What Size Flag for a 20, 25 or 30 ft Flagpole? The Full Chart, 15 to 80 ft, and What Oversizing Does

The short answer: the flag's length should be about one quarter to one third of the pole's exposed height. On a 20 ft pole that's a 3x5 or a 4x6. On a 25 ft pole, a 4x6 or a 5x8. On a 30 ft pole, a 5x8, with a 6x10 on an open site. Above that, a 35 ft pole takes a 6x10, a 40 ft pole an 8x12, and a 50 ft pole a 10x15.

That's the chart answer, and it's a good one. But there is a second number that matters more than any chart, and most people never look for it: the flag size the pole was rated with. Every commercial aluminum pole has a wind rating calculated with a flag of a certain size flying from it. Put a bigger flag up and that rating no longer describes your pole. This article covers both: the general chart, how the rule works, and how to find the flag your particular pole was built for.

The full chart, 15 to 80 ft

This is the general guide America's Dealers and Distributors (ADD) publishes in its flag size guide. The first column is the pole's exposed height, meaning the part above ground, not the overall length that includes the section buried in the foundation.

The prices are ADD's published list prices for the pole only, satin finish, one pole, as checked in October 2026. They're there to show how much is riding on the pole, which is part of why the flag on top deserves a minute of thought.

Other flag companies publish their own charts, and they land in the same neighborhood with small differences at each height. USA Flag Co.'s guide gives a "standard" and a "maximum" size for each height, with 3x5 as its standard for a 20 ft pole. Colonial Flag's chart gives a pair of sizes per height and adds advice on wall-mounted poles. Eder Flag's own guide walks through the arithmetic for homes and businesses. The differences between charts come from the fact that flags are sold in fixed sizes, so every chart is picking the nearest stock size to the same rule. Where two charts disagree by one size, both sizes are usually fine on a well-rated pole.

How the 1/4 to 1/3 rule works

The rule is about the flag's length, which flag makers call the fly: the long side, the one that streams out from the pole. The short side, against the pole, is the hoist.

Take the pole's exposed height and multiply by 0.25 and by 0.33. That's your range for the fly.

• 15 ft pole: 3.75 to 5 ft. A 3x5 has a 5 ft fly, right at the top of the range.
• 20 ft pole: 5 to 6.6 ft. A 3x5 (5 ft fly) and a 4x6 (6 ft fly) both fit.
• 25 ft pole: 6.25 to 8.25 ft. A 4x6 sits just under, a 5x8 sits inside.
• 30 ft pole: 7.5 to 10 ft. A 5x8 and a 6x10 both fit.
• 40 ft pole: 10 to 13.3 ft. An 8x12 fits.
• 50 ft pole: 12.5 to 16.5 ft. A 10x15 fits.
• 60 ft pole: 15 to 20 ft. A 12x18 fits.

Above 60 ft the standard sizes jump in bigger steps (12x18, then 15x25, then 20x30), so the charts pick the nearest stock size rather than one that lands neatly inside the range. On a pole that tall, the rated flag size for that specific pole is the figure to go by, and the next sections explain why.

Most commercial installations sit near the middle of the range. Toward the low end, the flag lasts longer and the pole works less hard. Toward the high end, the flag reads better from a distance.

The number that matters more than the chart: your pole's rated flag

Here is the part worth slowing down for.

Eder, which makes the aluminum flagpoles ADD sells, publishes a recommended flag for every pole it makes. ADD lists that recommended flag beside each model on its flagpole price list and in its pole finder. A few examples from ADD's site:

• ECSS15 and ECSS20 (15 and 20 ft): 3x5
• ECSS25 and ECX25 (25 ft): 4x6
• 30 ft poles: 5x8

Notice that the model-specific figure can be a size smaller than the general chart. ADD's general chart says 4x6 for a 20 ft pole, while the ECSS20 lists a 3x5. That isn't a contradiction. The general chart describes what looks right on a 20 ft pole. The model figure describes what that particular pole, with its particular wall thickness and diameter, was rated to carry. When the two differ, follow the pole.

The reason is the wind rating. ADD makes a point of showing the flag-flying wind rating on every pole, not just the bare-pole figure, because a flag pulls far harder on a pole than bare metal does. That flag-flying rating is worked out with the recommended flag on the pole. Fly a bigger flag and the real load goes up while the number on the spec sheet stays the same. Eder publishes its flag-flying ratings as a steady wind with a 1.3 gust factor, per ANSI/NAAMM FL 1001-07, and that calculation assumes a specific flag area.

If you're not sure what pole you have, look for a tag or stamp near the base, check the paperwork from when it went in, or send a photo to whoever supplied it.

What oversizing actually does

A flag one size up on a pole with plenty of margin isn't a disaster. A flag two sizes up, or one size up on a pole already near its limit, causes real problems. In rough order of how soon you'll notice them:

1. The flag wears out faster. A big flag on a short pole whips harder. The fly end, the part farthest from the pole, takes the beating and frays first. ADD's guide notes that a flag flying at the edge of its tolerance frays at the fly end in months rather than years.
2. The hardware wears faster. The halyard (the rope), the snap hooks and the truck at the top all carry the flag's pull. More flag means more pull on every one of them, all day.
3. The pole works harder. The flag's pull acts at the very top of the pole, which is the worst place for a load to act. On a pole that was already close to its rating for the address, an oversized flag can turn a comfortable margin into no margin.
4. The warranty can be affected. ADD's guide is plain about this: oversizing loads the pole and can void the warranty. A warranty is written around the pole being used as rated, and the rated flag is part of that.

There's also the plain visual problem. An oversized flag on a light day droops and wraps around the shaft. A flag that fits the pole flies cleanly more often.

And undersizing?

Undersizing is safe, just underwhelming. A 3x5 on a 35 ft commercial pole reads like a postage stamp from the street. It isn't a structural concern, and some owners in very windy places choose to go one size down on purpose because the flag lasts longer. That's a reasonable call. Going down more than one size usually looks odd enough that people notice.

Wind, water and fabric: when to adjust

Size and fabric work together. ADD sells American flags in two fabrics, and its flag pages lay out the choice in plain terms:

ADD's short version is a good test: how close are you to water? Salt air and steady wind are what wear a flag out, and the end of the flag goes first. Near water, polyester. Inland and sheltered, nylon.

On a windy site, a heavier flag at the recommended size usually solves fraying better than a smaller flag in a lighter fabric. If you're replacing flags every few months, switch fabric before you drop a size. ADD's guide makes the same point: moving from nylon to polyester usually fixes a flag that shreds too fast. It also suggests buying two flags and rotating them, which roughly doubles the life of both and means you're never flying a worn flag while you wait for a new one.

Flying two flags on one pole

A state flag, a POW-MIA flag or a service flag under the American flag is common, especially at schools, fire companies and veterans posts. Two things to watch:

• The American flag goes on top, and by convention the flag under it is the same size or smaller. USA Flag Co.'s guide suggests the second flag go one size down, for example a 3x5 American flag over a 2x3 state flag, both for looks and to keep the weight down.
• Count both flags in the load. The pole doesn't care which flag is which. Two flags mean more area on the halyard and more pull at the top. If you plan to fly two flags every day, say so when you buy the pole. ADD lists multiple flags on one pole as a normal requirement on military and government jobs, where it's specified up front so the pole is sized for it.

ADD sells all 50 state flags, each sewn to its own state's spec, and military and service flags for every branch plus POW-MIA, so the second flag can be ordered with the first.

Wall brackets and porch poles

A house-mounted bracket with a short pole is its own case. ADD's flag page puts it simply: a bracket on the porch flies a 2x3 or a 3x5. Measure from the bracket to the nearest obstacle (a gutter, a light, the walkway) and make sure the flag clears it when it hangs straight down on a calm day.

Giant flags on 100 to 150 ft steel poles

At the top of the range, chart-reading stops being useful. ADD's steel poles from 100 to 150 ft are made in the USA and sized to the wind and soil at the site, so each one is priced and engineered individually. Its Mega Poles page says a pole that tall flies a large flag, raised on a winch, and that ADD recommends the flag and the halyard with the pole. The recommended flag size is one of the line items ADD lists in the price for each steel height, alongside the rated wind speed with a flag flying. In other words, on a giant pole the flag size is part of the engineering, not something picked afterwards.

ADD's flag shop carries twenty sizes, from 2x3 up to 50x80, so the biggest flags exist. Whether a given pole should fly one is a question for the pole's numbers.

A quick checklist before you order

• [ ] Measure the pole's exposed height, ground to the top of the truck, not the overall length.
• [ ] Look up the model's recommended flag on the tag, the paperwork or the seller's listing. If it's smaller than the chart, use the pole's figure.
• [ ] Ask how windy and how close to water the site is. Near water or on an open site, choose heavy-duty polyester.
• [ ] Decide whether you'll fly one flag or two. If two, size the second one the same or smaller and count both in the load.
• [ ] If you're replacing an old flag, measure it rather than reordering the same size. It may have been wrong all along.
• [ ] Consider buying two and rotating them.

How ADD handles the flag question

Most of the time the flag question comes up as a side note on a pole quote, and that's how ADD treats it: the recommended flag is already on the page next to each pole, so a buyer sees the pole, its price, its flag-flying wind rating and the flag it was rated with in one place. The pole finder on ADD's site does the same thing in three quick questions: it names the pole, the flag and the price together.

When someone just wants a flag for a pole they already have, ADD's advice is the same as its guide: give the pole height and let the size follow from it, and if you.re unsure, ask. Its flag page says it plainly: "We will tell you the right size if you ask." One person reads each request and replies, usually the same business day, and if the answer is a smaller or cheaper flag than the one you had in mind, that's the answer you'll get. ADD's own line on the subject: "We would rather spend fifteen minutes on the phone than sell you the wrong pole." The same goes for the flag.

On the practical side, every flag ADD sells is sewn in the USA by American flag makers, stripes stitched and stars embroidered from 3x5 up, with a canvas header and solid brass grommets. Shipping is free on every order, and flags usually leave the mill in two to three business days. Through the winter, ADD is running a buy 2, get 1 free sale on flags only (the lowest-priced flag in each three is free, and flags bought during the sale are final sale). It doesn't apply to flagpoles or installation. If you're following the rotate-two-flags advice above, the timing works out.

The safest habit is the one at the top of this article: the chart tells you what looks right, and the pole tells you what it can carry. When they agree, order with confidence. When they don't, go with the pole.