4 Weight vs 5 Weight Fly Rod: Which Should You Choose?

Asking which is better, a four weight, or a five weight fly rod is akin to asking whether a .22 rimfire is better than a .30-06 centerfire rifle.

The answer is always yes, and no. It’s not exactly apples and oranges, but a four weight fly rod has benefits a five weight rod does not, and of course, the reverse is also true.

Before we delve into the difference between a four and a five weight fly rod, and the relative merits, and demerits of each, let’s take a look at how fly rods are categorized by weight rating.

The Fly Rod Weight Scale

Fly rods are weighted on a scale of 0 to 15. An apt, but maybe a little extreme analogy is a wet spaghetti noodle on the 0 side and a piece of steel rebar on the 15 end.

What it really means is a whippy, easy to bend, weak rod with a 0 rating, and a stiff, powerful rod, with no flexibility at the 15 metric.

The secret to this scale, and how to use it is choosing something in the middle. It’s another classic example of the “Goldilocks Principal” ie: not too hard, not too soft, but just right.

Fly rods are traditionally broken down into ranges, 0-3, 4-6, 7-10, and 11-15. What that means to you is a flexible, moderate, hard, and heavy resistance.

With each step up the scale, the rod becomes stronger, but it also loses sensitivity. Since fly fishermen require a sensitive touch to set the hook when a trout or pan fish hits the fly, the heavier the rod, the lesser the chance of feeling that strike.

The only reason people choose the higher numbered rods is that they are vastly superior in casting distance and work well in very windy conditions.

The length of cast is possible because of the greater stiffness of the rod. That increased strength comes at a price, it reduces the accuracy you can achieve.

This brings us to the number four and number five weight rods. These are the two most popular sized fly rods for a reason.

They have enough strength to cast good distances, they can be incredibly accurate in placing a fly in the hands of a skilled angler, and they have the soft, sensitive touch it takes to feel the lightest strike on that dry fly floating above a hungry rainbow trout.

Rod Weights and Line Weight

4 Weight vs 5 Weight Fly Rod

Fly rods are attuned to work with specific weight fly line. As in rod weights, the lower the number, the lighter the line. Fly rods work with line weights with the same number, but also work well with line weights one number below or one number above.

What that means is a four weight rod works best in normal conditions with a four weight line, but they also work well with either a three or a five weight line.

A three weight line on a four weight rod won’t cast as far, but is easier to feel a strike with. A five weight line will cast farther and enhances a four weight rod’s versatility by allowing the angler to compensate for windy conditions.

A five weight rod works the same way. It’s best with the preferred five weight line that many fly fishing anglers prefer, but it does a good job with a four or six weight line as well.

This variance in light weight allows a skilled, educated angler the chance to compensate for conditions that would otherwise make fishing difficult.

Which is Better a Four or a Five Weight Rod?

Here is the stickler, which one is best? The answer is both, neither, and maybe one or possibly the other.

That’s not much of an answer, and sales totals indicate that the number five weight rod far exceeds the number four weight in total sales, but sales don’t mean the five weight is the best rod for all instances.

The four weight rod

If you’re after brook trout, on a small stream, full of tight angles, small pools, and heavy underbrush, you can’t beat a four weight rod.

It allows you the accuracy to put a fly just inches from a target, lets the lighter line work its magic in the swirling water of a small stream, and has the sensitivity to feel those incredibly light strikes that an annoyed, but not hungry brookie can make on a dry fly as it floats by.

On top of the physical attributes, the fun of a four weight rod is hard to beat. It will bend over, with even smaller, hard fighting fish, sending droplets of water gleaming into the sunlight like pearls on an ocean shore.

Those old images of anglers with a rod bent double in one hand and a hand net in the other scooping down to pick up a trout are what you can expect in a four weight rod.

The five weight rod

4 Weight vs 5 Weight Fly Rod

Versatility is the key word when it comes to a five weight rod. With five weight line you’ve got a rod that is almost as easy to cast as a lighter four weight version, but it has the extra strength and stiffness to handle the epic battle with big trout.

Nothing short of an enraged largemouth bass hits with the ferocity of a rainbow trout. If you’re working water with the potential of getting strikes from rainbow trout above 20 inches in length, you’ll quickly appreciate the handling a five weight rod can offer.

As those tail dancing, wildly thrashing rainbows break the surface and flash in the air they often spit out a fly on a lower weight rod.

A five weight rod will allow you to maintain enough pressure on the trout as it leaps but not so much that you’d snap your leader from pulling too hard. It’s Goldilocks again, only this time it’s measured in the controlled resistance a five weight rod can offer in larger fish.

A number five rod with a number four line offers close performance to a straight up number four rod. The sensitivity the lighter line offers compensates for the shorter casts.

A lighter line on a number five rod drifted into prospective holes on a slow-moving river is a thing of beauty. Just watch the fly float lazily down the river, skirting around each eddy and back swell on its race to destiny with a hidden pan fish, brown or rainbow.

A number five rod with a number six line is good way to make the best of lousy conditions on the water. You work against your obligations to get a free day on your favorite trout stream only to find the weather decided not to cooperate.

Wet, cloudy conditions aren’t the enemy. A low hanging front with a light rain often produces the best trout fishing conditions you can find. Select a fly to match the conditions and let it do the work for you.

Trout, bass, crappie and sunfish all feed more actively as a low pressure front moves in. Let your rod do the magic with a five weight line and have some fun.

It’s the high pressure systems that can ruin your day. The trout will still hit on dry flies, streamers and egg sacks presented correctly, it’s just difficult to present them since high pressure usually means wind. Wind is the enemy of the fly fisherman since it swats, bats, batters and inhibits the presentation of the fly.

A light line is nearly impossible to cast in winds above 20 miles per hour. If you’re fly fishing in Wyoming or Montana, arguably the best trout fisheries on earth, you’re going to encounter wind, wind that sometimes blows at 30 to 40 miles per hour suddenly with no warning.

A heavier weight line, perhaps a six weight line, on your five weigh rod lets you battle this wind effectively.

With a little practice in letting the wind work for you rather than working against it, you can still have some fun catching fish in spite of the overly gusty conditions.

Cast your line with just one or two whips from your five weight rod, let the heavier line do the work and get your fly and leader into position and then let the water carry the fly. It’s all about presentation no matter the conditions.


Fly fishing is one of the greatest joys an angler can have on the water.

If it’s a small stream, covered by thick willows, you’re not going to be able to make long flowing casts, but you’ll need to present your fly accurately or you’ll spend the day wading in the water, scaring away fish as you trudged down the bank continuously through the brush to get your fly out of the brush growing nearby.

When you find yourself in these conditions, choose the lighter four weight rod, its accuracy is unsurpassed.

If on the other hand, you’re going to cover a lot of water in varied conditions and may catch a lot of different trout, then go with the five weight rod. It’s popular for a reason, and that reason is versatility.

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