Credit for the original calc goes to AguilaR101, the second method was from AntonioFer, and the first scaling image goes to Lina Shields.
Background[]
This recalculation original came from a need to replace the original one due to it using the fireball formula, something exclusive only to nuclear bombs, when this wasn't confirmed to be one. However, near the end of the thread, Lina had actually mentioned a better way to scale, and thus this new calc will use that.
Scaling and Math[]
202 px, 495.5 meters = 760 px, x meters, with x = 1864.3 meters.
1.8643 = ((y^1/3)*0.28), y being yield in kilotons of TNT
(1.8643/0.28)^3 = y, thus y = 295.1 kilotons of TNT, or in other words, High 7-C.
With the second method, that being: 80.3686*10ˆ(-6)* 1864.3ˆ3, which results in 520755 tons, 520.755 kilotons, or in other words, High 7-C.
Downgrade time mates.