Flight Changi Airport departs from Singapore Changi Airport at 20:20 and arrives at Sydney Sydney Airport at 05:55.
The flighttime is about 7h 35m. The distance travelled ("as the bird flies"): 5577 Km. So the average speed is roughly 735 Km.
There is an 2 hour time difference between Singapore and Sydney
The best day to arrive at Singapore is Monday and it would be best to avoid Friday, as prices are on average 58.03% higher than on Monday. (Average prices, based on 402681 datapoints.)
We have a lot more statistics for flights SQ 221 and between Singapore and Sydney.