2 April 2024

The Technology Readiness Level (TRL) scale is used to assess the technological maturity of an innovation or technology before its operational implementation. This tool is commonly used in the field of research and development (R&D) to provide a common understanding of a technology’s degree of readiness.

A NASA initiative

NASA (National Aeronautics and Space Administration) developed the TRL scale in the 1970s. Originally, this tool had 7 levels of maturity and was used to manage the technological risks of NASA programmes. It was not until 1995, however, that a final, global version of the scale was published, comprising 9 different maturity levels altogether.

Definition of maturity levels

The TRL scale is made up of nine levels, numbered from 1 to 9, representing different stages of technological development. Each TRL is associated with specific criteria that describe the characteristics and performance of the technology at that stage of development.

What does a TRL mean?

Evaluating a technology’s TRL enables us to understand where it is in its development cycle and to identify the remaining stages required to reach maturity and commercialization.

The scale is used by researchers, engineers, companies and organizations to assess the TRL.

The 9 TRLs


  • TRL 1 – Fundamental research
    This is the initial stage of research in which the scientific principles are investigated and understood.
  • TRL 2 – Applied research
    Scientific principles are applied
    to develop technological concepts and prototypes.
  • TRL 3 – Experimental proof of concept
    Experiments are carried out 
    to demonstrate the feasibility of the technology and validate the basic principles.

Research, development and demonstration

  • TRL 4 – Laboratory verification
    The technology is tested in the laboratory to evaluate its performance and functionality.
  • TRL 5 – Simulated environment validation
    The technology is tested in simulated conditions approximating the actual environment it is to be used in.
  • TRL 6 – Validation in an operational environment
    The technology is tested in an operational environment to assess its performance in real-life conditions. This crucial stage calls for the demonstration of an actual system’s prototype.


  • TRL 7 – Initial operational deployment
    The technology is put to limited operational use and evaluated (at prototype scale) under real-life conditions.
  • TRL 8 – Qualified system with proof of functionality in the operational environment
    The technology is used on a large scale in its final form. Full integration and validation completed.
  • TRL 9 – Market-ready technology
    The technology in its final form is fully developed, validated and ready to be marketed and deployed on a large scale.

The TRL scale and public funding

Horizon Europe

In 2014, the TRL scale was incorporated in projects funded by the European Union (EU) as part of the Horizon 2020 framework programme.

The Horizon Europe programme then adopted the TRL scale as an indicator to improve the positioning of projects applied for in the programme. This unified scale enables applicants and evaluators to meet the expectations of the European Commission (EC).

This makes the TRL scale a key tool in the Horizon Europe 2021-2027 framework conditions for participation. To be eligible for funding, projects need to meet the following requirements:

ActivityFunding rateTRL
RIA Research & Innovation Actions100 % + 25 %4 – 6
IA Innovation Actions70 % + 25 %6 – 8
CSA Coordination & Support Actions100 % + 25

A higher TRL in a call text thus clearly indicates that the EC is looking for a more applicative solution within the project, while a lower TRL indicates that a more fundamental research project is expected.

The TRL is also used to indicate the ‘entry point‘, i.e. the maturity level of a given technology, product or process at the start of the project. In this case, the respective TRL serves as the ‘lower limit’.

Innovation grants and subsidies

In the application procedure for subsidies and innovation, funding agencies use the TRL scale to assess the eligibility of different innovative projects.

Funding of innovation projects

Funding of investment projects


The TRL scale is also used to assess the eligibility of projects for tax credits, such as the Research Tax Credit (CIR) and Innovation Tax Credit (CII).

Projects in the early stages of development are eligible for CIR, while projects further up the TRL scale are eligible for CII.

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