This article was machine-translated from the Korean original. Read the Korean original
In my last column, I shared a formula for reading slopes as percentages using a 100cm ruler. Today, I will show you a practice method to help you internalize that formula so you can use it immediately in real-world situations. It is a training exercise where you can estimate the percentage just by looking at the slope, without a ruler.
The standard distance is 90cm. Interestingly, this 90cm matches the length of your putter almost perfectly. A 34-inch putter is about 85.5cm, and if you add just one ball (about 4.5cm) to that, you get exactly 90cm. If you learn this method, you will eventually be able to measure distances using only your putter, without a ruler.
01Practice reading slopes from a distance of 90cm
Place the ball 90cm from the entrance of the hole, lay a ruler horizontally at the midpoint, and lower yourself to observe. You just need to ask yourself two things — which side is higher and lower, and what percentage.
- Lay down and lower your bodyYou must place the ruler horizontally in the middle at the 90cm mark, step back sufficiently, and lower your posture to see the slope properly. Many people do this out of habit without knowing why they need to assume this position, but this distance and eye level are essential to accurately see the ruler's incline.
- Predict and try out using percentagesVisually estimate the slope percentage, then set your target and hit the ball using the formula you learned earlier. Since this formula is based on a speed of about 60 to 80 cm past the hole, you must adjust your speed accordingly.
- Verify the result and save againIf your prediction is correct, save that feeling; if it is wrong, sit back down and look again, thinking, "Ah, this wasn't 2%, it was 3%." This process itself trains your eyes.
- Repeat randomly by changing the angleInstead of staying in the same spot, try repeating the exercise while changing your direction and angle. This trains your eyes much more evenly than practicing looking from only one side.
02Without a ruler, just like in the real thing
Once you get used to practicing with a 90cm ruler, move on to the stage of predicting solely through imagination without the ruler. You will experience how surprisingly accurate it works when you predict, "The left side is higher, it's 2%," and then hit the ball. When you reach this point, you will have perfected a short putting routine that can be used in actual play—stepping back behind the ball to check the elevation and executing a stroke that matches the percentage.
03Distances exceeding 90cm are like this
For every 30cm increase in distance from the 90cm target, the target moves a little further. You can think of it as 2cm for 1%, 3cm for 2%, and the size of one ball continuously increasing for 3%.
| distance | 2% slope | 3% slope |
|---|---|---|
| 90cm | 1cm outward from the high edge of the hole | One ball outside the high edge of the hole |
| 120cm | 4cm outward from the edge | Two balls outside the edge |
| 150cm | 7cm outward from the edge | 3 balls outside the edge |
I recommend using this formula only up to 1.5m (150cm). Beyond that, the irregularity of the green increases, so the formula does not match 100%. Of course, if you are a player with excellent feel, you can use it as a rough guide up to 10m, but even then, you should use it not as the definitive answer, but merely as a rough compass to decide "to estimate a bit more or less."
04Organizing today
Start by placing a ruler at a distance of 90cm and making eye contact. Once you get used to it, practice without the ruler, relying on your imagination. Then, gradually increase the distance to 120cm and 150cm. If you repeat this sequence, you will be able to read the green much more confidently during a round.
