Pick Fi Series 3+ if
- You want weeks between charges
- Your dog is big, strong or rough on gear
- You want the tracker built into the collar
Pick Tractive DOG 6 if
- You want the lowest cost, now and later
- You want resting heart and breathing rates
- You travel abroad, or also track a cat
Our overall pick is the Fi Series 3+. A tracker only helps if it's charged when your dog gets out, and the Fi lasts weeks longer between charges. The Tractive DOG 6 is the better buy if cost matters most.
Fi vs Tractive at a glance
| Fi Series 3+ | Tractive DOG 6 | |
|---|---|---|
| Device price | $129 | $79 ($89 for the XL) |
| Plans | $99 / 6 mo · $189 / yr · $339 / 2 yr | $144 / yr · $204 / 2 yr · $360 / 5 yr |
| Year one | $318 | $223 |
| Two years | $468 | $283 |
| Battery (claimed) | 2 weeks to 3 months, with the Fi Base at home | 6–14 days (DOG 6); up to 6 weeks (DOG 6 XL) |
| When your dog is lost | Lost Dog Mode: updates every few seconds, about 2 days of battery | LIVE mode: updates every 2–3 seconds, turns off after 5 minutes unless extended |
| Escape alerts | Safe Zones | Virtual Fences: safe zones and no-go zones |
| How it attaches | Built into the collar band | Clips onto your dog's collar |
| Dog size | XS (under 10 lb) to XL (95 lb and up) | Over 9 lb; XL for over 44 lb |
| Network | AT&T LTE-M | Partner networks, LTE-M with 2G fallback |
| Where it works | US, Canada, Mexico | 175+ countries |
| Health and behavior | Activity, sleep, barking, licking, scratching, eating, drinking | Activity, sleep, resting heart and breathing rate, barking, scratching |
| Waterproof | IP68 and IP66K | IP68 |
| Returns / warranty | 30 days / 1 year | 30 days / 2 years |
| For cats | No (Fi Mini instead) | No (CAT 6 Mini instead) |
Prices as listed by Fi and Tractive, October 4, 2026. Battery figures are the brands' claims.
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Battery: Fi's biggest advantage
Fi says the Series 3+ lasts up to 2 weeks on a very active dog and up to 3 months on a calm one, because it rests on its base station, your phone or your Wi-Fi while your dog is home. Tractive's DOG 6 lasts up to 14 days with a Power Saving Zone and about 6 without. In daily life that's the difference between charging once a month and charging every week.
There's one exception. If your dog is over 44 pounds, Tractive's DOG 6 XL carries a much bigger battery, rated up to 6 weeks with a Power Saving Zone. That closes most of the gap for big dogs, for $89.
Finding a lost dog
Both switch to fast live updates when you need them. Fi's Lost Dog Mode updates every few seconds and runs about 2 days on a charge, long enough for most searches. It also has an LED you can switch on, and Search Party can alert other Fi users nearby. Tractive's LIVE mode updates every 2–3 seconds but shuts off after 5 minutes unless you extend it, which saves battery. Tractive adds a light, a sound and a Bluetooth radar that points you toward your dog when you're close, even without a cell signal.
Escape alerts
Both alert you when your dog leaves an area you set. Tractive says its alerts usually arrive within a couple of minutes, and almost instantly in LIVE mode. Fi doesn't publish a figure; Dogster measured 2 to 12 minutes of lag on Fi's Safe Zone alerts. Owners of both report the occasional false or late alert. We're timing the Fi on our own dogs now, with Tractive next, and will post the results in each review.
Cost over time
Tractive is cheaper at every point. Year one is $223 vs $318. Over two years it's $283 vs $468. Over five years, at today's prices, Tractive's five-year plan brings the total to about $439, while Fi comes to about $996 using two-year plans plus one year. Fi also has no plan longer than two years. See what trackers really cost for every brand.
Fit and build
The Fi tracker sits inside its own collar band, so there's nothing to snap off. That suits big, strong dogs and dogs who run through brush. The Tractive clips onto the collar you already use; a common complaint about it is the clip coming loose. The two trackers weigh about the same (Tractive 1.4 oz, about 40 g; Fi 47 g), and the Tractive works with any collar or harness you like.
Health and behavior tracking
Both track activity and sleep. Tractive goes further on vital signs: after a week it reports resting heart rate and breathing rate, and it can alert you to changes over time. Fi focuses on behavior, flagging barking, licking, scratching, eating and drinking. Neither one diagnoses anything.
Coverage and travel
Fi runs on AT&T's LTE-M network in the US, Canada and Mexico. Tractive's SIM uses partner networks, LTE-M first with a 2G fallback, and works in 175+ countries. If you're in a rural area, check both coverage maps for the places your dog goes. Tractive says it stores positions while out of coverage and uploads them later; Fi doesn't document that. More in trackers without cell service.
Our verdict, by dog
- Big, active dog that roams: Fi Series 3+, or the Tractive DOG 6 XL if budget is tight.
- Small or medium dog: Tractive DOG 6 for value; Fi if you want the longer battery.
- You'll forget to charge it: Fi.
- You want health trends: Tractive.
- A dog and a cat: Either brand covers both in one app. For the cat, we'd pick Tractive's CAT 6 Mini over the Fi Mini.