Fast, accurate DNA, RNA, and protein quantification up to eight samples

The Invitrogen Qubit Flex Fluorometer accurately and quickly measures the concentration of DNA, RNA, or protein in up to eight samples simultaneously. Compared to single-sample microvolume fluorometers, using the Qubit Flex system for multiple samples can reduce your time to data by up to 50%.

The Qubit Flex Fluorometer can also be used to assess RNA integrity and quality. The easy-to-use touchscreen menus make it easy to select and run the assays you need, with results displayed in just a few seconds.


Tip: If you usually quantify only one or two samples at a time, you may find our Qubit 4 Fluorometer to be a more cost-effective solution.


The Qubit Flex Fluorometer shares common features with the Qubit 4 model: It is accurate, specific, sensitive, simple, and fast; it requires as little as 1 µL of sample, even if highly diluted; it offers an onboard Reagent Calculator to help in preparing your working solution; it works with a broad range of Qubit Assays  and applications; and it can measure raw fluorescence in Fluorometer mode.


In addition, the Qubit Flex offers these additional features:

Rapid throughput
Reduce time to data by up to 50%

Additional onboard calculators
Assay Range, Molarity, and Normalization Calculators help you prepare your assays and get to your downstream experiments faster

Digital SmartStart 3D Experience

Self-paced, online educational and reference experience designed to help you get up and running quickly

SAE software for 21 CFR Part 11

As an optional add-on feature, Qubit Flex can support FDA regulation requirements for electronic documentation as outlined in 21 CFR Part 11

Rapid throughput

By quantifying up to eight samples at a time, the Qubit Flex Fluorometer can increase your throughput. If you have more than eight samples, simply load them into additional tube strips and process them sequentially.


The graph shows time to data, including sample prep and measurement, for a given number of samples with the Qubit 4 or Flex Fluorometer as well as a competitor’s instrument. The Qubit Flex Fluorometer can reduce time to data by 50% or more for larger numbers of samples.

The Qubit Flex Fluorometer reduces time to data by up to 50%. A time study comparing the Qubit Flex Fluorometer to the Qubit 4 Fluorometer and another supplier’s fluorometer, using the Qubit 1X dsDNA HS Assay Kit, showed time-to-data reduced by up to 50% with up to 96 samples. 


Tip: For high-throughput quantification, consider using a microplate reader with fluorescence capabilities. The Thermo Scientific Fluoroskan Microplate Fluorometer and Varioskan LUX Multimode Microplate Reader are compatible with Quant-iT assays to quantify the same analytes as Qubit Fluorometers and assays. For a comparison, see our RNA/DNA Quantification page.

Additional onboard calculators

All Qubit Fluorometers feature an onboard Reagent Calculator, which calculates the volume of reagent and buffer to use when preparing your working solution, depending on the number of samples and standards you are testing. It can be used to determine master mix volumes for samples and standards.


The Qubit Flex Fluorometer offers three additional calculators to streamline your workflow. The Assay Range Calculator displays the core sample concentration range for which it is most accurate, based on the sample volume used to quantitate. It will also display the extended low and high concentration ranges based on the quantitation sample volume.

Assay Range Calculator

This calculator helps you choose the Qubit assay that will offer the best accuracy for the amount and concentration of sample available.

Molarity Calculator

Use this calculator to quickly determine the molarity of your sample from its concentration and approximate length in base pairs.

Normalization Calculator

This calculator quickly determines the amount of sample and buffer needed to normalize all samples to the same concentration, mass, or molarity and volume.

To aid your transition to downstream applications, two calculators help you manage assay sample data and perform common unit conversions and dilutions. The Molarity Calculator allows you to determine the molarity of a sample based on nucleic acid length and the measured concentration. For sequencing applications, the Normalization Calculator replaces the spreadsheet often used to normalize samples during library preparation. For each run, it recommends how much sample and buffer to add to reach a desired, normalized mass, concentration, or molarity.

Simple workflow

The user-friendly Qubit Flex Fluorometer delivers results using quick, simple assay procedures. The large, color touch screen allows you to easily navigate through the various options. Calculations and settings are automatically performed by the instrument. In addition, the Qubit Flex integrated Reagent Calculator helps you determine the amount of dye and buffer required to prepare your samples and standards.

Qubit Flex Fluorometer workflow. The Reagent and Assay Range Calculators will help you prepare your assays. Results can be displayed as a graph or a list. (A) Home screen. Select your assay, among other actions. (B) Reagent Calculator. Easily make working solution for all assays that are not 1X. (C) Assay Range Calculator. Determine sample requirements based on required accuracy. (D) Results. See your sample concentrations along a linear standard curve.


The Qubit Flex Fluorometer will save the data for up to 10,000 samples, and you can transfer data to a Thermo Fisher Connect Cloud account via WiFi, or to a computer via a USB drive or Ethernet cable.

Videos and demos

Digital SmartStart 3D Experience gets you started quickly

Every Qubit Flex Fluorometer includes access to a self-paced, online educational and reference experience designed to help you get up and running quickly. The modules include interactive visual demonstrations of how to install, operate, and maintain your instrument.

21 CFR Part 11 Software

Qubit Flex Fluorometers come equipped with an optional add-on Security, Audit, and e-Signature (SAE) software that supports compliance to 21 CFR Part 11.

Service Support

Qubit Flex Fluorometers can come with Field Service Engineer Installation and Operational Qualification (IQOQ) Services. This service will ensure that the Qubit Flex is properly installed and is working within manfucaturer specifications.


In addition to the instrument IQOQ, an add-on Qubit Flex SAE Software OQ can be completed during the same visit. The SAE OQ will ensure that the SAE Software is properly installed and that the connection to the instrument can be made. Further, it will include testing that verifies proper functionality of the SAE Software. The SAE OQ can only be completed in conjunction with an instrument IQOQ.




Physical characteristics

Instrument type

Benchtop fluorometer

Instrument dimensions (W x L x H)

18.6 x 28.2 x 10.3 cm

7.3 x 11.1 x 4.1 in.


1.7 kg; 3.7 lb

Operating power

100–240 VAC, 1.3 A/0.6 A


50/60 Hz

Electrical input

48 VDC, 1.87 A

Installation site

Indoor use only

Operating temperature

10–30° C

Operating humidity

15–80% (non-condensing)

User interface

8-inch color touchscreen

Technical specifications

Dynamic range

5 orders of magnitude

Processing time

≤5 seconds/sample

Light sources

Blue LED (peak ~460–480 nm)

Red LED (peak ~620–640 nm)

Excitation filters

Blue LED (456–484 nm)

Red LED (612–644 nm)

Emission filters

Green (513–563 nm)

Far-red (671–693 nm)


Photodiodes: measurement capability from 320–1,100 nm

Calibration type

2- or 3-point standard

Sample chamber

Accommodates one Qubit Flex Tube Strip

Tube type

Qubit Flex Tube Strip

Warm-up time

<35 seconds

Sample data storage

10,000 samples



8-inch capacitive touchscreen with high-resolution color display

Data ports

3 - USB drive ports (Type A)

LAN port (RJ-45)

Networking capabilities

Connection via the LAN (RJ-45) port using an Ethernet cable or wirelessly using the supplied Wi-Fi adaptor

Power supply

AC adapter with country-specific power cords

USB drive

4 GB

21 CFR Part 11 Software SAE Software

Ordering information

Starter kit comparison guide

Qubit Flex Fluorometer

Qubit Flex Quantitation Starter Kit

Qubit Flex NGS Starter Kit


Qubit Flex Fluorometer

Qubit Flex Fluorometer

Qubit Flex Fluorometer

1 regional power adapter

1 regional power adapter

1 regional power adapter

Microfiber cloth

Microfiber cloth

Microfiber cloth

USB drive

USB drive

USB drive

Digital SmartStart 3D Experience

Digital SmartStart 3D Experience

Digital SmartStart 3D Experience

3-year warranty

3-year warranty

3-year warranty


Qubit Flex Assay Tube Strips (125 strips)

Qubit Flex Assay Tube Strips (125 strips)


Qubit Flex Assay Reservoirs (100 reservoirs)

Qubit Flex Assay Reservoirs (100 reservoirs)


Qubit 1X dsDNA HS (high sensitivity) Assay Kit (100 assays)

Qubit 1X dsDNA HS (high sensitivity) Assay Kit (500 assays)


Qubit dsDNA BR (broad range) Assay Kit (100 assays)



Qubit RNA HS (high sensitivity) Assay Kit (100 assays)



Qubit RNA BR (broad range) Assay Kit (100 assays)



Qubit Protein Assay Kit (100 assays)



Qubit Flex System Verification Assay Kit





For information about assays for the Qubit Flex Fluorometer, see the Assays tab.

For Research Use Only. Not for use in diagnostic procedures.