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Specificity Sells: The Core Principle of Conversion Copywriting

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Most marketing copy is vague. “Boost your results.” “A better way to grow.” “The smarter solution.” It sounds professional. It says nothing.

Conversion copywriting is the discipline of writing words that get people to act — to click, sign up, or buy. And the single most important principle behind it has been proven for over a century.

Be specific.

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What is Conversion Copywriting?

Conversion copy has one job: move the reader to act. Not to feel informed, not to be entertained — to click, sign up, or buy.

The metrics are concrete — conversion rates, click-through rates, sign-ups, revenue. If the copy doesn’t move the number, it isn’t working. This makes conversion copywriting closer to sales than to storytelling.

Why Specificity Is the Rule That Matters Most

In 1923, Claude Hopkins wrote the most cited principle in advertising history:

“Platitudes and generalities roll off the human understanding like water from a duck. They leave no impression whatever. Actual figures are not generally discounted. Specific facts, when stated, have their full weight and effect.”

— Claude Hopkins, Scientific Advertising (1923)

A century later, the principle holds. Specific, concrete language consistently outperforms vague alternatives — in headlines, ads, landing pages, emails, and CTAs.

The evidence

Tom Goodwin at Contentere recently shared A/B test results that show this pattern clearly:

The specific version won every time. Not because it was cleverer — because it was concrete. The reader could picture it.

Hopkins documented the same pattern a hundred years earlier:

The mechanism is simple. Vague claims invite scepticism. Specific claims carry their own proof. When you say “33% more light,” the reader accepts it. When you say “brighter,” they think, says who?

Why Most Copy Stays Vague

If specificity works so well, why is most marketing copy still generic?

It takes more work. Finding specific language means researching the product, talking to customers, and digging into details most marketers skip — because they assume the reader already understands the product. Vague copy is easier to write and easier to get approved.

It feels risky. Specific claims can be challenged. “33% more light” invites scrutiny. “Brighter” does not. Teams default to safe, unmeasurable language because no one can prove it wrong — but no one is persuaded by it either.

The result is what some call the sea of sameness — an ocean of interchangeable messaging where every product is “the smarter way to [verb]” and no brand says anything memorable.

How to Find Specific Language

Specificity doesn’t come from brainstorming sessions. It comes from research. Here are four practical methods:

1. Customer interviews

Thirty minutes with a real customer will give you language no copywriter can invent. Listen for the exact words they use to describe their problem, the moment they decided to look for a solution, and what they’d tell a friend.

The phrases that sound most natural in conversation are usually the ones that convert best in copy.

2. The read-aloud test

Read your copy out loud. If it sounds like something a human would say to another human, keep it. If it sounds like a brochure, rewrite it.

Nobody says “we empower teams to optimise their workflows” at a dinner table. They say “it saves us about three hours a week on reporting.”

3. Job-to-be-done framing

Instead of describing what your product does, describe the specific situation where someone needs it. Instead of “automated reporting tool,” write for the situation: “You’re pulling numbers at 5pm on Friday and your dashboard won’t load.” The jobs-to-be-done framing forces specific language because it starts with a real moment, not a feature list.

4. Before-and-after specificity

Take any line of copy and replace every vague word with something concrete:

VagueSpecific
Healthier snackHitting 110g protein daily
Reminds me of FranceReminds me of the bakery on Rue Cler
Better lighting33% more lumens than the leading brand
Save time on reportingCut your Friday reporting from 3 hours to 20 minutes

The specific version is harder to write. It’s also harder to ignore.

Conversion Copywriting Frameworks

Frameworks like PAS, AIDA, and FAB give your copy structure (see our guide to writing frameworks for marketers for a full breakdown with examples). But the framework you choose matters far less than the specificity of the language you put inside it. A PAS email with vague pain points will lose to a PAS email with concrete, researched details every time.

Putting It Into Practice

Conversion copywriting is not a creative exercise. It is research turned into sentences. Find the specific detail your customer already uses to describe their problem, put it in front of them, and measure what happens.

Start with one piece of copy today. Find the vaguest line. Replace it with something specific. Then test it.

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