CapriKorn mentioned the dimensions of the flag, but not the proportions:

For the long side: 5+3+10
And the short side: 4+3+4

If you've ever been to the boy scouts in Finland, you might know a song about those dimensions that's sung to the note of "old man noah":
viis-kolme-kymmenen / (fiv'-three-ten)
viis-kolme-kymmenen /
on pituus lipussa (is the length of the flag)
(repeat)

neljä-kolme-neljä / (four-three-four)
neljä-kolme-neljä /

viis-kolme-kymmenen /
viis-kolme-kymmenen /
on pituus lipussa
I think that's how it went.. My memory is a little shady as it's been a long time. :-)

I still am with the boy scouts mind you.