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Complex Number Modulus Calculator

What Is the Modulus of a Complex Number?

The modulus |z| of a complex number z = a + bi is its distance from the origin on the Argand diagram, computed as |z| = √(a² + b²). This is a direct application of the Pythagorean theorem. The modulus is always a non-negative real number, and it equals zero only when z = 0.

Real component a in z₁ = a + bi

Imaginary component b in z₁ = a + bi

Real component c in z₂ = c + di

Imaginary component d in z₂ = c + di

Try an Example

Pick a scenario to see how the calculator works, then adjust the values

Signal Addition

Add two phasor signals in complex form to find the resultant.

Key values: z₁ = 3 + 4i · z₂ = 1 − 2i · Addition

Circuit Impedance

Divide two impedances to compute the transfer ratio.

Key values: z₁ = 3 + 4i · z₂ = 1 + 2i · Division

De Moivre Power

Raise a complex number to the 10th power using De Moivre's theorem.

Key values: z₁ = 1 + i · n = 10 · Power

Cube Roots of −8

Find all three cube roots of −8, visualized as equidistant points on a circle.

Key values: z₁ = −8 + 0i · n = 3 · nth Root

Documentation

This calculator is also known as Complex Number Modulus Calculator.

Read the complete guide

Modulus Formula

For z = a + bi, the modulus is |z| = √(a² + b²). This is the Euclidean distance from the origin (0, 0) to the point (a, b) in the complex plane. Key properties: |z| ≥ 0, |z| = 0 iff z = 0, |z₁·z₂| = |z₁|·|z₂|, and |z·z̅| = |z|².

Examples

Modulus of 3 + 4i

Find |3 + 4i|.

|3 + 4i| = √(9 + 16) = √25 = 5. This is the classic 3-4-5 Pythagorean triple.

Key takeaway: The modulus has a geometric meaning: it is the straight-line distance from the origin to the point (3, 4) on the Argand diagram.

Using the Modulus

Practical applications of the modulus:

  • Use |z|² = z·z̅ to avoid square roots when possible
  • In signal processing, |z| represents the signal amplitude
  • The triangle inequality |z₁ + z₂| ≤ |z₁| + |z₂| bounds the modulus of a sum

Frequently Asked Questions about Complex Number Modulus Calculator

Is the modulus the same as the absolute value?

Yes. For complex numbers, "modulus", "absolute value", and "magnitude" all refer to |z| = √(a² + b²). For real numbers, this reduces to the ordinary absolute value.

What is |z|²?

|z|² = a² + b² = z·z̅ (the product of z and its conjugate). This avoids the square root and is often more convenient in calculations.

Specialized Calculators

Choose from 11 specialized versions of this calculator, each optimized for specific use cases and calculation methods.

Operation

11 Calculators
add
Complex Number Addition Calculator | Add Complex Numbers Online
Add two complex numbers with step-by-step results in rectangular and polar form.
additionbinaryvector-sum
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subtract
Complex Number Subtraction Calculator | Subtract Complex Numbers
Subtract two complex numbers with results in rectangular and polar form.
subtractionbinary
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multiply
Complex Number Multiplication Calculator | Multiply Complex Numbers
Multiply complex numbers using FOIL or polar form. See the rotation and scaling on the complex plane.
multiplicationrotationscaling
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divide
Complex Division Calculator | Divide Complex Numbers Step-by-Step
Divide complex numbers by multiplying by the conjugate. See the step-by-step rationalization.
divisionconjugaterationalize
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modulus
Complex Number Modulus Calculator | Absolute Value of Complex Number
Calculate the modulus (absolute value) |z| of any complex number.
modulusabsolute-valuemagnitude
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argument
Complex Number Argument Calculator | Phase Angle Calculator
Calculate the principal argument (phase angle) of any complex number using atan2.
argumentphaseangle+1
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conjugate
Complex Conjugate Calculator | Find the Conjugate of a Complex Number
Compute the complex conjugate and see the reflection on the Argand diagram.
conjugatereflection
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power
De Moivre's Theorem Calculator | Complex Number Powers
Compute z^n for any integer n using De Moivre's theorem with polar form.
powerde-moivreexponent
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nthRoot
nth Root of Complex Number Calculator | Find All Roots
Find all n distinct nth roots of a complex number, displayed as equally-spaced points on a circle.
nth-rootroots-of-unityroot-circle
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modulus
Complex Number Converter | Rectangular to Polar Form
Convert complex numbers between rectangular (a+bi) and polar (r\u2220\u03b8) form with step-by-step work.
converterrectangular-to-polarpolar-to-rectangular
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add
Phasor Calculator | AC Circuit Impedance Calculator
Perform phasor arithmetic for AC circuit analysis. Add, subtract, multiply, and divide impedances.
phasorimpedanceengineering+1
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