How much can I contribute to solo 401k this year if I'm W2/1099?

[Amanda Larson]

Hello, 

I listened to a BP podcast tonight (show 162) with @AmandaHan about tax strategies for saavy real estate investors. The more I learn, the more questions I have! This question is regarding self-directed IRAs (SDIRAs) or solo 401K. In the podcast, it was said that a person can contribute up to $50,000/ year if you're self-employed, but only $5,000 if you're a W2 employee.  I am a full-time salaried W2 employee, but I also earn a small income on the side that is paid on a 1099 basis. So, my question is: Does the amount of earned 1099 income determine the amount the IRS allows me to contribute into an SDIRA? I assume that I cannot contribute more than I earned in 1099 income. 

Thank you for reading. Many more questions to come.