SFI (Solar Flux Index) — Higher is better
| 70 | Poor |
| 80 | Good |
| 90 | Better |
| 100+ | Best |
Higher solar flux values generally suggests better propagation on the 10, 12, 15, 17, and 20 meter bands. Solar flux rarely affects the 30, 40, 60, 80, and 160 meter bands.
A Index — Lower is better
| 1 to 60 | Best |
| 7 to 9 | Good |
| 11 or more | Poor |
Lower A-index values generally suggests better propagation on the 10, 12, 15, 17, and 20 meter bands.
K Index — Lower is better
| 0 to 1 | Best |
| 2 | Good |
| 3 to 4 | Poor |
| 5 | Very poor |