In the satellite photo the cloud cover stretches from the southern tip of New Guinea to the northern tip of New Caledonia.That's 1130-ish miles. Open Google Earth, select the Ruler and, starting at the southern tip of Florida, draw a line North for 1130 miles.
OR
Start at London and draw a line 1820km across Europe and down the length of Italy.
That's the area the cloud from Yasi covers.The actual cyclonic area is 500km across.