Lumens per Watt Calculator

This calculator determines the luminous efficacy of a light source, measuring how efficiently it converts electrical power into visible light (lumens per watt).

Input Parameters

Calculation Results

Calculation Formula

Lumens per Watt (lm/W) = Lumens (lm) / Watts (W)

Where:
Lumens (lm): Total amount of visible light emitted
Watts (W): Electrical power consumed

Result

Lumens per Watt: 0.00 lm/W

Efficiency classification: N/A

Lumens per Watt Calculator Calculator Usage Guide

Learn how to use the Lumens per Watt Calculator calculator and its working principles

How to Use the Calculator

  1. Enter the total lumens (lm) emitted by your light source in the first input field.
  2. Enter the power consumption in watts (W) for the same light source in the second input field.
  3. Click the "Calculate" button to compute the lumens per watt (lm/W) value.
  4. The result will show the luminous efficacy of your light source, along with an efficiency classification.

Understanding Lumens per Watt (lm/W)

Lumens per watt is a measure of how efficiently a light source converts electrical power into visible light. It's one of the most important metrics for evaluating the energy efficiency of lighting.

Efficiency Classification

  • Low efficiency (<50 lm/W): Traditional incandescent bulbs
  • Medium efficiency (50-99 lm/W): Compact fluorescent lights (CFLs)
  • High efficiency (100-149 lm/W): LED bulbs, efficient fluorescent tubes
  • Very high efficiency (≥150 lm/W): Advanced LED technologies, laser lights

Example Calculation

If a light bulb produces 800 lumens and consumes 10 watts, the calculation would be:

lm/W = 800 lm / 10 W = 80 lm/W (Medium efficiency)

Why is Lumens per Watt Important?

Measuring lm/W helps you:

  • Compare the efficiency of different light bulbs
  • Save energy costs by choosing more efficient lighting
  • Reduce environmental impact through lower energy consumption
  • Make informed decisions about lighting upgrades