Every supplier will provide a starting point of how much FO (fragrance oil) you can use in your soy candles. The amount needed to create a strong soy candle will depend on a few factors such as:
Always weigh your FO's because each FO will vary in weight so you cannot use volume as a measurement and expect to get accurate results. We like to use percentages when weighing our FO's because we get consistent results no matter what size candle we are creating. For example if I know I will need 16 oz. of wax, then we take 16 and multiply that by our percentage of 9% (.09) which means I will add 1.5 oz. (1.44 rounded up) of FO for that candle (or per pound).
For larger candle batches the easiest way to figure out the amount of FO needed is to take your entire batch of soy wax and multiply that by your percentage. For example if you are creating four 16 oz. candles, you will take 64 oz. of wax and multiply that by 9% to come up with 5.75oz. of FO that you will need.