The TRL scale was developed by NASA in the 1970s and formalized in 1995. The European Commission adopted it for Horizon 2020 in 2014; it continues in Horizon Europe. NASA and the EU use slightly different wording for the same nine levels as you can see below:
The nine levels
Three bands frame the journey:
- Discovery (TRL 1–3), where NCN-type basic research grants operate;
- Development (TRL 4–6), the valley of death where FNP and NCBR instruments bridge the gap;
- and Deployment (TRL 7–9), where PARP, VC and regulatory approval become the relevant actors.
| TRL | Band | NASA definition | Horizon Europe wording | What it means in practice |
| 1 | Discovery | Basic principles observed and reported | Basic principles observed | An idea or hypothesis. No experimental data yet. |
| 2 | Technology concept and/or application formulated | Technology concept formulated | A concept exists on paper. Potential application identified. | |
| 3 | Analytical and experimental proof of concept | Experimental proof of concept | Lab experiments confirm the basic principle works. | |
| 4 | Development | Component validation in laboratory environment | Technology validated in lab | A working component, tested under controlled conditions. |
| 5 | Component validation in relevant environment | Technology validated in relevant environment | Tested with real-world materials or conditions. | |
| 6 | System/subsystem model demonstrated in relevant environment | Technology demonstrated in relevant environment | A prototype demonstrated. This is the PoC threshold for most funders. | |
| 7 | Deployment | System prototype demonstrated in operational environment | System prototype demonstrated in operational environment | Tested in real conditions, not a lab. Investor conversations become realistic. |
| 8 | System complete and qualified | System complete and qualified | Product works as intended. Regulatory approvals typically required here. | |
| 9 | Actual system proven in operational environment | Actual system proven in operational environment | Market-ready. Product or system in commercial use. |
Note: the EU wording for TRL 5 adds “industrially relevant environment in the case of key enabling technologies.” The NASA and EU scales are aligned but not identical, always use the wording of the program you are applying to.
TRL as a decision tool, not a label
Two projects at TRL 4 can have entirely different risk profiles depending on sector, regulatory pathway and scientific maturity. Overstating TRL in a grant application does not accelerate the project, it mismatches you with funders whose instruments are not designed for your stage and creates reporting problems later. Understating it means missing instruments you could already access.
TRL answers one question: does the technology work? In most deep tech sectors, that is necessary but not sufficient. The frameworks below address the dimensions TRL does not.
Beyond TRL: readiness frameworks by sector
These frameworks are not alternatives to TRL; they run in parallel. A project can be at TRL 7 and MRL 3 simultaneously: technically proven but not yet manufacturable at scale. Knowing which framework applies to your sector shapes the due diligence conversation with any investor or partner.
| Framework | Full name | Key question it answers | Primary sector | Status |
| TRL | Technology Readiness Level | Does the technology work at the required level of maturity? | All sectors | Horizon Europe mandatory |
| MRL | Manufacturing Readiness Level | Can it be manufactured repeatedly, at cost, by others? | Hardware, medtech, aerospace, defense | DoD policy (MRL Deskbook 2025); 1–10 scale |
| BRL | Biomanufacturing Readiness Level | Is the bioprocess technically, quality- and operationally ready to scale? | Biopharma, biotech, cell & gene therapy | Lopes et al. 2022 (Biotechnology & Bioengineering); 3 parallel axes |
| ARL | Adoption Readiness Level | Is the external environment, customers, regulators, insurers ready to receive it? | Energy, climate tech, grid technology | US DOE official framework; 17 adoption risk dimensions |
| CRL | Commercial Readiness Level | Is the commercial ecosystem, market, finance, value chain ready? | Deep tech generally | University of Sydney (Abbas & Nomvar); widely cited, not a government standard |
| SRL | Societal Readiness Level | Have societal needs and concerns been addressed so the technology will actually be adopted? | Health systems, climate adaptation, digital inclusion | Horizon Europe Cluster 5 pilot, 2025; live requirement in some calls |
| IRL | Integration Readiness Level | How well do two or more components work when combined into a system? | Autonomous systems, space, complex robotics, AI/hardware | Academic origin (Sauser et al. 2006); used by contractors, not DoD policy |
| SRL* | Software Readiness Level | Is the software mature enough for operational deployment? | Software, AI, digital platforms | No agreed standard; Horizon Europe advises adapting TRL wording for software projects |
The key principle
TRL tells you where the project is on the technical axis. Before any conversation with a funder, a CTT, or an investor, know the current TRL, and which of the frameworks above is the next constraint your project will hit.
Sources: NASA TRL Framework (Mankins 1995, 2004); ISO 16290:2013; DoD Manufacturing Readiness Level Deskbook (2025); European Commission, Horizon Europe Work Program 2025; Lopes et al., Biomanufacturing readiness levels, Biotechnology and Bioengineering (2022); US DOE Adoption Readiness Level framework; NCP Flanders, Societal Readiness Level briefing (December 2025); Sauser et al., Integration Readiness Level (2006).
