Writing banner copy in three lengths

Banner copy is read in passing and gets very little room, and the same message has to work in a 320×50 and in a 1080×1920. This guide shows how to write it in three lengths, what to cut first when space runs out, and how to phrase offers, legal lines and calls to action.

Write a family, not one headline

A single headline is written for one format: whichever one was on the screen when it was written. Write a family of versions instead, so every format can take the longest one that fits. A complete set has:

• a headline in a short, a medium and a long version
• an optional subline, also in three lengths
• a button label in a short and a long version

Here is what that looks like for Velo Atelier, a fictional bike shop promoting its repair service.

A few rules make a family work:

• The short version carries the whole message. In a 320×50 it stands alone next to the logo and the button. If it only makes sense with the subline, it fails there.
• Every version says the same thing. Each length adds detail, not a new idea, so any mix of lengths in one set reads as one campaign.
• Each length stands on its own. The long headline is a sentence in its own right, not the short one with words attached.

This guide covers the words set on the banner itself. Social platforms add text fields of their own around the image, each with its own limits. Facebook Feed, for instance, suggests a headline of 27 characters, and Instagram Reels primary text of 44.^[1][2] The ad spec pages list them per platform.

Sublines and buttons

The subline supports the headline with a detail or a proof: what is included, where, how fast. It is optional. Many strips and small squares have no room for one, so the headline must never depend on it.

The button names an action. Its short label is one or two words; its long label adds the object.

• Short: “Book”, “Apply”, “Order now”
• Long: “Book a service”, “See the jobs”, “Start a subscription”

320 × 50

300 × 600

What to cut first when space runs out

When the copy does not fit, cut in an order that costs the reader as little as possible:

1. Switch the button to its short label. “Book” and “Book a service” lead to the same page.
2. Move the subline and the headline to shorter versions. The point stays; some detail goes.
3. Drop the optional lines, such as the subline. The landing page can give the detail they carried.

Sizewright fits copy in a real browser, with up to ten attempts per banner, in this order. That is why the short versions matter: they are what the tightest formats will show.

Two things should never be solved by shrinking. Do not set the type smaller than the format allows (Sizewright’s minimum is 4% of the banner’s shorter side, and never less than 10 pixels). And do not squeeze the letter spacing until the words touch. If the short version still does not fit, it needs fewer words, not smaller ones.

Offers and legal lines

An offer is a promise the landing page has to keep, so write it exactly as it applies.

• The value, as it should read: “−20%”, “€89”, “2 for 1”. Large, with nothing else on its line.
• A short caption: “on your first box”, “on every crossing”. It says what the offer applies to.
• The conditions: who qualifies, the minimum order, the end date. If a condition changes what the reader gets, it belongs on the banner or one click away, not hidden.

Meta’s advertising policy checklist warns against “withholding key information to entice someone to click on the ad”, and against “sensationalized or exaggerated language”. Its list of rejection reasons also includes “improper grammar or punctuation”.^[3] Google’s editorial policy rules out “gimmicky” repetition of words and spacing.^[4] None of this needs to be a constraint. Plain, exact copy stays clear of all of it, and it reads better.

In Sizewright, offers, prices, dates and quotes are set exactly as you type them in the brief, and the copy is written around them. The brand kit holds a legal line per language, so the small print is written once per market.

Calls to action that name the action

A good button tells the reader what happens after the click. “Book a service”, “See the jobs” and “Get tickets” each promise a page. “Click here” and “Learn more” promise nothing in particular. Use them only when nothing more specific is true.

• Match the landing page. If the button says “See the jobs”, the click should land on the jobs, not on the home page.
• Use the reader’s verb, not yours. “Book”, “Order”, “Apply”, “Download”: the thing the reader does.
• Keep the button honest. On a banner, the button is a picture, and the whole banner is the link. Meta’s policy rules out images that show “non-existent functionality”, such as a play button that plays nothing.^[3] Google and DV360 reject ads that resemble site warnings or error messages, and DV360 adds dialog boxes.^[5][6]
• One action per banner. The whole banner leads to one page, so a second button would promise something the click cannot deliver.

If you leave the call to action empty in a Sizewright brief, one is suggested from the campaign goal: “Shop the sale” for an offer, “Apply now” for hiring, “Get tickets” for an event.

Where Sizewright fits in

Every concept from AI art direction comes with the headline in three lengths, an optional subline in three lengths and a button in two. In the editor, you can rewrite any line yourself or ask for a shorter, clearer, more direct, warmer or more formal version, and choose whether to apply it. Copy integrity is one of the measured rules in quality control, checked on every banner.