The color of a candle does not affect the amount of time it takes to burn. If the length of the wick and size of the candles are the same, they should burn for generally the same amount of time. However, other factors like wick size and the type of wax can have an impact on how long a candle burns for.
The dyes used to color candles are combined with the wax's oils and are not a factor in the amount of time it takes for a candle to burn, according to the National Candle Association. The dye has no impact on the fibers of the wick, and as long as that remains unaltered, a candle's burning ability is largely unaffected.
While a candle's color may not matter in a candle's lifespan, the size of the wick certainly does, as a larger wick provides more fuel for the flame and causes a candle to burn more quickly, as stated by Stefan Phillips of the Island Candle Company. One-fourth of an inch is the ideal length for a wick to prevent smoking and insure more efficient burning.
The type of wax can also affect the length a time a candle burns for because soft wax melts at a lower temperature, causing the candle to burn faster. The majority of candles in jars are made with soft wax, while pillar candles tend to be produced with hard wax and boast a longer burn time.