It is best to get three or more quotes from roofing contractors before you deciding.
The rates will vary widely based on the contractors experience, his overheads, whether he is licensed, bonded and insured and whether his workers are covered.
Some contractors might use workers who are not covered under insurance or licenses and hence charge you less.
It is up to you whether you choose to work with those type of contractors.
Do, make sure that you are not liable for any work related accidents at you site.
To make accurate estimates, the roofing shingles calculators needs certain details like the area of the roof.
This can be measured in a couple of ways – one is the sheet count method.
The other is measuring the floor area and then multiplying it with the sloping constant based on the pitch of your roof.
Second, if your roof is low, medium or steep pitched.
The steeper the roof, higher is the cost of labor for roofing.
Third the how simple or complex is your roof?
Large number of dips and highs, vents and projections, windows and skylight on the roof qualify it as a complex one.
Roofs with one or two valleys and a chimney or two qualify as simple roofs.
The more features on the roof there are, the more effort a roofing contractor has to put into it to seal all the gaps and make the roof water tight.