The standard GURPS approach to racial scale relies on a realistic principle: the square-cube law. If a race’s shape is kept the same but its longest dimension is doubled, its other two dimensions must also double; that multiplies its volume, and therefore its weight, by 2×2×2, or the cube of 2. On the other hand, its
体力 is doubled, and its Basic Lift is multiplied by 2×2, or the square of 2 (in proportion to the cross-section of its muscles). Using the Size and Weight Table (p. 13) gives results consistent with the square-cube law. Longest dimension, weight,
体力, and HP all have the same modifier for scale ――the racial
SM.
Examples: An average human being weighs 125 lbs., and has BL of 20 lbs., or 16% of their weight. A tarantula weighs about 2 ounces (0.125 lb.), giving it
SM -6; based on this, it has
体力 1 and HP 1. Its BL is 0.2 lb., or 3.2 ounces, which is 160% of its weight! (To have the proportionate strength of a spider, you need to have the proportionate size of a spider.)
To obtain exact scale values relative to
SM 0 ――especially for races based on animals with known weights ――divide weight in pounds by 125 (or multiply weight in tons by 16) and use this as a weight multiplier. Take its cube root to find the multiplier for
体力, HP, and longest dimension. Figure
SM from longest dimension.
Example: An Indian elephant averages 4.4 tons. Multiplying by 16 gives a weight multiplier of 70.4. Taking the cube root gives a
体力, HP, and length multiplier of 4.13, for
体力 41, HP 41, and length 25’ (
SM +4).