In general, a 1925 half dollar in good condition is worth around $10. A coin in very good condition is worth around $15, while a coin in excellent condition is worth around $20. A coin in uncirculated condition is worth around $50 or more.
The most valuable 1925 half dollars are those with the "S" mintmark from the San Francisco Mint. A 1925-S half dollar in uncirculated condition can be worth up to $100 or more.