Lumens is a mathematical formula that measures the bulbs intensity at 1 foot. The color or type of bulb is not calculated in the formula I=L/D²
Lumens received are a measured in watts-per-square foot or foot-candles. Calculating foot-candles or lux is a more accurate way to estimate the amount of light plants receive. This still only measures how much light you plants have available but not how much your plants use.
Light diminishes exponentially fast!
The closer your plants are to the light the more lumens they receive the better they will grow, as long as the heat from the light does not burn the foliage.