Moonlight Brightness Calculator

While the moon technically reflects light during the day, the Sun is roughly 400,000 times brighter. The calculator filters out sunlight to show purely lunar contribution. Additionally, during a Full Moon, the moon is exactly opposite the sun—meaning if the sun is up, the Full Moon is physically below the horizon.

The human eye is incredibly adaptive. Our night vision (scotopic vision) is logarithmic, meaning 0.25 Lux feels relatively bright to us in total darkness. In terms of raw electromagnetic energy, however, moonlight is very dim. For context, a typical living room is 50 Lux, while direct sunlight is up to 100,000 Lux.

No. This calculator estimates natural lunar illuminance. In a city, "Skyglow" (streetlights reflecting off clouds) can easily reach 0.1 to 0.5 Lux, overpowering the moon. In a city, clouds make the sky brighter; in nature, clouds make the sky darker. This tool assumes a natural, dark-sky environment.

When the moon is low on the horizon, its light must travel through a thicker layer of Earth's atmosphere ("High Air Mass"). This atmosphere scatters the blue light and absorbs intensity, which is why a rising moon looks orange and is significantly dimmer than a moon directly overhead.

Technically, yes, but it is difficult. The threshold for reading large print is roughly 0.20 Lux. A "Supermoon" (Perigee Full Moon) can reach ~0.30 Lux, which allows for reading headlines, but fine print requires color vision (photopic), which generally activates above 3.0 Lux.

The moon's surface is covered in porous, dusty soil (regolith). When lit from a sharp angle, these particles cast tiny shadows on each other, darkening the moon. When the sun is directly behind you (a Full Moon), those shadows disappear, causing a disproportionate spike in brightness known as the Opposition Surge.