I have sold some land that was gifted to me by a family member. I am currently unemployed and want to determine how much I will need to pay in capital gains tax

How long did you own it?

without a lot more info such as holding period and taxable income without the gain and the gain no one can give you an amount. it could range from 0% to over 20%

Before we can tell you (and before you can file) you need to know:

1. What did your relative pay for the land? (This will be in the county records.)

2. When did they give it to you?

3. Was it farmland or timberland?  (Money-making land?).   Or something else.

4. Did you or the previous owner ever elect to "capitalize your carrying costs."  (If you don't know, the answer is "no".)

5. Did you and the previous owner together, own the land for more or less than one year (you combine both periods of ownership).

6. What was the selling price.

7. What is your other income for the year?

8. What is your marital status?

9. Do you have any dependents?

Now, I am going to make 4 assumptions to give you a rough guess of one scenario.  If we assume that,

a. you have no idea what the purchase price was and can't prove anything, and

b. you will have no other income for all of 2022, and

c. you are single with no dependents, and

d. you owned the land more than one year

Then this is how the sale will be taxed.

a. the entire selling price is your taxable capital gain

b. the first $41,000 is tax-free

c. the next $417,000 is taxed at 15%

d. anything over $459K is taxed at 20%.

But your result may be very different depending on your other facts.