3.5 ton
1 and half to 2 ton
2.5 ton should do it
If the house is well insulated, a 4 ton unit should work pretty well in about 1800 sq feet. But if the insulation is not good enough, then you need to go with a larger unit.
4 ton depending on construction and location.
1 ton per 500 sq ft. so 5 will do
3 ft = 1 yard so 1250 ft = 1250/3 = 416.66... (recurring) yards.
2.5 ton a/c unit
2.5 ton
No. You at least need a 3.5 to 4 ton.
A 4 ton unit will be adequate usually 1 ton per 400 square ft of living space
A 3 ton is ideal more for a house that's 1200 sq. ft, I would recommend a 2.5 ton