Converting millicandela (mcd) to lumens (lm) is essential for understanding the total light output of an LED, especially when the beam angle is known. Luminous flux, measured in lumens, represents the total amount of visible light emitted by a source, while luminous intensity, measured in candelas or millicandelas, indicates the brightness in a specific direction. The relationship between these units is defined by the formula: Φv = Iv × Ω, where Φv is the luminous flux in lumens, Iv is the luminous intensity in candelas, and Ω is the solid angle in steradians. To calculate the solid angle, use Ω = 2π(1 - cos(θ/2)), with θ representing the beam angle in degrees. By inputting the luminous intensity and beam angle into a millicandela to lumens calculator, users can accurately determine the total light output of LEDs for various applications.