Compass Rule Adjustment Calculator

This calculator helps adjust compass readings by accounting for magnetic declination and other factors affecting compass accuracy

Input Parameters

East is positive, West is negative

Calculation Results

Adjusted Compass Course

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Calculation Formula

Adjusted Course = Magnetic Course ± Declination ± Compass Error

Where:
True Course: The intended direction as shown on a map
Magnetic Course: The direction your compass indicates
Magnetic Declination: The angle between magnetic north and true north
Compass Error: Systematic error in your compass reading

Important Notes

Compass declination changes over time and location. Always verify with local surveys for accurate navigation.

Compass Rule Adjustment Calculator Usage Guide

Learn how to use the Compass Rule Adjustment Calculator for accurate navigation

How to Use This Calculator

  1. Enter your True Course - the direction you intend to travel based on a map
  2. Enter your Magnetic Course - the direction your compass indicates
  3. Enter the Magnetic Declination for your location. Use a positive value for east declination (where magnetic north points east of true north) and a negative value for west declination
  4. Optional: Enter any Compass Error if your compass consistently deviates from true readings
  5. Click the Calculate button to see your adjusted compass course

Understanding Compass Declination

Magnetic declination is the angle between magnetic north (the direction your compass needle points) and true north (the direction on a map). This difference varies by location and changes over time due to shifts in the Earth's magnetic field.

Example Scenario

You're planning a hike. Your map shows a true course of 90° (east). Your compass reads 95°. In your area, the magnetic declination is 3° east. To adjust your compass:

  • True Course: 90°
  • Magnetic Course: 95°
  • Declination: +3° (east)
  • Compass Error: 0°
  • Adjusted Course: 95° + 3° = 98°

Set your compass to 98° to travel east on your map.

Applications

This calculator is essential for outdoor enthusiasts including hikers, backpackers, and surveyors who rely on accurate compass navigation. It's particularly useful in areas with significant magnetic declination.