[tier] * 2^([level]-1) so for example, a silver level 6 mount would be 4 * 2^(6-1) = 128 a brown level 4 pet would be 1 * 2^(4-1) = 8 spirit mount is like level 7 tier 4 side note the tier upgrade system is much more expensive than selling a tier 1 and buying tier 4 if that is what you are trying to...