Rubber Stopper Size Guide

Your Guide to Rubber Stoppers

In laboratory science, details matter.

Quality reproducible results are only as good as the quality of materials used, the durable laboratory equipment used, and the facilitating scientist. Whether your lab’s processes are qualitative or quantitative, precision and care must be taken at all stages of work for the best outcomes, including selection and handling of all materials and supplies. For example, you might work with biological samples as well as chemicals and reagents in different capacities throughout the laboratory. Sometimes, labs function with several different testing procedures happening simultaneously. A quality control or quality assurance laboratory might test for several different variables in one product, or one variable for several different products. Considering the many booming scientific industries, possibilities for laboratory configurations remain endless.

These larger systems of study and testing must rely on their component parts, the smaller pieces of logistics and operations to support outstanding results and successful outcomes, for the information being sought. These component parts include high-quality laboratory supplies, down to the smallest item: enter the rubber stopper.

Test tubes are slender containers that hold small amounts of liquid or other materials used in testing and storage, for example, blood or tissue samples. Test tubes containing materials or reagents must be properly sealed and stored at all times. High-quality rubber stoppers make this possible. Most commonly made of natural, black rubber, they are pliable and fit tightly when the size is appropriately chosen according to test tube size and opening.

Below you will find a chart with common rubber stopper sizes, the diameter of the top and the diameter of the bottom of each stopper.

Your Guide to Rubber Stoppers

Rubber Stopper #:	Top Diameter:	Bottom Diameter:
000	13 mm	8mm
00	15 mm	10 mm
0	17 mm	13 mm
1	19 mm	14 mm
2	20 mm	16 mm
3	24 mm	18 mm
4	13 mm	8mm
5	27 mm	23 mm
5½	28 mm	24 mm
6	32 mm	26 mm
6½	34 mm	27 mm
7	37 mm	30 mm
7½	39 mm	31 mm
8	41 mm	33 mm
8½	43 mm	36 mm
9	45 mm	37 mm
9½	46 mm	38 mm
10	50 mm	42 mm

The Lab Depot carries several different test tubes from different manufacturers. The United Scientific rubber stoppers we sell will fit all test tubes, based on the sizing chart listed here. They are autoclavable and best for non-aggressive, concentrated solutions.

Considering even the smallest details of your laboratory’s operations yields the highest quality results, even down to the rubber stoppers you use to secure your test tubes. Great science calls for precision. Ensure the quality and reliability of your laboratory’s applications by making sure you are using the best products available.

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