Most people can obtain a visa on entry to Nepal. There are some countries where a visa will need to be obtained prior to traveling (you can find a list of these countries at www.immi.gov.np)
If you want to avoid the sometimes lengthy queues at the airport, you can obtain a visa from the Nepali embassy in you home country before you travel. Please visit the appropriate websites in your country for details.
If you want to obtain a visa on arrival, you will need to fill in a landing card, (most airlines provide these before landing in Kathmandu, if not, they will be available in the airport) pay a fee (cost differs depending on your length of stay) and provide a passport photo so don’t forget to bring one in your hand luggage to present to the immigration officers. Visa fees are as follows:
US Dollars 25 or other convertible foreign currency equivalent thereto for 15 days multiple entry visa.
US Dollars 40 or other convertible foreign currency equivalent thereto for 30 days multiple entry visa.
US Dollars 100 or other convertible foreign currency equivalent thereto for 90 days multiple entry visa.
(information from the department of immigration, Nepal)
We would advise you to bring US dollars to pay for your visa, most major currencies are usually accepted also. Although there is a currency exchange in the airport (if they will not accept your currency), you may not get the best exchange rate; therefore it is always a safe bet to bring US dollars.