Lux to Lumens Calculator
Convert illuminance (Lux) to luminous flux (Lumens) for a given area.
Understanding Lux and Lumens
Illuminance and luminous flux are two fundamental concepts in photometry, the science of measuring light. While both relate to light output, they describe different aspects:
- Lux (lx): Lux measures illuminance, which is the amount of luminous flux (light) falling on a specific surface area. It tells you how brightly a surface is lit. One lux is equivalent to one lumen per square meter (1 lx = 1 lm/m²).
- Lumens (lm): Lumens measure luminous flux, which is the total quantity of visible light emitted by a source per unit of time. It quantifies the total light output of a bulb or fixture, regardless of the direction it's emitted or how much hits a surface.
The Conversion Formula
The relationship between lux, lumens, and area is straightforward. To find the total luminous flux (in lumens) received by a surface, you multiply the illuminance (in lux) by the area of the surface (in square meters).
This calculator uses this direct relationship. By inputting the illuminance level (Lux) you want to achieve on a surface and the size of that surface (in square meters), it calculates the total luminous flux (Lumens) required from your light source(s) to meet that illuminance target.
When to Use This Calculator
This tool is invaluable for:
- Lighting Design: Architects, interior designers, and lighting engineers use it to specify the correct lumen output for lamps and fixtures needed for a particular room or area to meet recommended lighting standards. For instance, a workspace might require 500 lux, while a hallway might only need 100 lux.
- Homeowners: Planning lighting for a new room, renovation, or even outdoor spaces. You can determine how bright your lights need to be by calculating the total lumens needed for your specific area.
- Facility Management: Ensuring adequate lighting levels in commercial, industrial, or educational settings for safety, productivity, and comfort.
- Understanding Light Specifications: Helping to demystify technical specifications of light bulbs and fixtures, relating their total light output (lumens) to their effect on a lit area (lux).
Example Calculation
Let's say you are designing the lighting for an office meeting room that measures 5 meters by 8 meters. You want to achieve an illuminance level of 500 lux on the desks and floor for comfortable working conditions.
- Area: 5 m × 8 m = 40 square meters
- Desired Illuminance: 500 lux
Using the formula:
This means you would need a total of 20,000 lumens from your light fixtures distributed across the room to achieve an average illuminance of 500 lux. You might achieve this with multiple smaller fixtures or a few higher-output ones, depending on the desired light distribution and aesthetics.