I am planning a trip to Vietnam and I was wondering if I need to buy a plug adapter or voltage converter. I am from the US and we use 110V; Vietnam uses 220V. Thank you in advance!
Unless your appliances are ancient they should tolerate 50-60 hz and 110-240 volts.
Have a look at the power supplies and chargers.
Your power adapters should have the fine print on them. If they say 120-240V, you're ok. Plugs in the US are either the flat type or 3-prong. Most sockets in Vietnam accept a number of different plugs, including US-type ones. Plug adapters are also widely available in local markets for about $2-3.Edited: 17 August 2018, 12:27