Technology readiness levels (TRL 1–9) explained with examples

What each technology readiness level from TRL 1 to 9 means, with hardware, software and biotech examples, and the TRL that EIC funding calls expect.

Technology readiness levels (TRLs) are a nine-step scale for rating how mature a technology is, from TRL 1, basic principles observed, to TRL 9, an actual system proven in an operational environment. Roughly, TRL 1–3 covers research up to a first proof of concept, TRL 4–6 covers validation and demonstration in the lab and in a relevant environment, and TRL 7–9 takes the full system from a prototype in the real operating setting to a qualified product in normal use. NASA built the scale for its space programmes, and the European Commission now uses it in Horizon Europe and the European Innovation Council (EIC) to decide which funding fits a project. If you are applying for EU money, your TRL is often an eligibility test, not just a label.

Where the TRL scale comes from

A NASA technical paper on TRL assessment credits NASA researcher Stan Sadin with conceiving the method in 1974. It began with seven levels and grew to nine in the 1990s; John Mankins of NASA Headquarters wrote expanded definitions in a 1995 white paper. The US Department of Defense, the US Department of Energy and the European Space Agency later adopted it, and ISO 16290:2013 standardised TRL definitions for space systems.

The European Commission brought TRLs into Horizon 2020 work programmes from 2014 and kept them in Horizon Europe. As of October 2026, the official wording sits in the eligibility section of the Horizon Europe Work Programme 2026–2027 General Annexes, and the EIC Work Programme 2026 uses the same nine definitions. They apply wherever a call requires a TRL, unless the call text says otherwise.

The nine levels in the EU wording

1. TRL 1 – Basic principles observed
2. TRL 2 – Technology concept formulated
3. TRL 3 – Experimental proof of concept
4. TRL 4 – Technology validated in a lab
5. TRL 5 – Technology validated in a relevant environment (industrially relevant environment in the case of key enabling technologies)
6. TRL 6 – Technology demonstrated in a relevant environment (industrially relevant environment in the case of key enabling technologies)
7. TRL 7 – System prototype demonstration in an operational environment
8. TRL 8 – System complete and qualified
9. TRL 9 – Actual system proven in an operational environment (competitive manufacturing in the case of key enabling technologies, or in space)

Two terms carry most of the meaning. A relevant environment reproduces the conditions that matter for the intended use, such as a test rig, simulator or pilot line. An operational environment is the real setting: a customer's plant, a live network, a vehicle on the road.

Each level in plain English, with examples

The examples follow three tracks: a new battery cell, software, and a drug candidate. The drug track follows the pharma mapping on the Commission's EURAXESS portal; the hardware and software readings are illustrations, since the EU definitions are generic.

TRL 1: basic principles observed

An effect that might be useful has been observed and reported; nothing has been built. Hardware: a study reports that a new electrode material stores more charge. Software: a mathematical result suggests a faster method for a class of problems. Biotech: published findings link a biological target to a disease. Evidence: papers and literature reviews.

TRL 2: technology concept formulated

A practical application has been proposed, based on analysis rather than experiments. Hardware: a cell design with modelled performance. Software: an algorithm and architecture on paper. Biotech: a hypothesis and candidate molecules. Evidence: concept studies and models.

TRL 3: experimental proof of concept

The first experiments show that the critical function works. Hardware: small lab cells confirm the material behaves as predicted. Software: a prototype algorithm beats a baseline on a benchmark dataset. Biotech: limited in vitro and in vivo models give initial proof of concept. Evidence: reproducible lab data.

TRL 4: technology validated in a lab

Basic components work together in the lab, often as a crude breadboard. Hardware: hand-built cells cycled on lab equipment against target specs. Software: core modules integrated and run on test data. Biotech: first preclinical animal studies of safety and toxicity. Evidence: lab test reports against defined targets.

TRL 5: technology validated in a relevant environment

The technology, with realistic supporting elements, is tested under conditions that mimic the real application. Hardware: near-production cells tested across the temperatures and load profiles of the target vehicle. Software: the system runs on realistic data volumes and interfaces in a staging setup that mirrors a customer's systems. Biotech: pilot lots of the drug candidate, safety and toxicity studies under good laboratory practice (GLP), and Phase 1 trial protocols. Evidence: test reports that document the conditions and why they are representative.

TRL 6: technology demonstrated in a relevant environment

The step from 5 to 6 is from validating the technology to demonstrating a representative prototype of the whole system; NASA's TRL page describes a fully functional prototype or representational model. Hardware: a prototype pack with its management electronics on a bench that simulates real driving cycles. Software: a feature-complete prototype run end to end on real data in a customer-like test environment. Biotech: Phase 1 trials testing safety in a small group of people. Evidence: a demonstration report on system-level performance.

TRL 7: system prototype demonstration in an operational environment

The prototype leaves the test bench and runs in the real setting. Hardware: packs fitted to a few vehicles on public roads. Software: a pilot at a customer site on live data and real workloads. Biotech: Phase 2 trials showing initial efficacy. Evidence: pilot reports, including problems found and fixed.

TRL 8: system complete and qualified

The final version has passed the tests and approvals needed to deploy or sell it. Hardware: safety and certification testing, plus pre-series manufacturing. Software: a release candidate passes acceptance, security and compliance testing. Biotech: Phase 3 trials and a marketing authorisation application to regulators such as the European Medicines Agency. Evidence: qualification and certification records.

TRL 9: actual system proven in an operational environment

The product works in normal use; in NASA's terms, it is flight proven after a successful mission. Hardware: cells in series production. Software: routine use by paying customers. Biotech: the medicine is on the market, with Phase 4 safety monitoring.

Which TRL EU funding expects

As of October 2026, the EIC Work Programme 2026 sets these TRL windows:

• EIC Pathfinder: early-stage research at TRL 1 to 4. Challenge projects typically start around TRL 2 and aim for proof of concept or lab validation (TRL 3 or 4). Grants of up to €4 million, or more if duly justified.
• EIC Transition: proposals must build on results from an eligible earlier project, such as an EIC Pathfinder or ERC Proof of Concept grant, that have completed TRL 3 and are not beyond TRL 4. Projects should reach TRL 5 to 6 by the end. Grants are up to €2.5 million.
• EIC Accelerator: applicants must have completed all aspects of TRL 5; the 2026 Accelerator Challenge on fusion power plants is an exception and accepts TRL 4 to 6. The grant component, below €2.5 million, covers innovation activities from TRL 6 to TRL 8, and an investment component of €1 million to €10 million supports scale-up.

Other Horizon Europe calls state the expected TRL in each topic. The General Annexes describe research and innovation actions (RIA) as work up to a small-scale prototype in a lab or simulated environment, and innovation actions (IA) as prototyping, piloting and large-scale product validation. For the Accelerator process, see our guide on how to apply to the EIC Accelerator.

How to self-assess your TRL

Applicants declare their own TRL, and EURAXESS notes the scale is self-declared and differs by sector. Evaluators test the claim: at the EIC Accelerator's full-proposal stage, a technology expert checks it against third-party information and in a meeting with your team. Mistakes to avoid:

• Rating the best part, not the weakest. For EIC Transition, a proposal combining several technologies is assessed at the lowest TRL of its core components or subsystems.
• Counting a level that is only partly done. The EIC asks whether you have completed all aspects of TRL 5, not most of them.
• Treating a test rig as the field. A lab demo is not TRL 7, which needs the operational environment.
• Confusing maturity with traction. Early sales do not by themselves prove TRL 8 or 9; the EIC weighs market and business readiness separately.
• Aiming too high. Overstating your TRL can make you ineligible: EIC Transition, for example, excludes results beyond TRL 4.

The Horizon Europe NCP Portal hosts a TRL self-assessment tool, which the EIC Work Programme 2026 points applicants to.

What the scale does not tell you

TRL measures technical maturity only; it says nothing about demand, pricing or a team's ability to sell. The Commission notes important differences between technological fields and treats TRLs as guidance that does not rule out support for non-technological innovation. A battery maker in climate tech and a company in AI will back the same level with very different evidence, so startups should spell out what each claimed level means for their product.

Frequently asked questions

What is the difference between TRL 5 and TRL 6?

At TRL 5 the technology has been validated in a relevant environment that mimics real conditions. At TRL 6 a representative prototype of the whole system has been demonstrated in that kind of environment.

What TRL do you need for the EIC Accelerator?

As of October 2026, applicants must have completed all aspects of TRL 5, meaning validation in a relevant environment; the 2026 fusion challenge is the exception, accepting TRL 4 to 6. The Accelerator grant then funds work from TRL 6 to TRL 8.

Who invented technology readiness levels?

The method was conceived at NASA by researcher Stan Sadin in 1974. NASA's John Mankins wrote expanded definitions for the nine-level scale in a 1995 white paper.

Can software have a TRL?

Yes. The EU definitions are generic, though the Commission notes they play out differently across fields. For software, a common reading is a realistic staging setup at TRL 5–6, a live pilot with a customer at TRL 7 and routine production use at TRL 9.

What does TRL 9 mean?

TRL 9 means the actual system has been proven in its operational environment, so it works in normal use. For key enabling technologies, the EU definition adds competitive manufacturing.