Inmmortals total budget is 140m with marketing. I think you are leaving out marketing budget which usually is around the same as production budget.
How I do it is by assuming each studio makes about 55 percent back from theater ticket sales. If it is an older movie I will even go and find out what the DVD sales are. Sometimes you can find the marketing budget and sometimes you cannot. I usually just go with 100 million for movies that cost over 100 million to make, and below that it is hard to decide on. I know a lot of recent movies have been costing 35-65 million to produce. I do not remember which ones I saw that were like that, but it was a good amount. Boxofficemojo has a spot that says total budget, but, I have not been able to find it yet.
Looking at Immortals take overseas I think it will do quite well over there, and it should have a ways to go in America as well. so if 140 million is all it needs to just break even it should not have a problem.
What do you think? Bomb or minor hit? Or big hit for that matter.