How to choose an aircraft for a route

If I have some routes in mind, how can I calculate which aircraft would be most profitable on that route?

you ever try to think about something before asking for advice?

sorry, anyways

In general, long haul routes = larger aircraft, short haul routes = smaller aircraft

But it can depend on the demand. A high demand route like Tokyo - Osaka is quite a short distance, but you should use larger aircraft on it due to its high passenger demand. Another option is using a high packed narrow body, such as an A321 with 230 seats, and having high frequencies of over 10 a day. A route with low demand should be flown with an aircraft that doesn't have too many seats, and doesn't have excessive fuel consumption so you still make a profit.

Same advice as the other poster, but I'll add some more.    Look at the number of daily/weekly passengers.    If there are a number of city pairs that average around 100 pax per day I'll try and get an aircraft that is about that size so I can offer daily service.   If there is a lot of volume, an A320 or 737 can usually make it daily or perhaps 10-14 weekly if it averages more than your A/C can hold.

On Long Hauls.   I tend to avoid 747 and A380s unless I know I can fill them.