What Is a PCR Tube? A Plain-Language Guide

Last verified: October 6, 2026. A PCR tube is a small, thin-walled plastic tube designed to hold a very small volume of liquid while it is rapidly heated and cooled. The name comes from the polymerase chain reaction (PCR), a widely used method for making many copies of a short stretch of DNA. That method works by cycling a reaction mixture through a repeating series of temperatures, and the tube has to carry heat in and out of the liquid quickly and evenly, stay sealed against evaporation, and not interfere with the chemistry. A tube that does those three things well is a PCR tube, and although it was named for one technique, it is used for many other small-volume, temperature-sensitive reactions as well.

Why does the tube matter at all? Because in a thermal cycler the liquid never touches the instrument. Heat has to pass from a metal block through the plastic wall into a reaction that may be only a few microliters or tens of microliters. Thick walls slow that transfer and make temperature changes sluggish and uneven. Thin walls, a precise fit in the heating block, and a tight cap are what allow a run to behave the way the protocol assumes.

Who Uses PCR Tubes, and Why

PCR tubes appear anywhere nucleic acid work is done at small scale:

• Research laboratories in molecular biology, genetics, microbiology, plant science, and cell biology, for amplifying DNA, checking whether a sequence is present, or preparing material for sequencing.
• Clinical and public-health laboratories, where amplification-based tests detect the genetic material of organisms or particular variants in patient samples.
• Forensic, agricultural, and environmental laboratories, for identifying species, testing food or seed lots, or screening environmental samples.
• Teaching laboratories, where students learn amplification with small, inexpensive consumables.

The same tubes are also used for other small reactions, such as enzymatic digests or ligations run on a heating block, and sometimes for short-term storage of tiny aliquots. For the instrument that normally heats them, see what a thermal cycler is.

Common Formats and Types

Individual tubes

The simplest format is a single small tube, usually with an attached, hinged dome or flat cap. Individual tubes are flexible when only a few reactions are needed, but they are easy to mix up and slower to handle in bulk.

Strip tubes

Strip tubes join several tubes, commonly eight in a row, into one piece, with caps that are either individual or joined in a matching strip. They match the layout of multichannel pipettes and of a plate column, which speeds up setup and reduces handling errors.

PCR plates

For larger runs, a plate with a grid of PCR-sized wells does the same job as dozens of tubes. Plates are sealed with an adhesive film or a heat seal rather than individual caps. They are related to, but not the same as, standard assay plates; see what a microplate is for how multiwell formats are organized.

Cap styles

Domed caps allow a little headspace and are common in many cyclers. Flat caps are preferred for instruments or optical systems that need a flat surface, such as real-time (quantitative) instruments that read fluorescence through the cap. Choosing the wrong cap shape can affect both sealing and optical readings.

Wall thickness and profile

Standard thin-walled tubes suit most conventional cyclers. Some instruments are designed around low-profile tubes or plates that sit differently in the block. The tube has to match the block’s wells closely; a loose fit leaves air gaps that slow heat transfer.

Material and treatments

PCR tubes are usually made from polypropylene, which tolerates repeated heating well and is relatively inert. Many are sold as certified free of contaminating nucleic acids, nucleases, or inhibitors, because even trace contamination can show up as a false result in a technique designed to amplify tiny amounts of DNA. Some are made from low-binding plastic to keep valuable material from sticking to the wall.

How a PCR Tube Differs From Adjacent Equipment

• PCR tube vs. microcentrifuge tube. A general-purpose microcentrifuge tube is thicker-walled, larger, and designed for spinning, mixing, and storage. A PCR tube is thinner for heat transfer and sized to fit a thermal cycler block. Using a microcentrifuge tube in a cycler can lead to poor heat transfer and a poor fit.
• PCR tube vs. conical centrifuge tube. Conical tubes hold many milliliters and are used for larger preparations and for spinning in a centrifuge. PCR tubes work at the opposite end of the scale, with microliter volumes.
• PCR tube vs. PCR plate. Tubes suit small or irregular numbers of reactions; plates suit large, regular batches and automation.
• PCR tube vs. the thermal cycler. The tube is the consumable; the cycler is the instrument. They must be matched, because the cycler’s block and lid are designed around a particular tube or plate format.

Handling and Common Pitfalls

Because PCR can amplify a tiny amount of unwanted DNA as readily as the intended target, the tube is part of a contamination-control system rather than just a container.

• Contamination. Labs often separate reaction setup from the area where products are handled, use filtered pipette tips, and keep tubes capped and in their original bags until needed. Opening a tube after a reaction releases material into the air, which is why post-reaction handling is kept apart from setup.
• Evaporation. A poorly seated cap can let liquid escape during long heating steps, changing the concentration of everything in the tube. Heated lids on cyclers help, but a good cap fit still matters.
• Labeling. The surface of a small tube is limited, and ink can smear or rub off. Many labs label the side of strip tubes or use a plate map rather than writing on caps that will be opened and closed repeatedly.
• Reuse. PCR tubes are normally single-use. Washing and reusing them risks carry-over contamination that is very hard to detect.

Choosing PCR Tubes: The Questions Worth Asking

When a lab selects PCR consumables, a short checklist avoids most problems. Which thermal cycler or real-time instrument will the tubes go into, and does its block take individual tubes, strips, or plates? How many reactions typically run at once, since strips and plates save time for large batches but waste material for small ones? Does the instrument read fluorescence through the cap, requiring a flat optical cap or clear walls? What reaction volume will be used, and does the tube hold it with room for headspace? How sensitive is the application to contamination, and does it justify a certified-clean grade? Will the reaction products be stored in the same tubes, and for how long? Is a low-binding surface needed for precious material? And do the lab’s pipettes and multichannel tools line up with the format chosen? Because tubes are cheap per unit but used by the thousand, making these decisions deliberately once, writing them into a purchasing standard, and revisiting them when instruments change is usually better than choosing case by case.

Practical Notes for Research-Administration and Lab-Management Readers

• Match the tube to the instrument. Before standardizing on a product, confirm that it fits the cyclers actually in use, including any real-time instruments that need specific caps or clear walls.
• Quality grade matters for some work. Basic tubes are fine for teaching and routine checks, while sensitive clinical or low-copy-number work may call for tubes certified for low contamination. Paying for a higher grade only where the work needs it is a reasonable way to control cost.
• Waste and sterility. Used tubes that held biological material follow the institution’s waste rules. The question of which plastics tolerate sterilization is covered in which plastics are autoclavable, though PCR consumables are generally purchased ready to use rather than sterilized in-house.
• Storage space and shelf life. Bagged, pre-sterilized consumables take bench and cabinet space and should be kept sealed and dry. Bulk buying lowers per-unit cost but only helps if the stock gets used.

This page is general information, not clinical or safety training. Follow your institution’s procedures and the manufacturer’s instructions for any specific tube or instrument.

The Short Version

A PCR tube is a thin-walled, tightly sealing plastic tube sized to fit a thermal cycler and carry heat quickly into a tiny reaction. It comes as single tubes, strips, or plates, with domed or flat caps, and in grades that range from basic to certified for very sensitive work. The right choice depends mostly on the instrument, the number of reactions per run, and how sensitive the application is to contamination.

Frequently Asked Questions

What is a PCR tube used for?

Holding small reaction mixtures during the repeated heating and cooling steps of PCR and similar techniques. It is also used for other small-volume reactions that need quick, even temperature changes.

Can I use a regular microcentrifuge tube instead?

Often not as a substitute. Regular tubes have thicker walls and may not fit the heating block snugly, which slows and evens out heat transfer poorly. Protocols and instrument makers generally call for tubes designed for cycling.

What is the difference between PCR strip tubes and a PCR plate?

Strips connect a small number of tubes, commonly eight, for flexible batch sizes. Plates hold many reactions in a grid and suit large runs and automation. Both serve the same purpose with different handling.

Why are some PCR tubes sold as certified clean?

Because the technique amplifies very small amounts of DNA, stray nucleic acid or other contaminants in the plastic can create false results. Certified grades are made and packaged to minimize that risk.

Why do some PCR tubes have flat caps?

Flat caps give a clear, level surface that real-time instruments can read fluorescence through, and they suit some heated-lid designs. Domed caps are common elsewhere.

Can PCR tubes be reused?

They are designed for single use. Reusing them risks carry-over contamination, which is difficult to detect and can invalidate results.