Technology readiness level (TRL)

Technology readiness level (TRL) is a nine-step scale that expresses how mature a technology is, from basic principles observed (TRL 1) to an actual system proven in operation (TRL 9). The scale was developed at NASA to manage development programs. Today it is used by the US Department of Defense, by the European Commission in Horizon 2020 and Horizon Europe, and by many national funding programs. For space systems it is standardized in ISO 16290.

Under the definitions used in EU programs, TRL 1 means basic principles observed, TRL 2 a technology concept formulated and TRL 3 an experimental proof of concept. At TRL 4 the technology is validated in the lab, at TRL 5 it is validated in a relevant environment and at TRL 6 it is demonstrated in a relevant environment. TRL 7 is a system prototype demonstrated in an operational environment, TRL 8 a complete and qualified system and TRL 9 an actual system proven in an operational environment. Wording varies slightly between organizations; the meaning of the levels does not.

In product development terms, levels 1 to 3 correspond to research and lab experiments. Levels 4 to 6 cover working models and functional prototypes, tested first in the lab and then under conditions close to real use (temperature, vibration, humidity, load). Levels 7 and 8 bring pilot deployment, qualification testing and, for regulated products, conformity assessment. TRL 9 means the solution has proven itself in routine operation.

TRL rates technical maturity, not readiness for manufacturing or for the market. Manufacturing has its own complementary scales, such as the manufacturing readiness level (MRL) used in US defense programs. A level also always refers to a specific application: a technology proven in one environment may rate lower in a new, more demanding one.

TRL appears mainly in grant and funding applications. Horizon Europe calls and many national programs state which level a project should reach by its end, and evaluators judge whether the planned progress is realistic. Investors and large customers also use the scale to compare technologies or startups at different stages of development.

Inside a development team, TRL helps with planning. It separates what has been verified from what is still a hypothesis, which shows what prototype and which tests come next. The stretch between TRL 4 and TRL 7, where a lab model has to start working under real conditions, takes a lot of time and money and is also the hardest to fund. That is why it is often called the "valley of death".

The most common mistake is overstating the level. A prototype that worked once on the bench is not TRL 6. Keep evidence for every level you claim: a test report, a description of the test conditions and a comparison of the results with the requirements. Define up front what a relevant and an operational environment mean for your product (temperature range, vibration, dust, humidity, number of cycles). Otherwise the level reached cannot be argued on facts.

In a system built from several technologies, the least mature critical element sets the level, and so does the integration itself: combining two proven components creates a new assembly that has to be verified again. A high TRL also does not mean the product can be made at the target cost. Alongside technical maturity, assess the readiness of manufacturing, the supply chain and certification.