Light Intensity Calculator - Free Online Tool

This Light Intensity Calculator provides a seamless conversion platform for various photometric units, making it essential for accurate lighting design and photography. Whether you are working with lux (the SI unit), foot-candles (common in US building codes), or lumens per square meter, our tool handles the complex mathematical relationships instantly.

Simply input your measurement into the desired unit field. The calculator automatically converts it using established industry formulas. For example, if you know a surface is illuminated at 50 lux, entering that value will immediately display its equivalent in foot-candles (approximately 5 lumens/ft²), allowing you to compare specifications across different global standards.

This ensures that your lighting plans—whether for retail displays or architectural installations—are based on consistent, comparable data points, eliminating the guesswork from manual conversion tables.

To get the most accurate and useful results from this calculator, consider integrating it into your workflow at multiple stages. Don't wait until the end of a project to measure light.

• Measure at Source vs. Target: Always record both the source output (lumens/watt) and the target illuminance (lux) to fully understand the system efficiency.
• Account for Angles: Remember that light intensity drops off rapidly with distance, following the inverse square law. Use your knowledge of this principle when scaling measurements.

When shooting photos, take reference readings in both lux and foot-candles to ensure consistency if you are mixing different lighting sources or working across varied geographical standards.