Lux

Lux in Marine and LED Lighting Systems

Unit of Measurement

Definition
Lux (lx) measures illuminance, or how much light falls on a surface per unit area. It quantifies how effectively a light fixture illuminates a specific space, helping determine real-world visibility and brightness.

How Is Lux Measured?
One lux equals the illumination on a one-square-meter surface located one meter away from a light source. This provides a standardized way to evaluate how well light is distributed over an area.

Difference Between Lux and Foot-Candles
Both lux and foot-candles measure illumination, but they use different systems:

• Lux is a metric unit (lumens per square meter).

• Foot-candles belong to the imperial system (lumens per square foot).

To convert between the two:

• Foot-candles → Lux: Multiply by 10.764

• Lux → Foot-candles: Divide by 10.764

Why Lux Matters
While lumens indicate the total light output of a fixture, they don’t show how that light performs in real conditions. Lux reveals how efficiently light is distributed across a surface, accounting for factors like:

• Electrical efficiency

• Lens clarity

• Reflector design and geometry

• Beam angle

This makes lux critical when evaluating flood lights, deck lights, and underwater fixtures, where distance, spread, and direction drastically affect brightness and coverage.

Example of Lux in Practice
A marine flood light producing 7,000 lumens can deliver:

• 147 lux at 10 meters — similar to an overcast day

• 1 lux at 120 meters — comparable to full moonlight

• 0.25 lux at 240 meters — suitable for emergency or safety lighting

These values help visualize performance and make it easier to compare fixtures for marine environments where reliability and visibility are key.

Example in a Sentence
“The deck flood lights on my yacht deliver around 200 lux, providing bright, even illumination without glare during night docking.”

Synonyms: Lumens per square meter, Foot-candle

Related Terms:

• Lumen
  

• Beam Angle

• Luminous Efficiency

• Wattage

• Voltage Drop

   

• Operating Voltage
• Efficiency

Why Lux Matters for Marine Lighting

• Ensures safe light levels for night operations and maintenance

• Prevents glare and dark spots on decks and docks

• Helps choose the right beam pattern and mounting height

• Improves overall lighting efficiency and comfort onboard