A collar tracker should weigh under 2% of the cat's body weight including the collar and the tag — that is 80 g on a 4 kg cat, and a 45 g device plus a 15 g collar plus a 4 g tag lands at 64 g, or 1.6%. Battery life tracks the update interval almost linearly: 2 to 4 days at 1-minute updates, 5 to 7 days at 5 minutes, 3 to 4 weeks at 60 minutes. Weigh the whole kit on a 1 g scale and read the runtime at your chosen interval before anything else.
A tracker finds a cat that is already out. It does not keep one in, and it is not identification; the 15-digit microchip remains the legal link back to you.
Weight: the 2% working number
The commonly quoted 5% figure is unhelpful for cats: 5% of 4 kg is 225 g, which no wearable should approach. Two percent is the working ceiling — 80 g at 4 kg, 60 g at 3 kg, 100 g at 5 kg. A GPS unit runs 25 to 45 g, a breakaway collar 10 to 20 g, an ID tag 2 to 5 g, so a 4 kg cat has 30 to 40 g of headroom after a mid-weight device. Kittens under 6 months or under 1.5 kg should not carry one at all. Weigh on a kitchen scale at 1 g resolution, and reweigh every 30 days, because a cat that loses 300 g in a month has just lost 6% of its body weight and the collar margin with it.
Reading the battery number honestly
Published runtimes assume a warm room and a good signal. The same unit gives 2 to 4 days at a 1-minute interval, 5 to 7 days at 5 minutes, 8 to 12 days at 15 minutes, 2 to 3 weeks at 30 minutes and 3 to 4 weeks at 60 minutes. Motion-triggered reporting, where the device stays quiet until the cat moves, saves 40% to 70% and is the single most useful setting for an indoor cat that goes out twice a day. A 500 to 1200 mAh cell charges in 1 to 2 hours and lasts 300 to 500 cycles, so 2 to 3 years is the realistic life of the device rather than the 5 years the box implies. Cold is the other variable: at 0°C expect 20% to 30% less runtime, and charging below 0°C or above 45°C damages the cell permanently.
What a 5-minute interval actually costs you
Location lag is the part buyers miss. A cat walks at roughly 0.5 to 1 m per second when it is exploring, so a 5-minute gap can put the pin 150 to 300 m from where the cat is now, and a 60-minute gap can put it 2 to 3 km away. For a cat that slips out at night, set the app to 1-minute updates for the first 2 to 3 hours of a search, then drop back to 10 minutes once you are within 100 m. GPS accuracy itself is 5 to 15 m under open sky, 20 to 50 m between buildings, and usually no fix indoors, where it falls back to Wi-Fi positioning at 20 to 50 m or to the last known point.
| Type | Weight (g) | Runtime at 5 min | Typical accuracy | Works indoors |
|---|---|---|---|---|
| Bluetooth tag only | 8–12 | 180–365 days | 10–30 m by relay | yes, same room |
| GPS with cellular | 30–45 | 4–7 days | 5–15 m outdoor | no |
| GPS plus Wi-Fi | 25–35 | 5–10 days | 20–50 m indoor | partial |
| Radio with base station | 20–30 | 7–14 days | 30–100 m | yes, one building |
| GPS with activity log | 35–50 | 3–5 days | 5–15 m outdoor | no |
Fitting: breakaway, 2 fingers, 1 to 2 cm of margin
The buckle must be a breakaway type that releases under 2 to 3 kg of pull, because a collar that holds is a strangulation risk. Two fingers should slide under the band, and 1 to 2 cm of adjustment should be left so the fit survives a winter coat. Check weekly: a collar that was right in October is tight by December. Avoid elastic bands entirely — a cat can push a front leg through one and panic. Webbing 6 to 8 mm wide spreads the load on a 3 to 4 kg cat; a 10 to 12 mm buckle suits cats over 5 kg. If the cat fights handling for 3 minutes, use the same 2-person towel wrap described in how to use a cat inhaler and fit the collar in 2 short sessions.
The 4 wearing risks worth watching
One, fur and skin: a 1 to 2 cm band of thinning or a red crease appears in 3 to 4 weeks if the fit is wrong, and long-haired cats mat under a heavy device. Two, behaviour: scratching at the neck more than 5 times an hour, head shaking, or rubbing along furniture for 10 minutes after fitting means the load is too high. Three, movement: a cat that stops jumping to a 1.2 m shelf it used daily is protecting its neck; remove the device for 2 weeks and reassess. Four, the collar itself: any sign of fraying at the D-ring, or a buckle that needs force to open, retires the collar immediately. Remove the tracker for 10 to 14 days after any surgery, and skip it for cats with neck or spine problems.
When a tracker is the wrong tool
Indoor cats that never leave a flat get more from a Bluetooth tag at 8 to 12 g than from a 45 g GPS unit, and a cat in one building is better served by a radio system with a 30 to 100 m range and no data plan. A tracker does not replace identification: keep the microchip registration current, since a shelter scans 15 digits before it calls anyone, and the record-keeping habit is the same one in the vaccine record tracker. Running costs come from the data plan and the replacement cycle, not the device, and the yearly arithmetic is in our cost tool.
Search order when the pin goes live
Most lost indoor cats are found within 200 to 300 m of home, and most of those within 48 hours, so work outward in rings: the 5 nearest gardens, then 100 m, then 300 m. Start at 1-minute updates, walk the ring with the phone at chest height, and stop every 20 m to let the reading settle for 15 seconds. If the tracker shows a fix that has not moved for 30 minutes, the device may be off the cat — check the last 3 positions for a straight line, which usually means a slipped collar.
Setup in 20 minutes
- Weigh device, collar and tag on a 1 g scale; keep the total under 2% of body weight.
- Set 5-minute reporting for daily use and save a 1-minute profile for searches.
- Fit with 2 fingers of slack, test the breakaway by hand, and recheck at 7 days.
- Charge on a fixed day every 3 days, and treat 20% battery as the trigger.
- Write the microchip number and the tracker ID in one place, so a finder has 2 ways to reach you.
Terms mentioned in this article
Frequently asked
How much weight can a cat carry on a collar?
Keep the whole kit under 2% of body weight: 80 g on a 4 kg cat, 60 g on a 3 kg cat. A GPS unit is 25 to 45 g, a breakaway collar 10 to 20 g and a tag 2 to 5 g, so a mid-weight device leaves 30 to 40 g of headroom. Kittens under 6 months or under 1.5 kg should not wear one, and the total should be reweighed every 30 days.
How long does a cat GPS tracker battery last?
Runtime follows the update interval: 2 to 4 days at 1-minute reporting, 5 to 7 days at 5 minutes, 8 to 12 days at 15 minutes, and 3 to 4 weeks at 60 minutes. Motion-triggered reporting saves 40% to 70%. Expect 20% to 30% less runtime at 0 degrees Celsius, and plan on 300 to 500 charge cycles, which is 2 to 3 years.
Can a tracker replace a microchip?
No. A shelter scans the 15-digit ISO microchip before it phones anyone, so registration has to stay current regardless of what is on the collar. A tracker helps only while it has battery and signal, and it can come off with the collar. Use both, and keep the chip number and tracker ID written in one place so a finder has 2 ways to reach you.