For bond ETFs, the 30-day SEC yield is the best measure as it approximates the yield if each bond in the ETF were held til maturity, which also assumes reinvestment of all income, accounts for expenses and considers the eventual dip in bonds at a premium. [Four Things You Should Know About High-Yield Bond ETFs]

All things considered, investors should still keep in mind that yields are a prediction of what will happen in the future and the figures should be taken with a grain of salt.

For more information on yield producing funds, visit our dividend ETFs or bond ETFs categories.

Max Chen contributed to this article.