If there's one question I get asked more than almost any other, it's this: "Which long line length should I get?"
And my honest answer always surprises people, because it isn't a number. It's a question right back at them: what are you actually going to use it for?
Because here's the thing I've learned from using long lines with Mack nearly every single day — the right length has very little to do with how big your dog is, and almost everything to do with the job you need it to do. A 15m line isn't "better" than a 5m line. They're different tools for different moments, the same way you wouldn't use a hammer for every job in the shed.
So let me walk you through what each length is genuinely good for, based on actually using all three, and then I'll tell you how I ended up solving the whole question for myself.
First — why length matters more than people think
A long line is all about one trade-off: freedom versus control.
The longer the line, the more room your dog has to move, sniff and explore — which is exactly what makes long lines so brilliant for recall training and decompression walks. But more length also means less immediate control, more line to manage, and more that can go wrong if your dog bolts toward something before you've built up reliable recall.
Get the balance right for the situation you're in, and a long line transforms your walks. Get it wrong — too long for a tight space, or too short for the freedom you were hoping to give — and it just becomes a tangled, frustrating mess. That's why I don't think of it as "what length should I buy" so much as "what length do I need right now."
The 5m — your everyday control line
The 5m is the one people underestimate, and it's the one I reach for most in built-up areas.
Think of it as the bridge between a normal lead and full long-line freedom. It gives your dog noticeably more room to move and sniff than a standard 1.2m lead, but it's still short enough to gather up quickly when you need to. That makes it ideal for:
- Early recall work, when your dog is still learning and you want them close-ish
- Busy or tight spaces — footpaths, car parks, anywhere with people or traffic nearby
- High-distraction environments where you need to be able to reel your dog in fast
If your dog is right at the start of their recall journey, or you mostly walk in places where 15m of trailing line would be a hazard, the 5m is honestly where I'd tell you to begin. It's the most controllable of the three, and control is everything when you're building trust.
The 10m — the all-rounder
If the 5m is the cautious starter and the 15m is the freedom machine, the 10m sits right in the sweet spot — and it's the length most people end up using most often.
Ten metres gives your dog real freedom to range ahead, circle back, and make their own choices, which is exactly what you want when you're proofing recall in open spaces. But it's still manageable. You can keep enough of it gathered to stay in control, and let it out as your dog earns more trust. For most parks, ovals and open trails, the 10m does the job beautifully.
If you're past the very early stages and your dog has some reliability but isn't bombproof yet, the 10m is the one that'll probably live on your belt clip. It's the workhorse.
The 15m — maximum freedom
The 15m is the one that makes people's eyes light up, and I get it — fifteen metres of line means your dog can genuinely stretch out, run, and explore while you stay connected.
This is the line for big open spaces: quiet beaches, large empty ovals, wide-open paddocks. It's perfect for letting a dog who's almost ready for off-lead enjoy something close to it, safely. When Mack gets to properly open up on the 15m at the beach, you can see the difference in him — it's freedom with a safety net.
But I'll be straight with you, because that's the whole point of these posts: the 15m only makes sense when you've got solid recall and the space to use it. In a small or busy area, fifteen metres of line is a tripping hazard and a tangle waiting to happen. And one honest note on sizing — the 15m has a bit more weight to it, so for smaller dogs it can be a touch heavy. For a big, strong dog it's no issue at all, but it's worth knowing.
So which one should you actually buy?
Here's where I'll be completely honest with you, because it's exactly how it played out for me.
I started out thinking I'd pick the length. One line to do everything. And it took me about a fortnight of real-world walks to realise that was never going to work — because the length I needed kept changing depending on where we were and what we were doing. Tight footpath to the park? I wanted the 5m. Open field once we got there? The 10m. Beach day on the weekend? The 15m, every time.
I wasn't choosing between them. I was using all three, for different jobs, and I'd have saved myself money buying them together from the start.
That's genuinely why we put together the Long Line Bundle — all three lengths, 5m, 10m and 15m, in one go, for less than buying them one at a time. It's not a gimmick; it's just the honest answer to "which length do I need," which turned out to be "all of them, for different moments." If you'd rather start with a single length while you find your feet, you can absolutely grab one on its own — but if you already know recall training is going to be a big part of your dog's life, the bundle's the smarter buy.
A few honest cautions
Whichever length you go for, a long line is a tool, not a magic fix — and it needs to be used safely. Always supervise your dog closely, never wrap the line around your hand, and build up your dog's freedom gradually as their recall improves rather than handing them 15m on day one.
I've made my share of long-line mistakes over the years, so if you want to skip a few of mine, have a read of 5 Common Mistakes People Make with Long Lines before your next walk.
Want more honest, tried-and-tested advice for big dog owners? Have a browse of our Leads and Collars collection — every long line we stock has been put through the Mack test, in every length, in all weathers.
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