When would I use guarantee instead of guaranty? The dictionary definitions seem pretty much the same. Excepting maybe the noun form of the word.

I have a real world example. A website I'm working on has a 30 day money back guarantee(y?). If you don't like your purchase, within the first 30 days, you can get your money back. Is that a guarantee or a guaranty? If I was going to make a little advertising picture for it, would I say "30 day money back guaranty" or "30 day money back guarantee"?

I am leaning towards guarantee.

1 Answer 1


Short answer: you can't do much harm in using guarantee every time.

Longer answer: the New Oxford American English presents “guaranty” as only slightly different from “guarantee” in meaning, and goes further to list “guarantee” as a variant spelling for “guaranty”. In addition to the information research in Fowler (quoted, for example, here), it seems safe to say that you can use “guarantee” all the time without fear.

  • I mostly agree. If there is any doubt, use "guarantee" as the verbal form of "guaranty" is said to be obsolete. However, for certain legal-related work, they are not the same. I did a site for somebody who was adamant that everything needed to be "guarantee". (Who knew?) So, I'd say use "guarantee" unless you are specifically told by somebody who knows it should be otherwise.
    – fool4jesus
    Commented Mar 3, 2014 at 17:11