Measured as the ratio of energy put into the fuel to energy released from fusion. For example, the Lawrence Livermore labs experiment released 2.5 MJ of energy from an input of 2.1 MJ, which gives an efficiency of 1.19:1.

Source:

## Related questions

Take into account arbitraging to https://manifold.markets/JamesBills/will-scientists-at-the-nif-produce which is 52%...

Significant part:

NIF is currently upgrading its lasers to 2.2 megajoules

Computer simulations suggest that the output energy could potentially range to as high as seven megajoules.

https://zbr.com.mx/sin-categoria-es/new-advances-in-laser-fusion-generate-more-energy/203183/

Lots of overlap with this question: https://manifold.markets/JamesBills/will-scientists-at-the-nif-produce?r=SmFtZXNCdWNoYW5hbg

The numbers in that Guardian article are out of date. The actual yield from the December shot was over 1.53:1. https://www.ft.com/content/4ff76541-ebdc-43ed-bf4e-4faa75fcf2f9