Kp to A-Index Converter
Convert Kp to the equivalent ap/A-index and back, and see the NOAA geomagnetic storm level.
Conversion table
Kp is quasi-logarithmic and ap is linear. The standard conversion is shown below (“o” = exact value, “+” = one third above, “-” = one third below).
| Kp | ap | NOAA scale |
|---|---|---|
| 0o | 0 | - |
| 0+ | 2 | - |
| 1- | 3 | - |
| 1o | 4 | - |
| 1+ | 5 | - |
| 2- | 6 | - |
| 2o | 7 | - |
| 2+ | 9 | - |
| 3- | 12 | - |
| 3o | 15 | - |
| 3+ | 18 | - |
| 4- | 22 | - |
| 4o | 27 | - |
| 4+ | 32 | - |
| 5- | 39 | G1 |
| 5o | 48 | G1 |
| 5+ | 56 | G1 |
| 6- | 67 | G2 |
| 6o | 80 | G2 |
| 6+ | 94 | G2 |
| 7- | 111 | G3 |
| 7o | 132 | G3 |
| 7+ | 154 | G3 |
| 8- | 179 | G4 |
| 8o | 207 | G4 |
| 8+ | 236 | G4 |
| 9- | 300 | G5 |
| 9o | 400 | G5 |
A-index ranges
- 0-7 quiet, 8-15 unsettled, 16-29 active
- 30-49 minor storm, 50-99 major storm, 100+ severe storm
The daily A-index (Ap) is the mean of the eight three-hour ap values. Read the full explanation in the K-index and A-index guide, and check the current value on the live data page.
Data: NOAA Space Weather Prediction Center, NASA SDO. Band conditions are estimates computed by Map For HAM and are indicative only. Methodology and credits · Data feeds · Widgets
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