CM input range of instrumentation amp

[thistle]

Can anyone tell me how to calculate the common-mode input range of an instrumentation amplifier with all op-amps biased from +15V to -15V assuming all op-amps can swing rail to rail.

Thanks.

 

[Proton Soup]

you should look at the specs on the datasheet for your amp

 

[Phrak]

Looks like homework. And we'd need a schematic.