Does anyone know how to calculate one's Self Employment tax easily?

Do you have 1099NEC or self employment income?  You pay Self Employment tax (Scheduled SE) on a Net Profit of $400 or more on Schedule C.  You pay 15.3% SE tax on 92.35% of your Net Profit (If it is greater than $400).  The 15.3% self employed SE Tax is to pay both the employer part and employee part of Social Security and Medicare. 

FOR ESTIMATES.....

You must make quarterly estimated tax payments for the current tax year if both of the following apply:

- 1. You expect to owe at least $1,000 in tax for the current tax year, after subtracting your withholding and credits.

- 2. You expect your withholding and credits to be less than the smaller of:

    90% of the tax to be shown on your current year’s tax return, or

  100% of the tax shown on your prior year’s tax return. (Your prior year tax return must cover all 12 months).