The percent you are taking out is not the true tax rate. That is determined when you file the tax return.
The 20% is mandatory on a 401K withdrawal and I assume you chose the 7%.
You will need to estimate the taxable income for 2019, and then look at the tax rates.
You can do this by looking at the taxable income on the 2018 return and then estimate the amount you want to take out.
Take a look at this link: (The tax rates are the same for 2019)
https://turbotax.intuit.com/tax-tips/irs-tax-return/current-federal-tax-rate-schedules/L7Bjs1EAD
The percent you are taking out is not the true tax rate. That is determined when you file the tax return.
The 20% is mandatory on a 401K withdrawal and I assume you chose the 7%.
You will need to estimate the taxable income for 2019, and then look at the tax rates.
You can do this by looking at the taxable income on the 2018 return and then estimate the amount you want to take out.
Take a look at this link: (The tax rates are the same for 2019)
https://turbotax.intuit.com/tax-tips/irs-tax-return/current-federal-tax-rate-schedules/L7Bjs1EAD