# Headphone Power Calculator

URL: https://speedycalculator.com/calculators/everyday-life/headphone-power/
Last updated: 2026-10-25

> The headphone power calculator works out the power, voltage and current an amplifier must deliver to drive headphones to a target loudness from their impedance and sensitivity (dB/mW or dB/V).

## Inputs

- Impedance (Ω)
- Sensitivity given as
- Sensitivity (dB)
- Target peak loudness (dB SPL)

## Results

- Sensitivity in dB/mW
- Power needed
- Voltage needed (RMS)
- Current needed (RMS)
- Maximum amp output impedance

## Formula

```
Sensitivity (dB/mW) = sensitivity (dB/V) + 10 × log₁₀(impedance ÷ 1,000)
Power (mW) = 10^((target dB − sensitivity dB/mW) ÷ 10)
Voltage = √(power × impedance); current = voltage ÷ impedance
```

## Explanation

Whether a phone or laptop can drive a pair of headphones depends on two specs: impedance (ohms) and sensitivity. Low-sensitivity, high-impedance headphones need more voltage, which small devices cannot supply. Aim for an amplifier output impedance under one-eighth of the headphone impedance for good damping. Listening at high levels for long periods damages hearing.

### How to use the Headphone Power Calculator

- **Impedance**
- **Sensitivity given as**
- **Sensitivity**
- **Target peak loudness**

Results update as you type, and every field accepts the units shown in its menu.

### How it works

Enter the headphone impedance, its sensitivity in dB per mW or dB per V and the peak loudness you want (110 dB SPL covers loud peaks).

### Tips

- Use the figures printed on your product or its manual when you have them.
- Round quantities up so you are never short.
- Measure twice before you buy anything cut to size.
- Everything runs in your browser – try different values to compare options.

### Common mistakes to avoid

- Mixing units (inches and centimetres, mAh and Ah).
- Ignoring efficiency losses and safety margins.
- Treating rules of thumb as exact.

### Inputs explained

FieldWhat to enterImpedanceIn ΩSensitivity given asChoose one: dB SPL per mW, dB SPL per VSensitivityIn dBTarget peak loudnessIn dB SPL

### What each result means

- **Power needed** = 10^(([Target peak loudness] - [Sensitivity in dB÷mW])÷10)
- **Voltage needed (RMS)** = sqrt([Power needed]÷1000×[Impedance])
- **Current needed (RMS)** = [Voltage needed (RMS)]÷[Impedance]×1000
- **Maximum amp output impedance** = [Impedance]÷8

### Example values

How the main result changes when **Impedance** changes and everything else stays at the example values above:

Impedance (Ω)Power needed (mW)161024103210401048106410

## Worked example

Inputs — Impedance: 32 Ω; Sensitivity given as: dB SPL per mW; Sensitivity: 100 dB; Target peak loudness: 110 dB SPL.

Results — Sensitivity in dB/mW = 100; **Power needed = 10 mW**; Voltage needed (RMS) = 0.566 V; Current needed (RMS) = 17.68 mA; Maximum amp output impedance = 4 Ω.

## FAQ

**Do I need a headphone amp?**
If the voltage needed is above about 0.5–1 V RMS or the power above 20–50 mW, most phones will struggle.

**What is a good sensitivity?**
Above about 100 dB/mW is easy to drive; below 90 dB/mW usually needs an amp.

**Is 110 dB safe?**
Only for brief peaks – average listening should stay well below 85 dB.

**What formula does the Headphone Power Calculator use?**
Sensitivity (dB/mW) = sensitivity (dB/V) + 10 × log₁₀(impedance ÷ 1,000).