A rangefinder can help you determine the length of your drive and also how far you are away from the green. Although these devices can routinely cost between $200 and $300, their ability to provide accurate data is beneficial. When you know the average length you hit each club, you're more apt to select the right club and avoid under-hitting or over-hitting the ball. If you don't want to buy a range finder, it's possible to calculate the distance of your shots with a more traditional method.
Take your tee shot as per normal, and then find your ball and stand directly beside it.
Turn on the range finder, hold its sight to your eye and aim it directly at the flagstick. All range finders work slightly differently, but always include a sight that you aim at the flag. Note the reading on the range finder that indicates your distance from the flag.
Subtract the distance to the flagstick from the total yardage of the hole. For example, if the hole is 380 yards from the tees that you played and the range finder indicates that you're 120 yards from the flag, you hit your drive 260 yards.
Hit your tee shot and walk to the ball so you're directly beside it.
Pace off the distance to the nearest yardage marker. Yardage markers are situated throughout each hole and provide golfers with numbers indicating how far they are from the front or center of the green. For example, the golf course might have red markers to indicate 100 yards to the center of the green, or it may have yardages marked on the sprinkler heads.
Subtract the yardage to the green from the total yardage of the hole. For example, if the hole is 175 yards and you're close to the 50-yard marker, you hit your tee shot 125 yards. Most courses have markers every 50 yards.