Our Lux to Lumens Calculator converts illuminance in lux into luminous flux in lumens by considering the illuminated area. It helps you quickly estimate how much total light a space needs without confusing brightness per square meter with the total light output of a bulb or fixture.

Lux to Lumens Calculator

Convert illuminance in lux into the total light output needed in lumens.

Enter the lighting level you want
lux
Enter the room or surface area
Choose the unit used for your area
Your Lighting Result
Required Light Output
9,290 lumens
Illuminance 500 lux
Entered Area 200 ft²
Area in m² 18.58 m²
Light Output 9,290 lm
Formula: 500 lux × 18.58 m² = 9,290 lumens

How to Calculate Lux to Lumens ?

To convert lux to lumens, you need two values:

  • Illuminance: The amount of light falling on a surface, measured in lux (lx).
  • Area: The size of the illuminated surface, measured in square meters (m²).

For example, suppose a room receives 500 lux across an area of 20 m².

Lumens = 500 lux × 20 m²

Lumens = 10,000 lm

So, the space requires approximately 10,000 lumens to provide 500 lux across 20 square meters, assuming the stated illuminance applies uniformly across the entire area.

This calculation is useful for room lighting, office illumination, workshops, retail spaces, classrooms, garages, and other applications where you know the desired illuminance level.

Lux to Lumens Conversion Formula

The standard conversion formula is:

Lumens = Lux × Area

Or:

lm = lx × m²

Lux and lumens measure different things. Lumens (lm) describe the total visible light produced by a light source, while lux (lx) describes how much of that light reaches a given surface.

For example:

300 lux × 10 m² = 3,000 lumens

If the area doubles while the target illuminance stays the same, the required lumens also double.

Important: Area Is Required

There is no single fixed lux-to-lumens conversion because the illuminated area affects the result. A reading of 500 lux over 5 m² requires 2,500 lumens, while 500 lux over 50 m² requires 25,000 lumens.

The formula assumes an idealized uniform distribution of light. Real installations can produce different results because of fixture efficiency, beam angle, mounting height, room dimensions, surface reflectance, light losses, and the layout of the luminaires.

Lux to Lumens Conversion Chart

The table below shows the required lumens for common illuminance levels when the illuminated area is 1 m².

Lux

Area

Lumens

50 lx

1 m²

50 lm

100 lx

1 m²

100 lm

200 lx

1 m²

200 lm

300 lx

1 m²

300 lm

500 lx

1 m²

500 lm

750 lx

1 m²

750 lm

1,000 lx

1 m²

1,000 lm

1,500 lx

1 m²

1,500 lm

2,000 lx

1 m²

2,000 lm

For larger areas, multiply the lux value by the area. For example, 500 lux over 20 m² = 10,000 lumens.

How to Use Our Lux to Lumens Converter?

Using the calculator is straightforward:

  1. Enter the illuminance in lux.
    Enter the measured or desired light level, such as 300 lx or 500 lx.
  2. Enter the illuminated area.
    Provide the floor or surface area in square meters.
  3. Calculate the result.
    The calculator multiplies lux by area and displays the estimated luminous flux in lumens.
  4. Use the result for lighting planning.
    Compare the calculated lumen requirement with the total lumen output of your bulbs, LED panels, downlights, or other fixtures.

For example, if your target is 500 lux and the room measures 4 m × 5 m, the area is 20 m².

500 × 20 = 10,000 lumens

When checking lighting requirements, I recommend calculating the area first and then applying the target lux level. This simple step prevents one of the most common mistakes: treating lux and lumens as interchangeable measurements.

Why Should You Use Our Lux to Lumens Calculator?

Get a quick estimate of the total light output needed for a specific surface area and target illuminance level.

Quick Lighting Calculations

Calculate required lumens in seconds without manually applying the formula.

Avoid Lux and Lumen Confusion

Understand the difference between illuminance and luminous flux when selecting lighting.

Plan Room Lighting

Estimate lighting requirements for bedrooms, offices, kitchens, workshops, garages, and commercial spaces.

Check Existing Lighting

Compare your target illuminance with the approximate lumen output of your current lighting setup.

Frequently asked questions

Not always. 1 lux equals 1 lumen per square meter. Therefore, 1 lumen spread evenly over 1 m² produces 1 lux. The relationship changes when the illuminated area changes.

The formula is Lumens = Lux × Area in square meters. For example, 400 lux across 10 m² requires approximately 4,000 lumens.

No. You need the illuminated area because lux measures light received per unit area. Without the area, a direct lux-to-lumen conversion is not possible.

It depends on the area. For 10 m², you need approximately 5,000 lumens. For 20 m², you need approximately 10,000 lumens. The calculation assumes uniform illumination across the area.