There are multiple factors which influence the exchange rates of a country. These may include inflation, current account deficit, interest rates, public debts, trade between the countries and economic position of the country as well as currency. These rates change very often as they float in the currency market freely against one another which leads to contact change in the exchange rates. Similar is the Nigerian currency Naira (NGN) which is highly flexible and changes frequently against the US Dollar.

Every money transfer company has its own upfront fees and exchange rate cost which will lead you to pay more for foreign exchange. No matters where you send money, people always end up with paying higher fees including hidden fee and commission. So, if you want to transfer money from the US to Nigeria, first you must compare all the companies and then check out which one is offering better rates along with lower transfer fees. 

While money reached to your loved ones chiefly depends upon the exchange rate, there are some ways by which you can reduce the fees and this will get you the "cheapest transfer rate for Nigeria from the USA". But again the question arises is which is the “best money transfer company” according to your needs and requirement of the recipient. So, here are a few base points which you should consider before transferring US Dollar to Nigerian Naira:

1. Speed: How soon you want your money to reach the recipient? There are many companies which offer instant or same day money transfers. Western Union, MoneyGram and Ria Money Transfer are among some of such companies which have a worldwide network of agents and helps in transferring money real soon. But if you have enough time and no emergency is hitting, you can send it through other companies such as WorldRemit, Transfast, Xoom and Remitly.
2. Exchange Rate: Almost all the companies which offer money transfer services to Nigeria plays with the exchange rate by deducting profit margin, commission and other hidden fees. Still, companies have different exchange rates so you must compare the mid-market exchange rates, bank rates and other transfer services which will spare you from paying some extra bucks. In this search you may also find some of such companies which will let you send money to Nigeria for free.
3. Fees and Other Taxes: There are taxes levied on every transfer depending upon the policies of both the countries which will be deducted from the amount paid. For example, you are not allowed to transfer amount more than USD$10,000 and if you do, you need to take the permission of federal law of America which also levy extra taxes on the sender. 
4. Transfer Convenience: If one can transfer in an easy way without any support of customer assistance, then the company is considered as highly convenient. You can make transfers online without physically visiting its office. In the era of digitalization, mobile apps are also necessary which can ease the transfers anytime anywhere. Xoom Money Transfer, Remitly, WorldRemit and Trasfast offer bank account to bank account transfer while Xoom also offers cash pick-up services, airtime top-up, cash delivery at home and bill payment solution to its customers. So, those who want to use other services can make money transfer through Xoom. Other than this, Remitly, WorldRemit, Transfast, Xoom Money Transfer etc. are also offering their mobile apps.

There are multiple companies providing remittance services from the US to Nigeria, but it is not necessary that it will provide you with the best available services. It is most essential for the sender to take charge and be aware of hidden and transfer fee along with the exchange rates provided by them as well as competitors. So, you should invest your time and explore the best keeping the following factors in mind:

Reliability: Check the user reviews of the company provided by its customers on multiple websites. This will help you to know how the services of company are and it is not a fraudulent business.

Plan the Transaction: If there is no emergency, then you must plan your transfer earlier, so that it will reach to the recipient within 3-5 days.

Customer Service: Having a helping hand at the time of transferring funds is beneficial if in case you face any difficulty. The reputable companies offer best customer support in the event of mishap like delay or non-arrival of funds.

1. Remitly
2. WorldRemit
3. TransferWise

1. World Remit
2. Xoom

1. Western Union
2. Money2Anywhere

1. Bank of America
2. Citibank

1. TransferWise
2. WorldRemit
3. Transfast