Headphone Power Calculator

Find amp power and voltage to drive headphones to a target loudness.

How the Math Works

The Headphone Power Calculator uses two key formulas to determine the electrical requirements for driving headphones. First, it calculates the power needed in milliwatts (mW) using mW = 10^((target − sensitivity)÷10), where 'target' is the desired sound pressure level (SPL) and 'sensitivity' is the headphone's efficiency rating (typically given in dB SPL at 1mW). This formula converts the difference between your target volume and the headphone's baseline efficiency into the precise power required. Next, it converts this power to voltage (V) using V = √(mW × impedance ÷ 1000), which applies Ohm's law to relate power, impedance (measured in ohms), and voltage for safe and efficient operation.

Practical Applications

To use this calculator, input your headphones' sensitivity rating (found in dB SPL/1mW in their specifications), your desired volume level (e.g., 100 dB SPL for a loud listening experience), and the headphone's impedance (in ohms). The calculator will output the required power in milliwatts and the necessary voltage from your amplifier. For example, if your headphones have 100 dB sensitivity, 110 dB target, and 32 ohms impedance, the tool will show you need 1000 mW power and 5.66 volts. Always compare these results to your amplifier's output specifications to ensure compatibility and avoid distortion or underpowered performance.

Day-to-Day Use

This calculator simplifies choosing the right audio equipment by revealing whether your current amplifier can drive your headphones to their full potential. It helps prevent common issues like weak volume from underpowered amps or distorted sound from overdriven ones. For instance, knowing your 32-ohm headphones require 1000 mW at 5.66 volts helps you select an amplifier rated for at least that output, ensuring optimal listening on devices like smartphones or high-end DAC/amps. It also aids in troubleshooting—if your headphones sound quiet, the calculator can quickly identify whether you need a more powerful source or if impedance matching is the issue, saving time and protecting your gear from damage.

Worked example

32 Ω, 100 dB/mW, 85 dB target → ~0.03 mW (very little).

FAQ