Capital Gains Tax

HI, I would like to know approximately how much capital gains tax (on a house sale) I could anticipate paying in the following scenario.... House purchased in 1999 for $81,000. Dallas County Tax Assessors have based my property taxes on $481,000 sale price (their price, not a real estate agent). I am single so I assume that I will get a $250,000 deduction. i.e. $481,000 - 81,000 - 250,000= 150,000. So, what is the tax rate/capital gains on my scenario? And will that $250,000 deduction disappear after 2025? I am also trying to decide on whether to sell in 2025 or 2026. 

Thanks,

jf313