Good Light indoors has spectral characteristics that vary according to time of day, personal needs, and specific tasks. In the morning and during daytime, the light spectrum should include a reasonable portion of short wavelengths to support the energizing and revitalizing effects of light. In the evening and at night, the amount of short wavelengths should be diminished to support winding down, a good night of sleep and to prevent disruptions of the day-night rhythm. To create a good lighting design, you need to be able to calculate the ‘melanopic EDI’ vertically at eye level. This parameter is introduced in the international standard CIE S 026:2018 CIE System for Metrology of Optical Radiation for ipRGC-Influenced Responses to Light. The CIE has recently launched a free of charge S 026 Toolbox and S 026 User Guide to support the use of this international standard. A short video has been prepared to give some background information on the Toolbox and some brief instructions on how to use it.