Selecting the right hook size is a crucial step in fly tying and fly fishing success. The size and shape of a hook will determine how well your fly imitates natural prey, how well it floats or swims and, ultimately how effectively you hook and land fish.
This fly hook size guide will help you navigate the numbering system, choose the best hooks for different fly patterns, and avoid common mistakes so you can tie better flies and catch more fish.
Understanding Hook Sizes
Before actually selecting a hook, you'll need to understand how hook size works. The sizing numbering system can be confusing at first, but once you grasp the basics, you’ll be able to match hook sizes to different fly patterns confidently.
Fly Hook Sizing
- Hook size follow a reverse numbering system—the larger the number, the smaller the hook (e.g., a size 20 hook is much smaller than a size 2).
- Hooks larger than size 1 are labeled with an “aught” (/) system, such as 1/0, 2/0, or 3/0, where bigger numbers indicate bigger hooks.
- Hook thickness varies, with standard, heavy-wire, and light-wire hooks designed for different fly types.
- Heavy-wire hooks are ideal for strong fish and sinking patterns, while light-wire hooks keep dry flies buoyant.
Choosing the right hook size ensures that your fly maintains proper proportions and an effective presentation in the water.
Fly Hook Size Guide – Choosing the Right Hook for Each Fly Type
Selecting the proper hook size is essential for tying flies that closely match natural insects and baitfish. Using the right size helps improve your presentation, ensures effective hook sets, and ultimately increases your success on the water. Here’s a breakdown of the ideal hook sizes and wire gauges for different fly types and fishing situations.
Dry Fly Hook Sizes
- Small mayfly and midges: Size 18–24
Medium mayfly, caddisfly, and terrestrials: Size 12–16 - Large mayfly and attractor patterns: Size 8–10
- Lighter wire hooks help maintain buoyancy.
- Popular dry fly hooks: Look for Tiemco, Daiichi, and Mustad dry fly hooks, which are designed with fine wire and standard-length shanks.
Nymph and Wet Fly Hook Sizes
Nymphs and wet flies imitate underwater insects, making hook weight and shape crucial for proper drift and sink rates.
- Small nymphs and emergers: Size 16–22
Standard mayfly, stonefly, and caddis nymphs: Size 10–14 - Larger nymphs and wet flies: Size 6–8
Heavier hooks (2X or 3X heavy wire) help nymphs sink faster, while lighter hooks keep emergers in the surface film. - Different nymph styles require curved, straight, or long-shank hooks to best match the natural insects they imitate.
Streamer and Large Fly Hook Sizes
Streamers and large baitfish imitations require strong, durable hooks that can handle aggressive strikes.
- Standard trout and bass streamers: Size 4–10
- Large articulated streamers: Size 2–6
- Saltwater and predator flies: 1/0 to 6/0.
- Hook strength considerations: Predator flies demand 2X or 3X strong wire hooks to prevent opening or even breaking under pressure.
Matching Hook Size to Target Species
Different fish species have unique feeding behaviors and mouth structures, influencing the best hook sizes for each.
- Trout – Size 10–24 for dry flies, nymphs, and emergers; Size 4–8 for streamers.
- Bass – Size 2–10 for poppers, streamers, and crawfish patterns.
- Pike & Musky – 3/0 and larger for oversized streamers and articulated flies.
- Salmon & Steelhead – Size 2–8 for nymphs and wet flies; 1/0 and up for large streamers.
- Saltwater Species – Size 1–6 for bonefish and redfish, 2/0 and larger for tarpon, GTs, and stripers.
Some fish, like rainbow trout and panfish, prefer smaller flies, while aggressive predators like bass and pike are drawn to larger baitfish imitations.
Choosing the right hook size is all about matching your gear to the conditions and the fish you're targeting. Always consider the reason behind your selection—whether it’s imitating a natural insect, controlling sink rate, or achieving the perfect dry fly drift. For more useful tips, check out our fly tying resources page.