Planetary Gear Calculator

- tsp
Last update 12 Jun 2026
Reading time 2 mins

Simple planetary gear set

Planetary Gear Calculator

Enter any two gear sizes. The calculator completes the geometry, evaluates the selected configuration, and draws the gear set.

Zr = Zs + 2Zp

01

Gear geometry

Enter any two tooth counts. Pitch diameters use d = m ยท Z.

SunExternal gear
PlanetExternal gear
RingInternal gear

02

Configuration

The input and output must be different members.

Fixed member

03

Transmission result

Input / output โ€”

Complete the geometry to calculate the ratio.

Output speedโ€”
Directionโ€”
Sun teethโ€”
Planet teethโ€”
Ring teethโ€”
Center distanceโ€”
Equation used

Willis equation: (ฯ‰s โˆ’ ฯ‰c) / (ฯ‰r โˆ’ ฯ‰c) = โˆ’Zr / Zs

04

Gear layout

Schematic pitch geometry. Tooth shapes are illustrative, not manufacturing profiles.

This article is tagged:

Related articles

Linear stepper motor control - A summary

A short summary of the algorithms required for linear accelerated and decelerated stepper motor control on microcontrolers.

Diode based passive RF frequency doublers - the basics

How can a simple passive circuit generate higher frequencies without oscillators or phase-locked loops? This short article explores the fascinating basics of diode-based RF frequency doublersโ€”circuits that exploit nonlinearities to produce harmonics, often with surprisingly broadband behavior and no need for biasing or active components. From a quick dive into the Shockley equation to typical basic circuit configurations like anti-parallel diode pairs and single-diode harmonic generators, this short article walks through both the math and the intuition behind passive frequency multiplication. Ideal for RF enthusiasts, circuit designers, or anyone curious about how this stuff works on a basic level.

Simple laser cutting and engraving capabilities for a 3D printer with a 450nm diode laser

This article summarizes some experiments using a simple 450nm laser diode on a 3D printer for some basic laser cutting and engraving in paper, plywood and other simple to cut materials.

PID control loop in a nutshell

Short dive into the basics of PID loops

Nuclear magnetic resonance and electron paramagnetic resonance: Basics

Nuclear Magnetic Resonance (NMR) and Electron Paramagnetic Resonance (EPR) are pivotal techniques used to explore molecular structures and dynamics through the magnetic properties of atomic nuclei and unpaired electrons. This article provides an introductory level examination of NMR, integrating both classical and quantum mechanical descriptions. Key topics include the Zeeman effect, Bloch equations, relaxation processes, and the quantum mechanical framework involving spin operators, Eigenstates, and the density matrix formalism. The discussion delves into the effects of RF driving fields, Rabi oscillations, and the incorporation of relaxation processes using the Lindblad master equation. The article concludes by demonstrating how these quantum mechanical models align with the phenomenological Bloch equations, providing a comprehensive understanding of the dynamics of spin systems under resonance conditions. While the primary focus is on NMR, the article also offers insights into EPR, broadening the perspective on magnetic resonance techniques.

Z, ABCD, S and T parameters in two port networks

A short summary about the different meaning and interpretation of impedance, ABCD, scattering and transfer parameters in simple (linear) two port networks.

Measuring the speed of light at Wiener Forschungsfest 2022

This article allows you to discover how we (a group from TU Vienna and University of Vienna) brought the fascinating world of physics to life at the Wiener Forschungsfest 2022! Using a visible range laser, a bicycle wheel, and modern photodiodes, we demonstrated how to measure the speed of light in an interactive and engaging setup designed mainly for children. This hands-on experiment highlighted the incredible speed of light while also conveying the fact that light is fast but not infinitly fast and allowed visitors to influence the accuracy of the measurement themselves. This article provides a short summary about the historical context, experimental setup, and the exciting outcomes of this educational outreach project.

A quick recap on Householder reflectors

This article is a quick summary on Householder reflectors in real values vector spaces and their application to zero rows or columns in matrices.

Also on this blog

Short Kalman filter summary

A short summary about Kalman filtering

Android development on FreeBSD

How to get started with Android development on FreeBSD (using Android Studio)

How to use Frama-C to proof C code (short primer)

A short primer on how to use Frama-C to proof properties about C-code.

Rรคumliche Verteilung bei endlicher Geometrie

Data protection policy

Dipl.-Ing. Thomas Spielauer, Wien (webcomplainsQu98equt9ewh@tspi.at)

This webpage is also available via TOR at http://rh6v563nt2dnxd5h2vhhqkudmyvjaevgiv77c62xflas52d5omtkxuid.onion/

Valid HTML 4.01 Strict Powered by FreeBSD IPv6 support