I don't own this toy, but it does have a "real size" feature on the product page. If you click here
and choose '1:1 View Actual Product size' it'll bring up an image of the toy. What you do, then, is hold up a credit card or dollar bill to the examples on the site until it's sized properly. After it's sized properly, so that the CC/Dollar is identically sized to the examples you can hold up other toys that you already own, or other objects to gauge the size accurately.