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How are Fishing Hooks Measured?

Different size and type of fishing hooks.

A few days ago we received a question about which hook number to choose for each species and how fishing hooks are measured. There is no homologation in the numbering and measurement of the hooks. Although, as a general rule, many manufacturers are guided by numbering in decreasing order to the size or measurement.

However, using this criterion is not universal. The fishing hooks are measured according to manufacturers. That is why you will almost always see the surname of the manufacturer of the hook or always the modality of it.

The measurement of the fishing hook is important to the sport of fishing. The size is determined by a specific formula based on the distance and length between the shaft and shank. When the number is bigger, the hook size is smaller. The size increases from 1/0 to 2/0 and continues in that same format.

The Different Types

The fishing hook is the most basic element for fishing and perhaps also the most important. It is a piece of metal of little value without all the rest of the sophisticated equipment combined for its use. Without a suitable hook and appropriate fishing rod, you will have difficulty catching any fish.

There are many different types of hooks and, like everything in life, there is no type of hook that is perfect for any variety of fishing. Each type of hook has its advantages and disadvantages, and that is why it is better to be informed on the measurements to ensure the best catches.

Characteristics of the Hook: How They Affect Catches

DAMIDEL 200Pcs/Box(Size:10/0. to.1/0 Strong Octopus Fishing Hooks, Forged Steel/Barded Design, Off-Set Point/Closed Eye, Strong/Sturdy, 10/0 8/0 6/0 5/0 4/0 3/0 2/0 1/0 Mixed Packaging

All fishing hooks share a similar shape, at least as far as their ends (head and tip) are concerned. The parts that have undergone the most innovation over the years have been the curvature of the fishing hooks. Let’s take a closer look at the characteristics of each of the parts of a fishing hook.

Beyond choosing between a single, double or triple hook to fish, it is better to start by knowing the elements and measurements of the fishing hook to make mature decisions about the choice to make when buying a hook.

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Many times, when it comes to equipping ourselves, we do not know how to interpret the value of things and we only look at the price and not the various features. In this section, we will talk about the parts of a fishing hook to know, and the features to look for.

Hook Curve

A man holding fishing hooks with different sizes.

One of the main characteristics of a fishing hook is its curvature. These are mainly curved but can vary in the amplitude of the opening. The greater the curvature, the easier it is to hook the fish in the bite, but this has its counterpart in that it will also be easier for the catch to get rid of the hook.

Another factor that affects the curvature is the force of the hook. The greater the curve, the more easily the hook will deform due to the angle at which the fish exerts the force when pulling. Straight hooks are therefore more recommended for more aggressive fish that tend to escape once they have bitten the bait, but on the other hand, it is more complicated that they get hooked.

The Numbering

A man holding a box of fishing hooks.

The numbering of the sizes for hooks may seem somewhat strange, but once we understand it it is very simple. Basically, the numbering divides between the large hooks and the small hooks with the ‘0’ in the middle, although the size ‘0’ does not exist.

Small hooks have a simple numbering that grows as the size decreases, with the hook ‘5’ being less than the number ‘3’. On the other hand, large hooks have a number followed by ‘/0’ and the higher this number the larger the hook. Therefore, a ‘3/0’ hook will be smaller than an ‘8/0’ one.

Contrary to what intuition may tell us, the size of fishing hooks is listed, giving the largest number to the smallest hooks. That is, the smallest hook has the largest numbering, while hooks with numberings closest to 0 are larger. The hooks for fishing large fish, that is, the largest hooks, have different numbers.

These are numbered in this way ‘n / o’ where ‘n’ increases as the size of the fishing hook are higher. Thus, currently, the largest sportfishing hook that exists is the 20/o, while the smallest would be the 32.

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However, if things weren’t complicated enough already, our Japanese friends decided to have their own way of numbering fishing hooks. Luckily, the Japanese are known for simplifying things a lot. Therefore, the Japanese size designation assigns the number 1 to the larger fishing hook and then the numbers decrease as the hooks get smaller.

It must be taken into account when buying a hook that not all brands use the same size for each measurement, although luckily for buyers, this is changing and increasingly tends to the standardization of hook sizes.

Length of Rod or Stem

A fishing rods displayed on a store.

Typically, brands sell hooks with 3 different lengths of rod: long, standard and short. Although certain marks also define the length of the rod with a multiplier, being x1 the standard length and x3 three times that length. As in almost everything, each length has its advantages and disadvantages.

Hooks with short stems cause fewer tangle problems when we use more than one hook, and also tend to hook less when we throw in complicated places. Hooks with longer rod length have their advantage in securing those elusive catches that tend to unhook. Of course, as always, everything will depend on the bait we use and there is no better advisor than experience.

Meet the Hooks

When choosing the hook, you will have to rely on its actual size and not on a number that can lead to misunderstanding. All brands show us their physical size, even if you buy them online you should check. You may be buying a hook of 18 and for another brand, it is equal to 14. It is normal to have them between size 12/0 for those over 26, which are the smallest.

The Point

A black fishing hook with a single line.

The point is the sharp part of the hook of variable length whose end penetrates the jaw of the fish. It has a lock called DEATH that largely prevents the catch from being released. It can be located on the plane of the hook or slightly inclined. In the first case, the nailing is more effective with soft-mouthed fish, and in the second in fish with a hard mouth and palate.

The tip can be straight or curved (eagle claw). The straight tip makes better contact with the fish’s mouth, but it nails with less force than the curved one. That is why the straight is better for soft-mouthed fish such as catfish, and the curved or eagle claw for fish with hard mandivula such as dorado. A small one penetrates better and a large one retains capture better.

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The Body

A fishing hook with 3 point.

The diameter of the body of the hook determines the effort it can withstand, and depends on the piece to be captured, the heavier, the larger the diameter the hook should have. A larger body diameter increases the weight of the hook and decreases its penetration capacity, so it should not be applied to light catches.

The Mouth

It is the measured opening between the tip and the leg of the hook. Define its size for the same hook model. Two hooks of different designs and of the same size in the scale can have different mouths. The correct choice of hook numbering depends on the species and the size of the hook, but this can vary over a wide range. The wisdom of choice consists in not exceeding one way or another.

Size Scale

The size scale assigns a number to the hook according to its dimensions. There are several scales or ways to define the size of the hooks. Sizes are as small as #30 and as large as #20/0.


A person holding a fish with hook on the mouth.

For a correct choice in size and measurement, will depend on the type of hook and its features. We must also consider the factors to be taken into account according to the species sought and the bait to be used. The hook is the most important part of fishing equipment and largely defines our successes or failures at the time of fishing.

Finally, we must not forget the thickness of the hook since the resistance is very determined by this aspect. As we increase the size of the hook, the thickness grows, with great importance in the upper sizes for large predators. Once we choose a hook size and find we are not getting any catches, it may be time to change the hook to a smaller one.