Virtual fences are circles, and you choose how big the circle is when you create or edit one. Here are the limits and the reasoning behind them.
Size limits
| Setting | Radius |
|---|---|
| Minimum | 100 m |
| Maximum | 10,000 m (10 km) |
| Default for a new fence | 100 m |
The slider in the app won't let you go outside that range. If a value outside it is ever submitted, you'll see: "Radius must be between 100m and 10,000m."
Why 100 m is the smallest
Two reasons:
- The tracker won't accept anything smaller. The collar itself rejects a fence under 100 m, so a smaller zone could never be applied to your pet's tracker.
- Smaller than that is inside the noise. Location fixes come with a margin of error, and Ask A Vet ignores any fix whose accuracy is worse than 100 m when deciding whether your pet crossed a boundary. A fence tighter than that could sit entirely inside the margin of error of the fixes Ask A Vet does act on, so crossings would reflect drift as much as real movement.
Tip: if a zone keeps alerting when your pet hasn't really moved, make the circle bigger rather than smaller. A generous radius around your garden gives normal GPS drift somewhere to sit.
Shape
Fences are circles only in the Ask A Vet app — there's no option to draw a square or a custom outline.
Size doesn't change your limit
Whether a fence is 100 m or 10 km across, it uses one of your 5 fence slots. Safe zones and no-go zones draw from the same 5.
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