How to Calculate the Amplitude of a Wave

🌊 Amplitude tells you how “tall” a wave is — and it’s one of the most important things to understand in wave physics.

Whether you’re learning about sound, light, or ocean waves, amplitude helps describe how strong or intense the wave is. The good news? It’s easy to calculate once you know what to look for.

Let’s break it down step by step.

🙋‍♀️ What Is Amplitude?

The amplitude of a wave is the maximum distance the wave moves from its rest (or equilibrium) position. Think of it as how high or low the wave reaches compared to the middle.

If you picture a wave on a graph:

  • The rest position is the flat middle line
  • The crest is the highest point
  • The trough is the lowest point

Amplitude measures the distance from the rest position to the crest (or trough).

It’s always a positive number and is usually measured in meters, volts, or decibels — depending on the type of wave.

🧮 Amplitude Formula

Here’s the simple formula:

Amplitude = (Maximum value – Minimum value) / 2

Or visually:

Amplitude = Distance from center to peak

If you have the total height of the wave from top to bottom, just divide that by 2 to get the amplitude.

📋 Example

Let’s say you’re analyzing a sound wave and see that the wave goes from +4 volts to –4 volts.

Using the formula:

Amplitude = (4 – (–4)) / 2 = 8 / 2 = 4 volts

✅ The amplitude is 4 volts

📡 Where You’ll Use Amplitude

  • Sound waves (louder = higher amplitude)
  • Radio signals
  • Light waves (brightness = amplitude)
  • Ocean waves
  • Electronics and oscilloscopes
  • Physics experiments

✅ Quick Tips

  • Amplitude = half the wave height
  • Always measured from the center line
  • Bigger amplitude = more energy in the wave
  • Works the same for sine waves, square waves, and real-world signals