Every EU funding call, including Horizon Europe, the EIC, Eurostars and the Innovation Fund, states a Technology Readiness Level (TRL) range somewhere in its eligibility criteria. Miss it, and your proposal can be rejected before a single evaluator reads the technical content. It's one of the most common, and most avoidable, reasons startups get knocked out of the process early.
What TRL actually measures
TRL is a 9-point scale that describes how mature a technology is: not how good the idea is, not how big the market opportunity is, but specifically how far the technology itself has progressed from a theoretical concept to something proven in real operating conditions. It was originally conceived at NASA in the 1970s and formally defined in 1989 to standardise how engineers talked about hardware readiness, and the European Commission adopted an adapted version for Horizon 2020, carrying it forward into Horizon Europe, where it's formally defined in the Programme's General Annexes (Annex G).
The scale runs from TRL 1 (basic principles observed, no application defined yet) to TRL 9 (the technology has a proven track record in a real commercial or operational setting). Every EU call specifies which TRL range it funds: some fund single-level jumps (e.g. TRL 5 to TRL 6), others fund a wider span.
The nine levels, in three phases
Research (TRL 1–3): Still in the lab, on paper, or in simulation. No working prototype yet.
- TRL 1: Basic principles observed. Fundamental research: literature review, theoretical modelling, no defined application. What this looks like in practice: a peer-reviewed paper describing the underlying mechanism, nothing built yet.
- TRL 2: Technology concept formulated. A specific problem has been identified and the science could plausibly be engineered into a solution. In practice: a patent filing or an engineering sketch of how the concept could actually work.
- TRL 3: Experimental proof of concept. A first lab-scale prototype or numerical model exists; key parameters have been tested and verified. In practice: a working prototype on a lab bench, tested only under controlled conditions.
Development (TRL 4–6): Moving from the lab into conditions that increasingly resemble the real world.
- TRL 4: Validated in lab. A reduced-scale prototype, integrated with sub-systems, produces stable, repeatable results under controlled conditions. In practice: a bench-scale system that's been validated in the lab, but hasn't left it.
- TRL 5: Validated in relevant environment. A larger-scale prototype is tested in conditions that approach real-world use. In practice: a pilot-scale system tested in a simulated operational setting.
- TRL 6: Demonstrated in relevant environment. A full-scale prototype shows robust performance across the range of conditions it will actually face. In practice: a field demonstrator, functional but not yet packaged as a commercial product.
Deployment (TRL 7–9): The technology moves toward, and then into, the market.
- TRL 7: Operational environment demonstration. A full system prototype is tested in real conditions, with end-users giving feedback. In practice: a pre-commercial system tested with real users, in real conditions.
- TRL 8: System complete and qualified. The technology is in its final form, extensively tested and quality-assured, ready for expected use. In practice: a certified, market-ready product already in the hands of its first customers.
- TRL 9: Proven in operational environment. The technology has a documented track record of commercial or operational success; it's actually out there working. In practice: multiple production installations with a proven commercial track record.
Founders sometimes ask why the scale bothers to distinguish TRL 5 from TRL 6, or TRL 8 from TRL 9, the gap looks small on paper. In practice, each of those jumps usually corresponds to a real, expensive milestone: moving from a simulated environment to a real one, or from a working product to one with a certified, repeatable track record. Evaluators read TRL claims as a proxy for how much risk is left in the project, and how much of that risk their money would actually be removing.
Which programme funds which TRL range
- EIC Pathfinder, TRL 1–4: research teams, university spin-offs, radically new technology.
- EIC Transition, TRL 3–6: research spin-offs turning a result into a market-ready product.
- Eurostars, TRL 4–7: R&D-driven SMEs with international partners.
- EIC Accelerator, TRL 6–8: startups and SMEs scaling breakthrough innovation to market.
- EIC STEP Scale-Up, TRL 9+: companies scaling already-proven technology industrially.
(Eurostars doesn't bind eligibility to a fixed TRL band, but projects typically start around TRL 4 and finish around TRL 6–7, per Eureka Network's own Eurostars FAQ.)
As a rule of thumb, Research and Innovation Actions (RIA) under Horizon Europe typically fund TRL 1–4/5, while Innovation Actions (IA) typically fund TRL 4–8. Always check the specific call text: the General Annexes give the default definitions, but individual work programmes can narrow the range further. For the full picture of what each EIC sub-programme actually pays and requires, see EIC Funding Explained.
The mistake almost every applicant makes
Technological readiness isn't the same as commercial readiness. Coordinators regularly overestimate their starting TRL to sound more advanced than they are, or underestimate their target TRL to make the jump look more achievable. A common version of this: a team with a working lab prototype (genuinely TRL 3–4) describes it as "validated" (TRL 5–6) because early informal user feedback felt positive, without a documented test in anything resembling a real operating environment. Evaluators are specifically trained to check for a realistic, evidenced jump between the two, not just a number typed into a form. An unsupported TRL claim is one of the fastest ways to lose credibility with a reviewer before they've even reached the technical merit of the proposal.
Before submitting, it's worth asking:
- Can I point to one concrete document or test result that proves each TRL jump, not just assert it?
- Would an outside expert who has never seen this project agree with my number?
- Does my target TRL actually match the range this specific call funds?
- Am I describing what's proven today, not what I expect to prove by the deadline?
Getting the TRL claim right isn't a box-ticking exercise: it's often the single fastest way to fail (or pass) the eligibility check before the technical evaluation even begins.
Sources
- Horizon Europe Work Programme 2026–2027: General Annexes (Annex G: TRL definitions): European Commission
- EIC Funding Opportunities: European Innovation Council
- Funding & Tenders Portal: Reference Documents: European Commission
- Technology Readiness Levels: NASA (origin of the TRL scale)
- Eurostars Frequently Asked Questions: Eureka Network (confirms Eurostars' typical TRL 4–7 range)