Can you say "guaranteed" in UK ads?
You can only say "guaranteed" in a UK ad if the guarantee is literally true, unconditional, and something you actually deliver — anything else is treated as a misleading absolute claim. The word does specific work that most marketers don't intend: it promises an outcome to every customer, every time.
Why is "guaranteed" so risky?
UK advertising rules require objective claims to be backed by evidence held before the ad runs. "Guaranteed results", "guaranteed returns" and "guaranteed weight loss" promise a universal outcome, which is almost never evidenceable — individual results vary, so a single customer who doesn't get the result makes the ad misleading. Guarantees of financial returns also collide with financial promotion rules, and guarantees of health outcomes with the medical claims rules.
What are the two meanings of "guarantee"?
There's a legitimate use and a dangerous one. A commercial guarantee you control and honour — "30-day money-back guarantee", "2-year warranty" — is fine, because it describes a promise about your service, not an outcome you can't control. An outcome guarantee — "guaranteed to double your sales" — is the trap.
What's the safer wording that still converts?
Replace the outcome promise with an evidenced specific: "92% of users saw results within 30 days (n=1,204)" outperforms "guaranteed results" and survives scrutiny. Or move the guarantee to something you genuinely back: the refund, the timeframe, the support.
FAQ
- Is "money-back guarantee" allowed?
- Yes, provided you honour it on the stated terms — it's a promise about your service, not a claim about results.
- Can I say "guaranteed" with small print removing the guarantee?
- No — qualifications can clarify a claim but can't contradict it. If the small print takes the guarantee away, the headline is misleading.
- What about "guaranteed lowest price"?
- Only if it's verifiably true and you can substantiate it across the relevant market and period.
Clearance flags "guaranteed", "proven" and absolute outcome claims automatically — run your copy through it before it goes live.
Related rules
This article is general information about publicly available UK advertising rules, not legal advice. Rules change — always check the current codes at source or take professional advice before publishing. Clearance is an independent tool and is not affiliated with the ASA or CAP.