A lot of numbers I know, but it's pretty easy to internalize. For the majority, the formula is that each building which allows recruitment of a unit gives +2 cap, following tiers give +1.

Farms:
3 - 5 - 7 - 9 for all ashigaru

Bow Dojo:
2 - 4 - 6 - 8 for bow samurai
1 - 2 - 3 - 4 for specials (daikyu & bandits)

Temple:
1 - 2 - 3 - 4 for bow, naginata, marathon monks
0 - 0 - 1 - 2 for warrior nuns

Ikko Temple:
2 - 3 - 4 - 5 for bow, naginata
1 - 2 - 3 - 4 for marathon
0 - 0 - 1 - 2 for nuns

Cavalry:
2 - 2 - 3 - 3 for light cavalry
1 - 2 - 3 - 4 for others
0 - 0 - 1 - 2 for great guard

Yari:
2 - 3 - 4 - 5 for yari
1 - 2 - 3 - 4 for naginata, bulletproof

Sword:
2 - 3 - 4 - 5 for katana
1 - 2 - 3 - 4 for no dachi, wako

Siege Chain:
2 - 3 - 4 - 5 for fire bomb throwers
1 - 2 - 3 - 4 for matchlock samurai, mangonels, rockets

Ports - Gets kinda messy here. Nanban Port and Quarter do not provide additional caps for Japanese warships, so their number remains the same as Trading Port, but they give caps rather for trade ships, european units and imported matchlocks:

1 - 2 - 4 - 6 - 8 for bow kobaya

0 - 1 - 2 - 3 - 4 for medium bune

0 - 1 - 2 - 3 - 4 for siege tower

0 - 0 - 0 - 2 - 3 for sengoku

0 - 0 - 0 - 1 - 2 for firebomb kobaya

0 - 0 - 0 - 2 - 3 for heavy bune

0 - 0 - 0 - 1 - 2 for matchlock

0 - 0 - 0 - 0 - 1 for o ataka (base cap 2)

0 - 0 - 0 - 0 - 1 for cannon

0 - 1 - 3 - 3 [5] - 3 [7] for trade (base cap 2, brackets for Nanban Port and Quarter)