Lux to Lumens Calculator
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Lux to Lumens Calculator
Lumens: N/A
Understanding Lux and Lumens
Lighting measurements can sometimes be confusing, but understanding the difference between lux and lumens is crucial for selecting the right lighting for any space. This calculator helps you convert illuminance (lux) measured over a specific area into the total luminous flux (lumens) emitted by the light source(s) covering that area.
What are Lux and Lumens?
- Lumens (lm): This is the SI unit of luminous flux, measuring the total amount of visible light emitted by a source. It quantifies the *total light output* of a bulb or fixture. When you see a light bulb rated at 800 lumens, it means the bulb itself emits that much light in all directions.
- Lux (lx): This is the SI unit of illuminance, measuring how much luminous flux is spread over a given area. It quantifies the *light falling on a surface*. 1 lux is equal to 1 lumen per square meter (1 lx = 1 lm/m²). Think of it as the *brightness of the light at a specific spot*.
How the Conversion Works
The relationship between lux and lumens is direct and based on the area over which the light is spread. The formula is:
Lumens = Lux × Area (in square meters)
In this calculator:
- You provide the measured illuminance in lux. This is typically measured using a light meter or lux meter at a specific point or averaged over an area.
- You provide the area in square meters (m²) that this illuminance covers.
By multiplying these two values, we determine the total luminous flux (lumens) required or produced by the lighting system to achieve that level of brightness over the specified area. This is particularly useful for:
- Determining the total lumen output needed for a room of a certain size to meet specific lux requirements (e.g., for offices, retail spaces, or task lighting).
- Estimating the lumen output of a light source if you know the lux level it creates on a surface of a known area.
Example Calculation
Let's say you measure an average illuminance of 300 lux on your desk. Your desk has an area of 1.5 square meters.
Using the formula:
Lumens = 300 lux × 1.5 m² = 450 lumens
This means the light source(s) illuminating your desk are providing a total of 450 lumens onto that specific surface area. If you were trying to achieve 300 lux in a larger workspace of 20 m², you would need a total luminous flux of 300 lux * 20 m² = 6000 lumens from your lighting fixtures.
function calculateLumens() {
var luxInput = document.getElementById("illuminanceLux");
var areaInput = document.getElementById("areaSqMeters");
var resultDisplay = document.getElementById("result").getElementsByTagName("span")[0];
var lux = parseFloat(luxInput.value);
var area = parseFloat(areaInput.value);
if (isNaN(lux) || isNaN(area) || lux < 0 || area < 0) {
resultDisplay.textContent = "Invalid input. Please enter positive numbers.";
return;
}
var lumens = lux * area;
resultDisplay.textContent = lumens.toFixed(2) + " lm";
}