Optimum Illumination/Lighting Calculator

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lm

Please check.

  • The number of lights required depends on the use of the space (studying, relaxing, etc.]. Since workspaces require higher illumination, please arrange them with some margin beyond the calculated value.
  • Selecting the color temperature (K] is important. Choose a product that matches the atmosphere of your space from Warm White (warm feeling], Cool White (ivory], and Daylight (white light].
  • When installing recessed lights (downlights], you must check the depth inside the ceiling (bays/ceiling space] in advance to prevent situations where product installation is impossible.
  • Consider separating the switch circuits. Controlling lights by zone is better for energy efficiency and creating atmosphere than turning them all on at once.
  • LED products may exhibit residual light. Please check the type of switch (lamp type, etc.] and install a residual light removal capacitor if necessary.

How about this calculator?

Optimal Illumination/Lighting Calculator, Guide to Calculating Essential Brightness (Lux] and Bulb Quantity by Space

How many watts should you use for a living room light to avoid eye strain? Lighting is not only the finishing touch to your interior but also a crucial element directly linked to eye health. Simply being brighter is not always better; you must adjust the appropriate illuminance (Lux] for the space's purpose to ensure eye comfort. If you select the room size and purpose (living room, study, bedroom, etc.], this calculator scientifically calculates the total brightness (lumens] required and the number of bulbs/lights you need to purchase, based on Korean Industrial Standards (KS] illuminance criteria.

Calculation formula for lighting quantity and illuminance

Calculate the total amount of light required for the space area, then convert it according to the bulb specifications.

Total brightness required
Required luminous flux (lm] = Area (m²] × Recommended illuminance (lx]
Required lighting quantity
Quantity Required (pieces] = Round up (Total brightness required ÷ Brightness of 1 bulb]

Divide the calculated sum of luminous flux by the brightness of a single bulb, and round up any decimal points to obtain the required number.


Detailed Guide to Calculator Input Items

Please check each item for accurate brightness calculation.

1. Space Use and Recommended Illumination

Select the location where you want to install the lighting. Recommended illumination levels are automatically set for each location, such as the living room (150lx], study room (300–500lx], and bedroom (70–150lx].

2. Room size and ceiling height

Enter the floor width and length in meters (m]. If the ceiling height is 2.5m or higher, brighter lighting is required due to light loss.

3. Bulb brightness and power consumption

Enter the luminous flux (lm] and power consumption (W] from the product detail page of the light bulb you wish to purchase. Checking the lumen value rather than the wattage is now more accurate for selecting brightness.


KS Recommended Illumination Standards by Space

space Activity details Recommended Illumination (Lux]
living room Conversation, watching TV, relaxation 150 ~ 300 lx
Study room / library Reading, studying, office work 500 ~ 1000 lx
Kitchen / Dining Table Cooking, meal, preparation 200 ~ 500 lx
bedroom Rest, getting ready for bed 70 ~ 150 lx

Expert Know-how and Checklists

This is the key know-how for creating a comfortable and three-dimensional space.

  • Distinguishing between Lumens (lm] and Watts (W]

    Watts represent electricity consumption, while lumens represent the actual brightness of the light. Since efficiency varies among LED products, you should check the lumen rating rather than the wattage to ensure accurate brightness when purchasing.

  • Select the appropriate color temperature (Kelvin] for the application

    Please select the lighting color according to the character of the space, such as warm white (3000K] for a cozy atmosphere, cool white (4000K] for a standard that is easy on the eyes, or daylight (6500K] for areas requiring high concentration.

  • Reduce eye strain with diffused lighting

    Arranging multiple lights, such as recessed lights and floor lamps, rather than turning on just one large light in the center of the room reduces shadows, makes it much more comfortable for the eyes, and makes the space appear three-dimensional.


Frequently Asked Questions (FAQ]

  • Q. Can I install it brighter than the calculated result?
  • A. Yes, the calculated value is the minimum recommended standard. You may install it about 1.5 times brighter depending on your personal preference, but to prevent glare, we recommend dividing the lighting circuit to adjust the brightness according to the situation.
  • Q. How many watts per square meter should I buy for LED lights?
  • A. In the past, it was calculated as 30 to 50W per square meter, but this is currently inaccurate. It is most accurate to check the total required brightness (lm] from the calculator results and select a product with a corresponding luminous flux.
  • Q. How is the calculation done for duplexes or commercial spaces with high ceilings?
  • A. If the ceiling height is 3m or higher, the light spreads out before reaching the floor. In this case, you must install it 1.5 to 2 times brighter than the calculated luminous flux or lower the light source using pendant lighting to ensure adequate illumination.