Understanding Fly Fishing Hook Sizes
Fly fishing hook sizes follow two numbering systems. Sizes #1–#24 use an inverse scale — the larger the number, the smaller the hook. Sizes 1/0–20/0 (aught sizes) increase with the number — the larger the number, the bigger the hook.
A #22 hook is tiny (about 6mm) and perfect for midges, while a #2/0 hook is large (about 30mm) and built for pike and tarpon. The right size depends on your target species, the insects you're imitating, and the water conditions.
Rule of thumb: Match your hook size to the natural insects in the water. Clear water and finicky fish call for smaller hooks (#14–#20). Aggressive predators and murky water favour larger patterns (#2–#8).
Complete Hook Size Chart
This chart covers the most common fly fishing hook sizes, their typical applications, and the species they're best suited for.
| Hook Size | Approx. Length | Best For | Target Species |
|---|---|---|---|
| #24 – #20 | 4–7 mm | Micro midges, tiny dries | Trout (selective stillwater) |
| #18 – #14 | 7–9 mm | Standard dry flies, small nymphs | Trout, grayling, panfish |
| #12 – #10 | 9–12 mm | General-purpose dries, wet flies, nymphs | Trout, bass, perch, carp |
| #8 – #6 | 12–16 mm | Large dry flies, streamers, poppers, buzzers | Trout, bass, chub, pike (small) |
| #4 – #2 | 16–22 mm | Big streamers, muddlers, large nymphs | Bass, pike, carp, salmon |
| #1 – #1/0 | 22–28 mm | Predator streamers, saltwater flies | Striped bass, snook, salmon, pike |
| #2/0 – #6/0 | 28–44 mm | Large predator flies, saltwater patterns | Pike, musky, tarpon, permit, GT |
| #8/0 – #10/0 | 44–60 mm | Big game saltwater flies | Tuna, sharks, sailfish |
Quick Reference by Fly Type
Hook Sizes by Species
Each target species has a preferred hook size range. Here's a quick guide to help you choose the right hook for your next session.
Trout
Bass
Pike
Salmon
Saltwater
Panfish
Grayling
Carp
Hook Sizes by Water Type
| Water Type | Recommended Sizes | Strategy |
|---|---|---|
| Clear Stillwater | #14 – #20 | Finesse approach — small, precise patterns, light tippet |
| Stained Stillwater | #10 – #16 | Slightly larger nymphs and buzzers for visibility |
| Rivers (Freestone) | #10 – #18 | Match local hatches, general-purpose dries and nymphs |
| Rivers (Spring Creek) | #14 – #20 | Technical fishing — small dries, delicate presentations |
| Saltwater Flats | #1/0 – #6/0 | Shrimp, crab, baitfish imitations on heavy tippet |
| Coastal / Surf | #4/0 – #8/0 | Large, buoyant patterns for predators in waves |
| Lakes / Reservoirs | #6 – #14 | Streamers, lures, buzzer rigs for deeper fish |
Expert Tips for Choosing Hook Sizes
Match the hatch: Always observe the natural insects in the water first. If you see size #16 Blue-Winged Olives, tie on a #16 dry fly — not a #12.
Hook weight matters: Larger hooks sink faster. If you need a nymph to drift naturally, choose a lighter wire hook. For deep nymphing, use a tungsten bead on a #14–#16.
Barbless vs. barbed: Barbless hooks (#12–#18 range) are required on many catch-and-release waters. They also make unhooking faster and reduce fish injury.
Hook quality: Always use chemically sharpened, high-carbon steel hooks. Premium hooks from Kumho, Mustad, TMC, and Tiemco hold their point longer and penetrate better.
Frequently Asked Questions
For trout dry flies, use hook sizes #8–#20. Smaller sizes (#14–#20) work best for clear water and selective fish, while #8–#12 are ideal for larger general-purpose dry flies. Adams, Royal Wulff, and Elk Hair Caddis patterns are commonly tied in the #10–#16 range.
For largemouth and smallmouth bass, use hook sizes #2–#8 for streamers and poppers. Larger hooks (#1/0–#2/0) work for big bass patterns in heavy cover. Clouser Minnows and Deceiver patterns are staples in the #2–#6 range.
Pike flies require large, strong hooks — typically #1/0 to #8. Pike have hard mouths and sharp teeth, so use heavy-gauge, corrosion-resistant hooks. Always pair pike flies with a wire or heavy fluorocarbon leader.
Hook sizes use two numbering systems: #1–#24 (larger number = smaller hook) and 1/0–20/0 (larger number = larger hook). A #12 hook is small (trout size, ~9mm), while a #12/0 is enormous (big game saltwater size, ~60mm+). They are completely different hooks.
Nymphs typically use hook sizes #8–#18. Pheasant Tail Nymphs and Hare's Ears are commonly tied on #10–#16, while smaller midge nymphs use #16–#18. Tungsten bead heads add weight for getting nymphs down to the strike zone quickly.
Saltwater flies generally use #1/0 to #6/0 hooks. Bonefish and permit patterns (#2/0–#4/0) are smaller than tarpon and GT patterns (#4/0–#6/0). Always use corrosion-resistant, stainless steel or nickel-plated hooks for saltwater use.