Compatibility summary
Your Thailand plug may fit in San Marino outlets, as both use at least one common plug type.
Plug comparison
Thailand plug types: A B C O
San Marino plug types: C F L
Both countries share at least one plug type (A B C O and C F L), so some plugs may work without an adapter. Check your appliance.
Voltage comparison
Thailand: 220V, 50Hz
San Marino: 230V, 50Hz
Voltage difference is within a range many devices tolerate; check your appliance label.