TRL Levels Explained: Technology Readiness Levels 1 to 9
TRL Levels, or Technology Readiness Levels, are used to measure how mature a technology is. They help grant assessors, investors and innovation teams understand whether a project is still at scientific concept stage, early proof of concept, prototype validation, or market-ready deployment.
The TRL Levels scale runs from TRL 1, where basic principles have been observed, to TRL 9, where the technology has been proven in real use. The scale is widely used in European innovation funding and is explained in the official EURAXESS guide to Technology Readiness Levels.
For companies applying for innovation grants, TRL Levels matter because they define the starting point, technical risk, project scope and expected development endpoint. At Novigo Grants, we help SMEs define their current TRL, evidence their technology maturity, and structure credible TRL progression for Innovate UK, Horizon Europe and EIC Accelerator applications.
Why TRLs matter in grant applications
TRLs help define the starting point and end point of a project. This is essential in innovation funding because assessors need to understand what public money will actually change.
A strong application does not simply say, “we are at TRL 6.” It explains why. It should describe what has been built, where it has been tested, what performance has been observed, and why the test environment is representative of real use. EURAXESS also notes that TRLs are self-declared and can differ between sectors, which means applicants must justify the level rather than assume the assessor will accept it.
This point is often missed. A TRL claim without evidence is weak. A TRL claim supported by test data, prototype descriptions, operating conditions, user feedback or validation reports is materially stronger.
TRL Levels 1 to3: from principle to proof of concept
TRL 1 is the beginning of the innovation pathway. At this stage, scientific research has identified basic properties or principles. In hardware and systems, EURAXESS describes this as scientific research translated into applied activity, often through paper studies of basic properties.
TRL 2 moves from principle to possible application. The concept is still speculative. There may be analytical studies, but there is no working proof of concept. In practical terms, this is where a research team can describe what might be possible, but cannot yet show that the technology works.
TRL 3 is the first real proof of concept. Analytical and laboratory studies are used to validate earlier assumptions. The important word is “validate”. At TRL 3, the project should move beyond theory and show that the core technical principle can work under controlled conditions. This does not mean the product works. It means the underlying mechanism has been demonstrated.
TRL Levels 4 to 5: from laboratory concept to integrated prototype
TRL 4 is where basic technology components are integrated. EURAXESS describes this as a low-fidelity system, sometimes an “ugly prototype” or “pre-prototype”, assembled in a laboratory environment.
“Low fidelity” means the prototype does not yet look or behave like the final product. It may use ad hoc hardware, manual workarounds, temporary software or simplified operating conditions. This is normal. The purpose is to show that key components can work together.
TRL 5 is a stronger laboratory-stage prototype. Components are integrated with more realistic supporting elements and tested in a simulated environment. EURAXESS refers to high fidelity being achieved in the laboratory.
The difference between TRL 4 and TRL 5 is important. TRL 4 asks whether the components can be integrated. TRL 5 asks whether they can perform in a more realistic test configuration. For grant applications, the move from TRL 4 to TRL 5 often requires better test protocols, more representative input data, improved prototype architecture and clearer performance benchmarks.
TRL 6: prototype tested in a relevant environment
TRL 6 is a critical threshold in many innovation funding schemes. EURAXESS defines it as the point where technology is tested in a relevant environment and starts to be considered a representative prototype. This may involve high-fidelity laboratory testing or a simulated operational environment.
A “relevant environment” is not the same as a real market deployment. It means the test conditions are sufficiently close to real operating conditions to provide credible evidence. For a medical technology, this may involve clinically relevant data or controlled clinical workflows. For hardware, it may involve environmental conditions, mechanical loads, interfaces or user processes that resemble final use. For software, it may involve realistic datasets, integration conditions, latency constraints, user roles or security requirements.
TRL 6 is often where applications become credible for major innovation funding. The technology is no longer a research idea, but it is not yet fully proven. That makes it fundable: there is enough evidence to justify investment, but enough remaining technical risk to justify public support.
TRL Levels 7 to 8: from prototype to operational readiness
TRL 7 moves testing into an operational environment. EURAXESS describes this as the first fully approved prototype, with testing moved into environments such as vehicles or machines.
At this stage, the question changes. Earlier TRLs ask whether the technology works. TRL 7 asks whether it works in the intended setting. This may expose problems that laboratory tests cannot reveal: installation constraints, operator behaviour, maintenance issues, environmental variation, integration complexity or reliability under sustained use.
TRL 8 is where the technology is proven in its final form under expected operational conditions. EURAXESS links this stage to intended or pre-production configuration, design specifications, quality and safety conditions, operational suitability and pre-serial manufacturing.
“Pre-serial manufacturing” means the product is not yet in full industrial production, but manufacturing is being tested and refined before scale-up. This stage is especially important for hardware, medical devices, engineered systems and regulated products. It is where technical performance, quality systems, safety requirements and production feasibility must align.
TRL 9: product on the market
TRL 9 is the final stage. EURAXESS describes this as the point where technology is shaped in its actual application, meets production configuration, and operates under real conditions identified during operational testing and evaluation.
This is no longer a prototype. It is a market-ready or market-deployed technology. For grant applications, TRL 9 activity is often outside the funded R&D phase because it relates to commercial deployment rather than development. However, a credible proposal should still explain how the project will move beyond the funded TRL endpoint towards market uptake.
TRLs differ by sector
A key point from EURAXESS is that TRLs can differ across sectors. The pharmaceutical example shows a very different interpretation from hardware and systems. In drug development, EURAXESS maps TRL 1 to reviewed scientific findings, TRL 3 to design proof of concept, TRL 6 to Phase 1 clinical trials, TRL 7 to Phase 2 clinical trials, TRL 8 to new drug registration, and TRL 9 to distribution and marketing.
This matters because applicants should not use TRLs mechanically. A TRL 6 software platform, a TRL 6 medical device, a TRL 6 rail technology and a TRL 6 pharmaceutical product will not have the same evidence base. The principle is consistent, but the evidence differs. Assessors want to see that the applicant understands the sector-specific pathway.
How to use TRL properly in an application
The best applications use TRLs as an evidence framework, not a slogan. They define the current TRL, justify it with evidence, explain the technical work needed to reach the target TRL, and show how each work package contributes to that progression.
A credible TRL statement should include five elements: the current prototype status, the test environment, the evidence generated, the remaining technical uncertainty, and the funded project endpoint. For example, “the technology is at TRL 5” is weak. “The integrated prototype has been tested in a high-fidelity laboratory environment using representative operating conditions, but still requires relevant-environment validation before operational testing” is stronger because it explains the maturity claim.
TRLs also help prevent overclaiming. Many applicants describe a technology as market-ready when the evidence only supports TRL 4 or TRL 5. This damages credibility. A lower TRL is not necessarily a problem if the project is structured correctly. The problem is claiming maturity that has not been demonstrated.
Why TRLs are useful for investors and funders
EURAXESS states that TRLs are useful for indicating the maturity of research results and defining the steps needed to bring them to market. That is their main value. They convert technical development into a staged pathway that funders and investors can understand.
For funders, TRLs clarify whether the proposed work is research, prototyping, validation, innovation or market deployment. For investors, they indicate how much technical risk remains before commercialisation. For applicants, they create discipline. They force the team to define what has been proven, what has not, and what evidence is needed next.
Need help defining your TRL Levels?
A strong grant application must do more than state a TRL Level number. It must prove the technology’s current maturity using test data, prototype evidence, validation results, operating conditions and a credible development plan.
Novigo Grants helps innovation-led SMEs define their TRL Levels, structure technical work packages, and build evidence for Innovate UK, Horizon Europe and EIC Accelerator applications.
Email ggibbons@novigogrants.co.uk or call 07868 748856 to discuss your project.