From To S mS uS kS
S 1 1000 1e+06 0.001
mS 0.001 1 1000 1e-06
uS 1e-06 0.001 1 0
kS 1000 1e+06 1e+09 1

Each cell shows the factor to convert 1 unit of the row header into the column header.

Highlighted diagonal cells represent identity conversions (1:1).