If I sell a stock for a profit that was partially held for less than one year and partially held for greater than one year, how much is the capital gains tax?

Note: For example, 50 shares of the stock have been held for greater then one year and 50 shares have been held for less than a year. If all shares are now sold, what is the capital gains tax rate? Short term or long term?

Investors & landlords

Both.  When you enter the sale you will have to split it into 2 sales.   One sale for the long term shares and another sale for the short term shares.  

Investors & landlords

the 2021 brokers' 1099-B will split the trade into a short-term and a long-term portions.