The risk-reversal mechanism
When a visitor hesitates at the buy button, the question in their head is "what if this doesn't work for me?" A money-back guarantee answers it directly: "you can get out cleanly." This is rarely about the literal money — it's about removing the fear of being stuck with a bad decision.
The longer-is-better paradox
Counterintuitively, longer guarantees usually convert better and have lower refund rates. ConvertKit and others have published cases where a 90-day guarantee outperformed a 14-day guarantee by 20%+. The mechanism: a longer guarantee signals confidence, and customers who don't feel time pressure forget to ask for refunds.
Where to place it
Right under the CTA, in the same visual unit. "Try free for 14 days · Cancel anytime · Full refund within 30 days" answers three objections in one line and converts better than separate trust badges scattered across the page. Score your trust signals for placement issues.