Modulus of Complex Number Calculator

Calculate complex magnitude with detailed steps for every input. Compare modulus, argument, and squared value. Export results, review examples, and learn formulas with graphs.

Calculator Inputs

Example: 3, -8, 0.45
Enter the coefficient of i.
Overrides a and b when filled.
Use one value per line. Supported examples: 3,4 or -5 12 or 7-2i.

Complex Plane Graph

The graph plots the complex number as a point and vector. The circle shows the same modulus distance from zero.

Formula used

For a complex number z = a + bi, the modulus is the distance from the origin to the point (a, b).

|z| = √(a² + b²)

|z|² = a² + b²

arg(z) = atan2(b, a)

conjugate(z) = a - bi

unit(z) = z / |z|, when |z| ≠ 0.

How to use this calculator

  1. Enter the real part in the first box.
  2. Enter the imaginary coefficient in the second box.
  3. Use the optional text field when you already have a value like 6-8i.
  4. Select decimal places, angle unit, and output style.
  5. Add batch values when you want to compare many complex numbers.
  6. Press the calculate button. The result appears above the form.
  7. Use CSV or PDF download buttons to save the result.

Example data table

Complex number a b Formula Modulus
3 + 4i34√(3² + 4²)5
-5 + 12i-512√((-5)² + 12²)13
8 - 15i8-15√(8² + (-15)²)17
1 + 1i11√(1² + 1²)1.4142

Why Modulus Matters

The modulus of a complex number is its distance from the origin. It turns a two part value into one clear size. This size helps in algebra, geometry, signals, circuits, and vectors. A complex number has a real part and an imaginary part. The real part moves along the horizontal axis. The imaginary part moves along the vertical axis. Together, they form a point on the complex plane.

Reading the Result

This calculator gives more than the main magnitude. It also shows the squared modulus, argument, conjugate, unit complex number, and reciprocal. These values are useful when checking roots, scaling phasors, comparing vectors, or simplifying expressions. The squared modulus is often faster in proofs. It avoids a square root and still compares size correctly. The unit complex number keeps the same direction, but its length becomes one.

Graph and Interpretation

The graph shows the input as a vector from the origin. The circle marks all points with the same modulus. This helps explain why different complex numbers can have the same magnitude. For example, 3 + 4i and -3 - 4i both have modulus 5. They point in opposite directions, but they sit the same distance from zero. Batch points make comparisons easy.

Practical Learning Use

Use this tool when solving homework, preparing examples, or checking manual work. Enter decimal, negative, or zero values. Choose the precision that matches your class or project. Switch angle units when you need degrees or radians. Export the result when you want a record. The CSV file is useful for spreadsheets. The PDF file is useful for notes or reports.

Accuracy Notes

The formula follows the Pythagorean theorem. Very large values may round in normal browser display. The calculator still keeps the process transparent. Each result includes the values used in the formula. That makes mistakes easier to find. Always check signs before entering the imaginary part. A negative imaginary value changes the argument, even when the modulus stays positive.

Good Workflow

First estimate the answer by eye on the plane. Then calculate the exact value. Finally compare the graph, table, and formula line. This habit builds accuracy and confidence during repeated practice sessions.

FAQs

1. What is the modulus of a complex number?

The modulus is the distance of a complex number from the origin on the complex plane. For z = a + bi, it is √(a² + b²).

2. Can the modulus be negative?

No. Modulus is a distance, so it is always zero or positive. Only the zero complex number has modulus zero.

3. What is the modulus of 3 + 4i?

It is 5. The calculation is √(3² + 4²), which becomes √25. The final value is 5.

4. Does the sign of the imaginary part affect modulus?

The sign does not change the modulus if the absolute size is the same. For example, 3 + 4i and 3 - 4i both have modulus 5.

5. What is squared modulus?

Squared modulus is a² + b². It is the modulus before taking the square root. It is useful for comparisons and algebraic simplification.

6. What happens when z equals zero?

When z = 0 + 0i, the modulus is zero. The unit complex number and reciprocal are undefined because division by zero is not allowed.

7. Can I enter many complex numbers?

Yes. Use the batch box. Add one complex number per line, such as 3,4 or -5 12 or 7-2i.

8. Why is the graph helpful?

The graph connects the formula to geometry. It shows the point, the vector from zero, and the circle with the same modulus.

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.