Affiliate disclosure

As an Amazon Associate I earn from qualifying purchases.

RationMath is a member of the Amazon Services LLC Associates Program. Product pages include "Find it on Amazon" links. If you buy something after clicking one, Amazon pays us a commission. It costs you nothing extra. These links are labeled as paid links where they appear.

Links to each brand's own store are not affiliate links. We're applying to brands' own affiliate programs; if any of those links become paid links, they'll be labeled the same way and this page will say so.

What commissions don't change

• Rankings are sorted only by the formulas in our methodology. No brand pays to be listed or to rank higher.
• Every product we track is listed, whether or not it earns us anything.
• Prices shown on this site come from each brand's own store, not from Amazon. Amazon's price may be higher or lower.