📐 How to Measure Knife Sharpening Angle

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 🔹 1. Using an Angle Guide Tool (Best for Beginners)

• Angle guides are small tools that rest under the blade to keep a consistent angle during sharpening.

• They’re available for 15°, 20°, and other common angles.

• Simply clip or rest the guide under the knife spine and sharpen as normal.

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✅ Best for: Whetstone and manual sharpeners.

🔹 2. Using a Smartphone App or Digital Angle Finder

• Apps like “Angle Meter” (iOS/Android) measure angle using your phone’s sensors.

• Place your phone flat on your sharpening stone, hold the knife against it and read the angle.

• Alternatively, a digital angle gauge can be used for precision (especially for guided systems).

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✅ Best for: Sharpening geeks or precision work.

🔹 3. Using the Coin Method (Simple Estimation)

• One US penny = approx. 1.5 mm thick.

• Stack coins under the spine of the knife while it rests on the stone:

  • For a 15° angle on a 1" wide blade, raise the spine about 0.25 inches (about 2 US pennies).

  • For 20°, raise it 0.34 inches (around 3 pennies).

Formula:
Height = Width × tan(Angle)
Example: For a 1" wide blade at 20° → 1 × tan(20°) ≈ 0.364"

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✅ Best for: Quick setup on flat stones.

🔹 4. Using a Sharpie Marker (Most Practical)

• Color the bevel with a Sharpie.

• Do a few light strokes on the sharpening surface.

• Examine where the marker is removed:

  • If it’s gone near the edge only, your angle is too low.

  • If it’s gone near the spine, it’s too high.

  • If it’s removed evenly across, your angle is just right.

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📌 Common Knife Edge Angles:

Use Case Angle    per Side     Total Angle

Razor / Paring      10–12°            20–24°

Chef’s Knife         15–20°             30–40°

Outdoor / EDC       20–25°           40–50°

Axe / Machete        25–35°            50–70°