How Much Text Should an Ad Have

Everyone in advertising repeats that less is more. The counter-argument is obvious: if the ad never says what you sell, nobody can want it. Both sides are right, in different places, and the deciding number is measurable.

That number is how long somebody actually looks at your ad. It has been measured with eye trackers on real roads and real screens, and it sets a hard limit on how many words you get.

A driver looks at a billboard for a third of a second

The US Federal Highway Administration put eye trackers in cars and drove 55 people past real billboards in Reading, Pennsylvania and Richmond, Virginia.

• The average look at a digital billboard lasted 0.379 of a second, and at a printed billboard 0.335 of a second. That is a single glance, and it is about as long as the average glance drivers gave the road ahead.
• The longest single look at any billboard in the whole study was 1.335 seconds. Nobody stared. Looks longer than one second were rare events.
• Adding up every glance a driver gave one billboard, the total came to between 0.674 and 1.386 seconds. Drivers took two or three quick flicks rather than one long look, so that total is the real amount of time an ad gets.
• A second field study using eye trackers in traffic found drivers gave advertising just 1.2% of all their glances, lasting 0.5 to 0.75 of a second each. Two independent studies, and both land under one second.

A driver has time to read only three to five words

Turning that time into a word count needs one more number, and it has also been measured properly. A 2019 review of 190 studies covering 18,573 people put adult silent reading at 238 words a minute, which is just under four words a second.

• A single 0.335 second glance at a printed billboard is long enough for one or two words. That is the whole reason a billboard with a paragraph on it fails. The driver never had time to reach the end of the first line.
• The full 0.674 to 1.386 seconds a driver spends on one billboard is long enough to read three to five words. Not a sentence, not a tagline plus a phone number plus a web address. Three to five words.
• A display banner that somebody does look at gets 1.3 seconds on average, which is long enough for about five words. Measured by the eye-tracking firm Lumen Research across its panel.
• Reading is what takes the time, and recognising a familiar logo takes almost none of it. A logo is taken in at a glance rather than read left to right, which is why the brand mark is the one element that always fits.

The seven word billboard rule rests on a misread study

Almost every billboard guide says seven words or fewer, and almost every one of them credits the same source: George Miller's 1956 paper on the magical number seven. That is not what the paper says.

• George Miller said his own magical number seven had nothing to do with reading. His words: the point was that seven was a limit for telling apart simple signals like pitch and brightness, and a limit for immediate recall, "neither of which has anything to do with a person's capacity to comprehend printed text".
• The real working memory limit is now put at three or four items, not seven. So even the number being borrowed has moved since 1956.
• The seven word advice lands near the right size by luck, and looking time is the real reason. A third of a second at four words a second comes out at three to five words, and that reasoning survives scrutiny where the memory story does not.
• The widely quoted claim that six to eight words gives 65% better recall has no traceable source. It appears on billboard company blogs with no study attached, so it is not evidence.

Every ad medium ranked by how many words fit the time

Same arithmetic applied to each place an ad can run. The number of words is the measured looking time multiplied by four words a second.

The top row is the odd one out, and it is where the rest of this article goes. When the reader controls how long they look, the time limit disappears and the advice reverses.

Use Repeat Recorder to time your billboard line out loud

The word limit above is hard to judge while you are staring at a design file, because every line looks short in 200 point type. Saying it out loud puts a real clock on it, and the same 2019 review measured reading aloud at 183 words a minute, so five words takes about 1.6 seconds to say. Repeat Recorder, one of my own apps, is a recorder built around a loop: you speak, it replays what you said, and it records your next attempt.

• Repeat Recorder plays your line back about a second after you say it, so you hear the length rather than guess at it. A line you cannot finish in one breath is also too long for a billboard.
• Repeat Recorder can loop one take as many times as you set, or forever until you stop it. Hearing the same five words over and over is how you find the one word doing no work.
• Repeat Recorder has a fully hands-free mode where speaking starts the recording and stopping replays it. You never touch the screen, so you can run through candidate lines while walking or holding a layout.

Longer ads beat shorter ads whenever the reader can click

To test the less is more claim where clicking is possible, I used a public archive of randomised advertising experiments run by the publisher Upworthy between 2013 and 2015. Each test showed the same article in the same place on the same day and changed only the wording. I kept the 10,592 tests where the picture was identical too, then compared the shortest and longest wording inside each test.

• The shorter wording won only 43.9% of 10,372 randomised tests, and lost 6.4% of the clicks the longer wording got. This is the opposite of less is more, and with 10,372 tests it is not a fluke.
• The bigger the length gap between the two wordings, the worse the shorter one did. Where one wording was at least ten words longer, the shorter one won just 34.9% of the time and lost 18.0% of the clicks.
• Adding one word changed nothing, and adding five words won about 6% more clicks. One extra word measured as exactly nothing, so this is about adding a real amount of information rather than trimming or padding.
• The result held separately in 2013, 2014 and 2015, and held when measured in characters instead of words. Three independent years and a different unit, same direction every time.

Extra words only win when they carry a fact

Length by itself is not what wins, and this is the answer to the whole dilemma. I split the same tests by what the extra words actually added.

• Where the longer wording also added a name, a number, a price or a percentage, it won 57.4% of 7,137 tests and gained 8.1% more clicks. Concrete information is what the reader is paying attention for.
• Where the longer wording added only mood and story words with no new facts, the gain fell to 2.4% and was too small to tell apart from chance. Padding an ad with atmosphere measured as nothing.
• The short ad lost because it said less, not because readers prefer brevity. The short ad was not losing because it was short. It was losing because it had less to say.
• Every word you add has to tell the reader something they did not already know. That is a much more useful rule than a word limit, and it is the one the data actually supports.

Adding words stops helping at about 18 words

More is better, but not without limit. Splitting the same tests by how long the wording already was shows exactly where the gain runs out.

• Under ten words, the longer version gained 16.6% more clicks, the biggest gain measured anywhere in the set. A short ad is where extra words are worth the most.
• Between 13 and 19 words, the gain from going longer had shrunk to about 6.5%. Still real, but less than half what it was at the short end.
• Past 19 words the gain was too small to tell apart from chance. That is where adding more text stops buying anything, so about 18 to 20 words is as far as it is worth going.
• Counting clicks by wording length across every test also peaks at 18 words. The click rate climbed from 0.95% at six words to 1.23% at eighteen, then eased off.

Making every word specific backfires in half of tests

Two Cornell researchers ran the other half of this question on the same archive and published it in Scientific Reports in January 2025. They scored how concrete each wording was, word by word, across 8,977 experiments.

• Where the wording was already vague, making it more concrete raised clicks by 5.5%. Being too vague genuinely costs you, which is the fear the less is more crowd never addresses.
• Where the wording was already concrete, making it more concrete cut clicks by 9.9%. A dry list of specifics reads like a spec sheet and loses to a line that leaves the reader something to find out.
• Half of all real tests, 50.9%, sat on the too-specific side, and only 8.7% were too vague. So in practice the more common mistake is spelling everything out, not being mysterious.
• Adding a few facts to a long line wins, and making every single word a specification loses. The winner is a longer line, mostly ordinary words, holding two or three concrete anchors. The loser is a short line where every word is a specification.

Use Camera to Clipboard to collect billboards you drive past

The best training for this is the billboards you already pass every week, because the ones that work on you are the evidence. The problem is that photos of them stay stranded on your phone. Camera to Clipboard, another of my own apps, puts a photo from your phone straight onto your computer's clipboard, so it is ready to paste the moment you sit down.

• Camera to Clipboard sends the photo to your computer clipboard, so you paste it into a document instead of emailing it to yourself. Building a folder of billboards you actually noticed takes seconds a time rather than a weekly tidy-up.
• Camera to Clipboard pairs your phone to your desktop once and then works over your network. There is no cable and no upload step in the way of a quick capture.
• Pasting the photos side by side is how you count the words in a billboard that worked on you. Most of them will land in the three to five words this article started with, and seeing that yourself is more convincing than being told.

Dense detail hurts attention but elaborate design helps

The most useful study on this separated two things that both get called complexity, and found they pull in opposite directions. It eye-tracked 249 real ads and was published in the Journal of Marketing in 2010.

• Cramming in more detail, more objects and more small elements reduced attention to the brand and made people like the ad less. This is the kind of complexity the less is more advice is really aiming at.
• An elaborate creative idea raised attention to the picture, to the ad as a whole, and to how well people understood it. An ambitious ad is not a cluttered ad, and the study measured them separately to prove it.
• An interesting idea is the one kind of complexity an advertiser actually controls. You cannot buy more looking time, but you can decide whether your idea is interesting.
• Cut the number of things competing on the page, not the ambition of the idea. Fewer separate things competing on the page, with more thought behind the one thing that is left.

Only 35% of display ads are ever actually seen

Before arguing about the words in a banner, it is worth knowing how often anybody looks at one. Lumen Research measures this with eye trackers rather than with delivery reports.

• Only 35% of digital display ads got any looking at all. The other 65% were served, counted and paid for without a human eye reaching them.
• Of the ads that were served, just 9% got more than one second and 4% got more than two seconds. So the five words a banner gets is the good case, not the average case.
• Only about 30% of ads that counted as viewable were actually seen. Viewable is a technical definition about pixels on screen, and it is not the same as looked at.
• Readers avoid banners on purpose, and this was proved with eye tracking back in 2003. People fixated fewer banners than their size and position predicted, meaning they spot an ad in peripheral vision and steer their eyes around it. Only 46.9% could remember seeing any banner at all afterwards.

Billboards now beat display ads for attention

The natural assumption is that billboards stopped working once everybody started staring at their phone. The attention measurements say the reverse, with one caveat worth stating plainly.

• Roughly 2.5 seconds of attention is the point where an ad starts entering memory, and 85% of digital ads fall short of it. That threshold comes from Karen Nelson-Field's attention research.
• About 89% of roadside ads clear that same 2.5 second threshold, against 15% of digital ads. A billboard is a small amount of attention that you reliably get, and a banner is a large amount you usually do not.
• A distinctive brand asset can do the job in 1.5 seconds, which is less time than a billboard already gets. That is a colour, a shape or a character the audience already links to you, working without the name being spelled out.
• The strongest numbers favouring billboards come from companies that sell billboards, so treat the size of the gap as unsettled. A five-year Kantar study reporting 13.3% higher ad awareness for roadside advertising was commissioned by Clear Channel Outdoor, which owns billboards. The direction is echoed by independent eye tracking, the exact multiples are not.

Use Repeat Recorder to rehearse an ad line while driving

Since this article is largely about what you see through a windscreen, the drive itself is usable time. Repeat Recorder, one of my own apps mentioned earlier, has an automatic mode where speaking starts the recording and going quiet replays it, so you never touch the phone.

• Repeat Recorder's automatic mode needs no taps at all, which is what makes it usable with your hands on the wheel. You say a candidate line, it plays back, you say the next one.
• Repeat Recorder saves the takes worth keeping into folders you name yourself. Ten spoken versions of one line, kept together, is a better shortlist than ten typed ones.

Ten ads rewritten to fit the time they actually get

The fix goes in both directions. Roadside and banner ads come down to the number of words there is time for, while ads the reader can click go up.

The three feed rows go the other way, up from four to six words to about sixteen, and every word added carries a number or a name.

Conclusion: how much text an ad should have

Less is more is not a rule about advertising. It is a rule about time, and it only applies where the time is short and fixed.

• Count the looking time, then allow four words a second. That is the whole method.
• A billboard gets three to five words. One glance is 0.335 of a second.
• A display banner gets about five words. Only 35% are looked at at all.
• An ad the reader can click should run to about 18 words. Shorter lost 6.4% of the clicks.
• Add words only when they carry a name, a number or a price. Facts gained 8.1%, mood gained nothing.
• Do not spell out everything in a clickable ad. Over-specific wording lost 9.9%.
• Do not be vague either, because vague wording lost 5.5%. Aim between the two.
• Cut the number of competing elements, not the ambition of the idea. Clutter hurt attention, a strong idea helped it.
• Put your logo on it, because recognising it takes almost no time. A brand mark is taken in at a glance rather than read.
• Ignore the seven word rule and the memory study behind it. Miller said it had nothing to do with reading.