How we pick products

Every buying guide on Serum & Jar covers one kind of product and compares five to eight options. This page explains how those options are chosen and what the comparison is based on.

The short version

We read the listings, not the products. Picks are selected and described from what each Amazon listing states. We have not handled, measured or tested these products, and the guides do not claim otherwise.

What goes into a guide

• In stock with a price. A product is only added if Amazon reports it as available with a price at the time the guide is built. Availability is checked again every day.
• The right kind of product. It has to answer the question the guide is about, not merely be related to it.
• Facts from the listing. Sizes, textures, key ingredients and what is in the box are copied from the listing. If a listing leaves out a detail, the table says "not stated".
• Price per ml. Where the size is stated, cards and tables show the size in ml and the price per ml, worked out from the current price and that size. Prices carry the date they were checked.

What the labels mean

Guides suggest a starting point under headings such as "Closest match" or "Lowest cost on paper". These are our reading of the listings, not test results and not customer ratings. The order of picks is an editorial judgment about how well each listing fits the job.

What this method cannot tell you

• How a cream or serum will feel on your skin, or how it will suit you.
• Whether a fragrance, texture or ingredient agrees with your skin. Patch test new products and read the full ingredient list on the box.
• Whether a listing is sold and shipped by the brand or an authorized seller, which matters for freshness and batch dates.

For those questions, read the recent customer reviews on the listing itself before you buy. The "Limits to know" list on each pick names what the listing does not state.

When a product disappears

If Amazon reports a pick as unavailable, its button changes to a search for in-stock alternatives, and the pick is replaced with a comparable product on the next review of the guide. Page addresses never change.

Questions about a pick? Write to hello@serumandjar.com. See also the affiliate disclosure.