From 1903 to 1945, the Philippines was under U.S. administration, leading to a unique "hybrid" coinage. These coins feature "United States of America" on the reverse and "Filipinas" on the obverse. Most were struck at the San Francisco (S) or Philadelphia mints.
The "Great Size Reduction" occurred in 1907. Early Pesos (1903-1906) were massive 90% silver coins equivalent to Morgan Dollars. To prevent melting as silver prices rose, the U.S. shrunk the coins in 1907 and lowered the purity significantly.
| Coin | Purity | Years | ASW (oz) |
|---|---|---|---|
| 1 Peso (Large) | 90.0% | 1903-1906 | 0.7800 |
| 1 Peso (Small) | 80.0% | 1907-1912 | 0.5144 |
| 50 Centavos (Large) | 90.0% | 1903-1906 | 0.3900 |
| 50 Centavos (Small) | 75.0% | 1907-1945 | 0.2411 |
| 20 Centavos (Large) | 90.0% | 1903-1906 | 0.1558 |
| 20 Centavos (Small) | 75.0% | 1907-1945 | 0.0965 |
| 10 Centavos (Large) | 90.0% | 1903-1906 | 0.0779 |
| 10 Centavos (Small) | 75.0% | 1907-1945 | 0.0482 |
| 1 Peso (Roosevelt) | 90.0% | 1936 | 0.5787 |