Child or grownup? Roll 1d6:
|1||Baby; age is 1d6-2 (-1 is under 3 months); 1-11 are male on 1d20|
|2||Kid; age is 4+1d10; 1-10 are male on 1d20|
|3-6||Grownup; roll another 1d6 (see below)|
Most of the time, again, we can skip this step and go on to the next one, which is how old a grownup NPC is.
|1||Adolescent; age is 14+1d6; 1-9 are male on 1d20|
|2||Young adult; age is 20+1d8; 1-9 are male on 1d20|
|3||Thirtysomething; age is 28+1d8; 1-9 are male on 1d20|
|4||Middle age; age is 36+1d10; 1-9 are male on 1d20|
|5||Old; age is 46+1d10; 1-9 are male on 1d20|
|6||Ancient; age is 56+1d30 (you can make this exploding on a 30 to get legendary ages); 1-8 are male on 1d20|
Based on Lichfield, England, 1695. I did some tweaking to make things smoother, and to handle the odd spike of girls born right before this census. But I wanted something where I could roll a d6 and get a general idea of an NPC age, and this is it. I don't care much about the exact age until I've fleshed out the NPC a bit.