Learn/Checks
How to write your brand’s rules down
A brand book says how the brand should feel. A rule says what every ad must do. How to turn one into the other, so anyone can check a set against it.
The short answerWrite each rule as something a person can check with a yes or a no on any size: the logo’s smallest width and its clear space, the fonts and the smallest type size, the colours and the contrast text needs, the parts every size must carry, and where the legal line goes. Give each rule a number, say which sizes it applies to, keep the list where the work happens, and change it in one place when it changes.
- A rule is a check: anyone looking at any size can answer it yes or no.
- “Use the logo with care” is not a rule. “The logo is at least 80 px wide with clear space of its own height” is.
- Contrast is checkable: 4.5:1 for normal text and 3:1 for large text is a widely used measure.1
- Rules that change by placement say so, such as keeping text out of a Story’s bands.3
On this page
Most brands have rules, and most of those rules live in a long document nobody opens during a launch, or in the head of one person who approves everything. Both fail at volume. A set of 30 sizes cannot be checked against a feeling, and it cannot wait for one person’s eyes. Rules written as checks can be applied by anyone, on every size, in minutes.
- The brand book, if there is one, and a few approved ads.
- The notes approvers have given in the past: they are the rules nobody wrote down.
- Whoever approves legal copy, for the rules about the small print.
Step 1Write each rule as a yes-or-no check
Go through the brand book and the approvers’ past notes, and rewrite every rule until someone who has never seen the brand could check it. If two people could look at the same ad and disagree about whether the rule was kept, the rule is not finished.
| As it is usually written | As a check |
|---|---|
| Give the logo room to breathe | Clear space around the logo of at least its own height |
| Keep the logo prominent | The logo is at least 80 px wide on every size |
| Text must be legible | Text contrast of at least 4.5:1; large text at least 3:1 |
| Always show the offer | Every size carries the price and the legal line |
| Stay on palette | Only these five colour values, written as codes |
Example. Vague rules rewritten as checks. The values are examples; use your brand’s own.
Step 2Write the logo rules
The logo is the rule broken most often on small sizes, because it is the first thing someone shrinks to make room. Write down its smallest size, its clear space, which version goes on which background, and what may never be done to it.
Write clear space as a share of the logo rather than in pixels, so the same rule works on a small banner and on a full-height Story. A rule in fixed pixels is right at one size and wrong at every other.
Step 3Write the type and colour rules
Name the fonts and their weights, the smallest size each one may be used at, and the colour values the brand uses, as codes. Then add the rule that makes the colours safe for text: a contrast ratio between text and its background. A widely used measure is WCAG’s: at least 4.5:1 for normal text and 3:1 for large text, meaning 18 point or 14 point bold; text in a logo has no requirement.1
| Rule | How to write it | How to check it |
|---|---|---|
| Fonts | Name, weight, and where each is used | Look at the file’s fonts, not the screen |
| Smallest type | In pixels at each size, or as a share of the height | Measure the smallest line on the smallest size |
| Colours | Exact codes for every colour allowed | Sample the colours in the export |
| Contrast for text1 | 4.5:1, or 3:1 for large text | A contrast checker on the text and what is behind it |
The contrast values from WCAG 2.2, Success Criterion 1.4.3.1
Step 4Write which parts every size must carry
List the parts an ad must have on every size (usually the logo, the product, the price and the legal line) and the parts that may be dropped on the smallest ones. Then write the legal line’s rule separately, with whoever approves legal copy: where it sits, its smallest size, and whether it may ever move to the landing page.
The FTC’s guidance on digital ads asks for a needed disclosure to sit close to the claim it qualifies, and to be built into a space-constrained ad whenever possible.2 Writing that down as a rule (“the legal line is on every size, directly under the price”) turns a legal principle into a check anyone can do.
Step 5Keep the rules where the work happens
Number every rule, say which sizes or placements it applies to, and keep the list where the people making and checking ads will see it while they work. Some rules depend on the placement: on Instagram Stories, Meta asks you to keep 14% of the top, 35% of the bottom and 6% of each side free of text and logos, which is a rule for tall sizes only.3
| No. | Rule | Applies to |
|---|---|---|
| 1 | Logo at least 80 px wide, clear space of its own height | Every size |
| 2 | Price and legal line on every size, legal line under the price | Every size |
| 3 | Text contrast at least 4.5:1, large text 3:1 | Every size |
| 4 | No text or logo in the top 14%, bottom 35% or 6% sides | 9:16 sizes |
Example. Part of a rule list. Numbers make notes short: “breaks rule 2 on the 320×50”.
When a rule changes, change it in the list, with the date, and tell the people who use it. A rule that changed in someone’s head but not on the list is the source of most arguments at approval.
Common mistakes
- Writing feelings instead of checks.“Premium” and “clean” cannot be checked on a 320×50.
- Writing sizes in fixed pixels for every size.The rule is right on one size and wrong on the rest.
- Leaving the legal line to the end.It is the rule that decides how much room every other part has.
- Keeping the rules in a document nobody opens during a launch.Rules nobody sees are not applied.
Keep your brand’s rules in eonik. It checks every page against them, pins what is missing where it is missing, and puts it back in one click.
See checks →Questions
How many rules should a brand have?
As few as catch the mistakes that actually happen. Start with the notes your approvers give most often: each repeated note is a rule nobody wrote down. Ten good checks beat a hundred-page brand book that nobody opens during a launch.
Where do the contrast numbers come from?
From the Web Content Accessibility Guidelines, which ask for a contrast ratio of at least 4.5:1 for normal text and 3:1 for large text, and set no requirement for text that is part of a logo.1 They are a widely used measure of whether text can be read.
Should an agency write the rules or the brand?
The brand owns them and the agency applies them. When an agency writes them down from a brand’s notes, the brand should approve the list, so both sides check against the same thing.
Sources
- Success Criterion 1.4.3, Contrast (Minimum), W3C, Web Content Accessibility Guidelines 2.2. 4.5:1 for text, 3:1 for large text, and logos exempt.Checked 26 Oct 2026
- .com Disclosures: How to Make Effective Disclosures in Digital Advertising, US Federal Trade Commission, March 2013. Disclosures close to the claim, on every device the ad runs on, including space-constrained ads.Checked 26 Oct 2026
- Image ad specs on Instagram Stories, Meta Ads Guide. 9:16, 1440×2560, and the 14% / 35% / 6% safe zone.Checked 25 Oct 2026