: ships with a Fi collar
- Phones: iOS and Android
- Coverage: North America and much of Europe, 35 countries and territories
- Trial: 30-day risk-free trial
The membership: Fi’s membership page says “every membership includes your dog’s personal app, the Series 3+ Collar and constant access to invaluable data.” Fi lists the option to keep tabs on multiple dogs all within a single account, and support by phone, chat and email.
Drawbacks on paper:
- A subscription is listed as required in Fi’s comparison table.
- It runs on a battery that needs charging; Fi lists up to 3 months per charge on the wireless charging base.
- Coverage, as Fi lists it, is North America and much of Europe, 35 countries and territories.
Pricing: Fi’s comparison table lists the first-year cost as a “one-year membership, device included.” Check current price on Fi’s site.
Who it suits: In our reading of the specs, anyone in Fi’s listed coverage area who wants escape alerts and health tracking on one collar, with a membership.
See the Series 3+ on Fi’s site
2. Fi Ultra Smart Collar
Suits: in our reading of the specs, dogs who roam beyond cell coverage, in the United States, where Fi lists the Ultra’s coverage.
Fi describes the Ultra as “a rugged GPS dog collar for dogs who roam beyond cell coverage.” Fi’s comparison table lists its location method as live GPS over cellular and T-Satellite powered by Starlink, and Fi’s comparison page says it adds T-Satellite powered by Starlink, “so it keeps reporting where there is no cellular signal at all.”
The Ultra also has a recall feature, Fi CallBack™. Fi’s page puts it as “one tap calls them back,” and says you “manually tap right in the app when you’re ready for your dog to return.” The signal is sound and vibration, which Fi calls “strictly humane recall signaling.”
What the spec sheet says:
- Location: live GPS over cellular and T-Satellite powered by Starlink
- Containment: geofences and escape alerts, plus Fi CallBack™
- Recall: sound and vibration through Fi CallBack™
- Battery: up to 5 days on a single USB-C charge
- Device weight: 69 g (2.43 oz)
- Water: Fi’s page says “waterproof, leak-proof, mud-proof and ultra durable”
- Fit: attaches to any collar, harness or working-dog vest, within the thickness limit in Fi’s comparison table
- Health: smart vet records, walks and car rides
- Phones: iOS and Android
- Coverage: United States only
- Trial: 30-day risk-free trial
Drawbacks on paper:
- A subscription is listed as required in Fi’s comparison table.
- Fi lists the battery at up to 5 days on a single USB-C charge.
- Fi lists coverage as United States only.
- Fi’s comparison page says activity and behaviour tracking “come from pairing it with a Series 3+ or Mini.”
Pricing: Fi’s comparison table lists the first-year cost as a hardware kit plus a one-year membership. Check current price on Fi’s site.
Who it suits: In our reading of the specs, anyone in the United States whose dog roams beyond cell coverage and who wants a recall signal in the app.
Series 3+ or Ultra: How to Choose
Start with where you walk
On the spec sheet, the Series 3+ works in North America and much of Europe, and the Ultra in the United States only. Fi lists satellite tracking for the Ultra, through T-Satellite powered by Starlink.
Then look at charging
On the spec sheet, the Series 3+ battery runs up to 3 months on its wireless charging base, and the Ultra battery up to 5 days on a USB-C charge.
Check how the cost is structured
Fi lists a subscription as required for both collars. Fi’s comparison table lists the Series 3+ first-year cost as a one-year membership with the device included, and the Ultra as a hardware kit plus a one-year membership. Check current price for both on Fi’s site.
Plan for the walk
A tracker is one part of your kit. For what else to carry on the trail, see our dog trail safety essentials, and for trackers from other brands, see our roundup of GPS trackers for dogs.
FAQ: The Fi Collar
Does the Fi collar need a subscription?
Yes. Fi’s comparison table lists a subscription as required for both the Series 3+ and the Ultra. Fi’s membership page says every membership includes the Series 3+ Collar. Check current pricing on Fi’s site.
How long does the Fi collar battery last?
Fi lists battery life of up to 3 months for the Series 3+, charged on a wireless charging base, and up to 5 days for the Ultra, charged over USB-C.
Is the Fi collar waterproof?
Fi calls the Series 3+ waterproof and dirtproof, and describes the Ultra as waterproof, leak-proof, mud-proof and ultra durable.
Does the Fi collar work outside the United States?
Fi lists Series 3+ coverage as North America and much of Europe, 35 countries and territories. Fi lists the Ultra as United States only.
Does the Fi collar send escape alerts?
Yes. Fi lists unlimited geofences with 24/7 escape alerts for the Series 3+, and geofences and escape alerts plus Fi CallBack for the Ultra.
Summing Up
On the spec sheets, the Fi Series 3+ Smart Collar lists live GPS over a cellular connection, escape alerts, activity and sleep detection, and battery life of up to 3 months. The Fi Ultra Smart Collar lists live GPS over cellular and T-Satellite powered by Starlink, Fi CallBack™ recall, battery life of up to 5 days and coverage in the United States only. Fi’s comparison page says the Ultra’s activity and behaviour tracking come from pairing it with a Series 3+ or Mini. Fi lists a subscription as required for both. For more trip planning, see our adventure dog travel guide.
Sources
Sources, checked 12 October 2026: Fi, Fi Series 3+ Smart Collar, Fi Ultra Smart Collar, Membership, and the comparison pages Fi vs. Tractive DOG 6 XL and Fi vs. Apple AirTag. Prices change; check the vendor before buying.