Compare the plug shapes, voltage and frequency in Czechia and Tonga, and find out which adapter you need before you travel.
Adapter required
Yes — coming from Czechia, you will need a travel adapter for Tonga. Czechia uses Type C/Type E plugs, and Tonga uses Type I, so the pin shapes will not fit any wall socket.
Czechia (home)
Tonga (destination)
Electrical specifications in Tonga
Voltage
Frequency
More about plugs in Tonga
In Tonga, the standard power plug is Type I. The country runs on 240 volts at 50 Hz. That means every wall socket in Tonga is the same shape — Type I, and your plug needs to physically match the socket to fit.
Full Tonga plug guide