How to Identify Vintage Pyrex (Pattern, Shape & Backstamp)

Found a piece of old Pyrex and want to know exactly what it is? Identifying vintage Pyrex comes down to three things you can read right off the piece: the pattern, the shape, and the backstamp on the bottom. Here’s how to put them together.

1. Identify the pattern

The printed design is usually the fastest way to name a piece. Vintage decorated Pyrex was made on white “opal” glass (opalware) and printed with hundreds of patterns from the mid-1950s onward. Some go by nicknames collectors use more than the official name — Butterprint is widely called “Amish,” and Spring Blossom Green is the “Crazy Daisy.” Match your design against our Pattern Database to find the name, the years it was made, and the pieces in the line.

2. Identify the shape and model number

Every piece has a shape with a three-digit model number stamped on the base. Those numbers are a code for the exact form and size: the 441–444 Cinderella mixing bowls, the 471–475 round casseroles, the 501–503 refrigerator dishes, and so on. Knowing the number tells you what you have and what a complete set looks like. Our Shapes & Model Numbers guide breaks down each one.

3. Read the backstamp

Flip the piece over and look at the markings. Genuine vintage Pyrex carries the Pyrex logo, usually with “Made in USA” and the model number; many pieces also show the size in cups or quarts. The style of that stamp also helps you date the piece — see How to Date Vintage Pyrex. A stamped, slightly worn mark that matches the wear on the rest of the piece is a good sign; a suspiciously crisp mark on an otherwise beat-up piece is worth a second look.

Vintage vs. newer Pyrex

Vintage opalware Pyrex is noticeably heavy, with a smooth white glass body and printed patterns. Later kitchenware sold under the lowercase “pyrex” name (made by World Kitchen and successors) and modern clear bakeware are different products. When in doubt, the combination of an opal-glass body, a known vintage pattern, and a period-correct backstamp is your best confirmation.

Put it together

Name the pattern, read the shape number, and confirm the backstamp — and you’ll know exactly what you have and roughly when it was made. From there, check the pattern’s page for current value, and see our guide to the most valuable Pyrex patterns to find out if you’re holding a grail.

Frequently asked questions

How do I identify a vintage Pyrex pattern?

Match the printed design to a reference like our Pattern Database, then confirm with the shape’s model number and the backstamp on the bottom. Many patterns also have collector nicknames, such as Butterprint being called ‘Amish.’

Where is the model number on Pyrex?

It’s stamped on the bottom of the piece, usually a three-digit number near the Pyrex logo (for example, 441 for a small Cinderella bowl). The number identifies the exact shape and size.

How can I tell if my Pyrex is actually vintage?

Vintage opalware Pyrex is heavy white glass with a printed pattern and a period backstamp that reads ‘Pyrex’ (often with ‘Made in USA’). Newer lowercase ‘pyrex’ and modern clear bakeware are different, later products.