One of the most common questions among fly anglers—whether they tie their own or buy them—is how many flies of each pattern they should carry. It’s a fair question, and while experience may shape your answer over time, there’s an old joke that sums it up pretty well:

The right number of flies to carry is three. One will inevitably find its way into a tree branch or the bottom of the river. Another will be tied onto your leader so you can actually fish. And the last one? Well, that’s for when another angler asks what the fish are biting on, so you can hold it up and say, “This fly right here—it’s my last one. But for twenty bucks, it’s yours.”

Jokes aside, for personal use on a day trip, I’ve always found that three or four of a particular pattern is a good number. That’s usually enough to get through the day without running out of a hot fly. If you’re heading out for a multi-day fishing trip, though, you’ll want to bump that number up—especially if you’re fishing remote waters where there’s no fly shop nearby.

As a Maine fishing guide, my perspective has shifted. When you’re tying flies onto the leaders of up to three anglers, those losses add up fast. More snags. More break-offs. More fish (hopefully) thrashing flies free. Because of that, I stock at least a dozen of my top-producing flies—the patterns that consistently put fish in the net. For flies that see occasional action, a half dozen usually does the trick. And for experimental patterns? Just a couple, because let’s be honest—some of those flies will end up catching more admiration than fish.

Even with careful planning, I undoubtedly find myself sitting down mid-season to replenish my stock of flies. It’s just part of the game. If you tie your own, it’s handy to bring along a travel fly-tying kit when heading out on a multi-day trip. A small vise, some basic tools, and a handful of common tying materials can be a lifesaver if you run low on a productive fly or need to match a hatch later in the hotel room.

At the end of the day, there’s no perfect number of flies to carry, but being prepared makes all the difference. And if you ever find yourself down to that last fly… just remember, it might be worth twenty bucks.