• Bathroom 70-80 foot candles. After the foot candles are determined, the next step is to decide how many lumens are needed in your space. A lumen is a measurement of light. So, if you are trying to light your 100 square foot dining room (which needs 30-40 foot candles), you will need 3,000-4,000 lumens in order to light that space efficiently. In order to find what kind of fixture can achieve this amount of lumens, just make sure to check the rated lumens based on the max wattage of the bulb and fixture as a whole. For example, a 4 light semi-flush mount that has a bulb max wattage of 60 and a fixture max wattage of 240 will have a rated lumen of 2,688.