Hook sizes run backwards below 1/0 — a size 8 is smaller than a size 2 — which trips up everyone at first. Here is the whole range, with typical gaps and what each size is actually used for.
| Size | Typical gap (mm) | Typical use | Line range |
|---|---|---|---|
| #16 | 4.0 | Small dry flies, midge patterns | 5X–7X tippet |
| #14 | 4.6 | Trout dry flies, small nymphs | 5X–6X tippet |
| #12 | 5.3 | General trout flies, panfish with small baits | 4X–5X tippet |
| #10 | 6.0 | Wet flies, crappie jigs, small bait hooks | 4 lb |
| #8 | 6.9 | Bait hooks for panfish and trout, small soft plastics | 4–6 lb |
| #6 | 8.0 | Trout bait, walleye jigs, small bass plastics | 6–8 lb |
| #4 | 9.2 | Bass plastics, catfish for eating-size fish | 8–12 lb |
| #2 | 10.7 | Bass jigs and worms, walleye rigs | 8–12 lb |
| #1 | 11.6 | Large bass plastics, inshore bait | 10–15 lb |
| 1/0 | 12.7 | Bass jigs, swimbaits, circle hooks for channel cats | 12–20 lb |
| 2/0 | 14.0 | Largemouth plastics, live bait for stripers | 15–25 lb |
| 3/0 | 15.4 | Topwater and swimbaits, pike leaders | 20–30 lb |
| 4/0 | 17.0 | Pike and muskie, big circle hooks for blues | 25–40 lb |
| 5/0 | 18.7 | Large pike baits, inshore and nearshore bait | 30–50 lb |
| 6/0 | 20.5 | Muskie, striper, big catfish rigs | 40–65 lb |
| 7/0 | 22.6 | Big game live bait, large muskie | 50–80 lb |
| 8/0 | 24.9 | Flathead catfish, shark, large saltwater bait | 65–100 lb |
Gaps are typical values. Hook sizing is not standardised between manufacturers — a 2/0 from one brand is not identical to a 2/0 from another — so treat these as a starting reference, not a spec sheet.
Below 1/0 the scale counts down as the hook gets bigger: a size 8 is smaller than a size 2, and a size 16 is smaller still. At size 1 the system switches to "aught" sizes written as 1/0, 2/0, 3/0 and so on, and there the number counts up as the hook gets bigger.
So the order runs 16 → 14 → 12 → … → 2 → 1 → 1/0 → 2/0 → 3/0. The jump from 1 to 1/0 is where the direction reverses. Once you have seen it written out, it stops being confusing.
The hook has to fit the bait first and the fish second. A hook too large for the bait kills its action and gets ignored; too small and you gut-hook fish.
Small bait, small fish: size 8 to 4. Nightcrawler or leech: size 4 to 1. Minnows and cut bait: 1/0 to 4/0. Large live bait: 5/0 and up.
Circle hooks need to be about one size larger than the J-hook you would use for the same bait, because they must be able to slide to the corner of the mouth to set. They also gut-hook far fewer fish, which matters if you release what you catch.
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Hook size follows bait size and target species. The hook size selector narrows it down interactively, the explanation of hook numbering clears up why bigger numbers mean smaller hooks, and the species size chart shows the fish you are aiming at.
No, it is smaller. Below 1/0 the numbers count down as hooks get larger, so size 8 is smaller than size 6, and both are smaller than size 2. The direction reverses at 1/0, where bigger numbers mean bigger hooks.
It is pronounced "one aught" and it is the size immediately larger than a size 1 hook. From there the scale continues 2/0, 3/0 and so on, with the number increasing as the hook gets bigger.
No. Hook sizing is not standardised across manufacturers, so a 2/0 from one brand can differ noticeably in gap and overall length from another. The charts are typical values; if a precise gap matters, check the brand’s own specification.
Usually yes, about one size up from the J-hook you would use for the same bait. A circle hook must be able to slide clear to the corner of the mouth to set properly, and a hook that is too small cannot do that.
Sizes 2 to 4/0 cover most bass fishing depending on the bait. Small finesse plastics want a size 2 or 1, a standard worm wants 2/0 to 3/0, and large swimbaits and topwaters want 3/0 to 4/0.
Hook Size Selector · Hook sizes explained · Best catfish rig · Best bass lures
Hook Size Selector · Knot Strength Calculator · Lure Weight Calculator
Charts on the same subject: Fishing Line Strength Chart · Fishing Knot Strength Chart · Lure Color Chart
Also worth reading: Split shot sizes chart
Accuracy note: results are calculated from general reference values rather than a physical test of your equipment. Follow the guidance that ships with your gear whenever the two disagree. TackleCalc is independent and is not endorsed by any manufacturer.