About this calculator
Illumination is a physical quantity that measures the intensity of light, and its unit is lux. Illuminance represents the luminous flux received per unit area. The higher the illumination, the brighter the environment. Different places have different requirements for lighting. The illuminance calculator can help you design appropriate indoor lighting and ensure that illuminance meets standards. Our free online illuminance calculator provides a simple, fast and accurate solution.
The calculation formula of illumination is: illumination (lux) = luminous flux (lm) / area (m²). For example, for a 20 square meter room, using a 2000 lumen light bulb, the illumination = 2000 / 20 = 100 lux. Recommended illumination for different rooms: living room 100-300 lux, bedroom 75-150 lux, kitchen 300-500 lux, office 300-500 lux.
Using the illuminance calculator is easy and intuitive. Just enter the total luminous flux, room area and room type, click the calculate button and you will instantly get the illuminance and see if it meets the recommended standards. This tool is particularly suitable for interior lighting design, decoration and lighting renovation.
What it calculates
Illuminance calculator is based on the complete Chinese reference article for this calculator. It explains what the tool calculates, when to use it, and how the result relates to the underlying formula.
Formula
Use the formula shown by Illuminance calculator together with the values entered in the calculator. Keep units consistent and check any restrictions before interpreting the answer.
Inputs
Enter the required values for Illuminance calculator. Use numeric inputs where requested, keep variable names consistent, and review the selected unit or calculation mode before calculating.
- Required numeric values.
- Relevant units or variable names.
- Calculation mode or target value when available.
Example
A typical example uses simple values so you can compare the input, formula, and output. This helps verify that the calculator is being used correctly.
| Step | What to check | Purpose |
|---|---|---|
| 1 | Enter sample values | Confirm how Illuminance calculator reads inputs |
| 2 | Review the formula | Understand the calculation method |
| 3 | Compare the result | Use the answer correctly |
How to interpret the result
The result should be read together with the formula, input values, and any displayed calculation steps. If the calculator shows multiple values, compare each label before using the answer.
Common mistakes
Most mistakes come from missing units, entering values in the wrong field, or ignoring formula restrictions. Recheck the inputs if the result looks unexpected.
- Check units and signs.
- Do not leave required inputs blank.
- Confirm that the formula conditions are satisfied.
How to use
Using the illuminance calculator is easy. First, enter the total luminous flux (lumens) in the first input box. This is the sum of the lumens of all bulbs. For example, 3 800 lumen bulbs, total luminous flux = 2400 lumens.
Then, enter the room area in square meters. For example, the living room is 20 square meters and the bedroom is 15 square meters. Next, select the room type: living room, bedroom, kitchen, office, or bathroom. Different room types have different recommended lighting levels. Click the "Calculate" button.
The calculator displays the illuminance (lux) and the evaluation results. If the illumination is low, it is recommended to increase the number of bulbs or use brighter bulbs. If the illumination is high, reduce the number of bulbs or use darker bulbs to save energy. If the illumination is moderate, it means that the current lighting meets the standards. Click the "Reset" button to clear all inputs and start a new calculation.
Main features
This illuminance calculator has the following features: quickly calculates illuminance (lux); provides recommended illuminance for five room types: living room, bedroom, kitchen, office, and bathroom; automatically evaluates whether the illuminance is suitable; gives improvement suggestions; displays calculation formulas; automatically detects invalid input; simple and intuitive interface, easy to use; fast response speed, calculation results are displayed instantly; completely free, no registration or download required; supports desktop and mobile device access.
Use cases
The illumination calculator is very useful in several scenes. When designing indoor lighting, it can be used to determine how many bulbs are needed. For example, for a living room of 20 square meters, the recommended illumination is 200 lux, the total luminous flux required = 200 × 20 = 4000 lumens, and five 800 lumen bulbs can be used.
When decorating, it can be used to plan lighting solutions. For example, the kitchen requires higher illumination (300-500 lux), while the bedroom requires lower illumination (75-150 lux). When retrofitting lighting, it can be used to evaluate whether existing lighting is suitable. For example, the office illumination is only 150 lux, which is lower than the recommended value (300-500 lux), and additional light bulbs need to be added.
Can be used to optimize lighting during energy-saving renovations. For example, if the illumination in the living room is 400 lux, which is higher than the recommended value (100-300 lux), the number of light bulbs can be reduced to save energy. In lighting standard inspection, it can be used to verify whether the illumination meets the requirements. Whether you are designing, renovating or renovating, the illuminance calculator is a useful tool.