Calculator Inputs
Formula Used
The calculator treats the blade section as part of a helix.
Pitch angle: θ = tan-1(P / 2πr)
Local circumference: C = 2πr
Selected radius from station: r = D / 2 × station / 100
Effective pitch: Pe = P × (1 - slip / 100)
Pitch from known angle: P = tan(θ) × 2πr
Here, P is geometric pitch. D is diameter. r is the selected blade radius. θ is the blade pitch angle.
How to Use This Calculator
- Enter the propeller pitch from a drawing, label, or design sheet.
- Enter the propeller diameter in the matching unit.
- Select station mode when the blade location is given as a percentage.
- Select direct radius mode when you measured the radius yourself.
- Add slip, RPM, and speed when you want operating estimates.
- Press the calculate button to show results above the form.
- Use CSV for spreadsheet work or PDF for a saved report.
Example Data Table
| Pitch | Diameter | Station | Radius | Estimated Pitch Angle | Use Case |
|---|---|---|---|---|---|
| 10 in | 12 in | 75% | 4.5 in | 19.49 degrees | Small marine propeller |
| 14 in | 16 in | 70% | 5.6 in | 21.69 degrees | Higher thrust setup |
| 8 in | 9 in | 80% | 3.6 in | 19.48 degrees | Model aircraft propeller |
Propeller Pitch Angle Guide
What The Angle Means
A propeller pitch angle links blade geometry with forward movement. It describes the angle between the blade section and the plane of rotation. A small angle gives gentle bite. A larger angle gives stronger axial travel, but it also needs more torque.
Why Pitch Angle Matters
A propeller is not flat. Each blade follows a helical path. The pitch value states the ideal forward distance for one complete revolution. The radius or station tells where the blade section is measured. These two values form a right triangle. The calculator uses that triangle to estimate the section angle.
Designers check the angle at several stations. The angle is high near the hub because the local circumference is small. The angle becomes lower near the tip because the path around the circle is longer. This twist helps the blade produce steadier thrust along its span.
Practical Inputs
The tool accepts pitch, diameter, blade station, direct radius, speed, revolutions per minute, and slip. Unit selectors help compare data from plans, lab sheets, and propeller charts. You can enter a station percentage when you know the blade location. You can enter a radius when your drawing gives direct measurements.
Speed and slip are optional. They help compare theoretical travel with practical advance. Slip shows the lost movement caused by water, air, load, and operating conditions. A high slip value may suggest overload, cavitation, ventilation, or poor matching.
Reading The Results
The main result is the pitch angle at the selected radius. The table also shows circumference, pitch ratio, station, effective pitch, theoretical advance, and tip speed. These values support quick comparisons between different propellers and operating cases.
Use the result as a geometry estimate. Real propeller performance also depends on blade area, airfoil shape, rake, cup, material, inflow, and fluid density. For final marine, drone, aircraft, or fan design, combine this calculation with test data and safety checks.
The export buttons save the current result. CSV is useful for spreadsheets. PDF is useful for reports, client notes, or classroom records. Recalculate with several stations to build a simple pitch angle map for the blade. For best practice, inspect the root, mid span, and tip sections. Compare every section against required thrust and available power.
FAQs
What is propeller pitch angle?
It is the blade section angle formed by pitch travel and local circular travel at a selected radius.
Which radius should I use?
Use the blade station where the section is measured. Many checks use 70% or 75% of tip radius.
Why does angle change along the blade?
Local circumference grows toward the tip. The same pitch therefore needs less angle at outer stations.
What does slip percent mean?
Slip is the difference between ideal forward travel and real travel. It depends on load and flow conditions.
Can this work for aircraft propellers?
Yes. The geometry formula works for air and water propellers. Performance still needs separate aerodynamic checks.
Can I calculate pitch from a known angle?
Yes. Enter a known blade angle. The tool returns the matching pitch for the selected radius.
Why enter RPM and speed?
They help estimate advance per revolution, tip speed, and observed slip during operation.
Is this enough for final design?
No. Use it for geometry estimates. Final design should include testing, strength checks, and safety review.