All Science Fair Projects

Over 1000 FREE Science Fair Project Ideas!

Comparing the burning speed of scented and unscented candlesFeatured science projectScience project video


- The materials required for this science project5 unscented candles
- 5 rose scented candles
- 5 apple scented candles
All of the 15 candles should have the same diameter, length and  be made by the same manufacturer
- A ruler
- A caliper
- A stopwatch
- A box of matches or lighter


1. For this experiment, the independent variable is the type of candle used – unscented, rose scented and apple scented. The dependent variable is the reduction in the candle’s length after 30 minutes. This is determined by measuring the height of the candle before and after allowing it to burn for 30 minutes. The constants (control variables) are the length of the candle, the diameter of the candle, the allowed burn time and the room temperature.

2. The three types of  candles are labeled  according to  their scents and  numbered   from 1 to 5 for each type. Their total length and diameter is measured using a ruler and caliper for comparison. Any candle found to have a deviation of more than 1 mm in diameter is replaced with a new candle. All of the candle heights are recorded.

3. All 15 candles are lighted up and the stopwatch is started. After 30 minutes, the candles are  snuffed out in the same order that they were lighted up earlier. The lengths of all the 15 candles are measured once more using the ruler.

4. The length of candle that was burned up in the 30 minutes is calculated by deducting the final length of the candle from its original length. The results are recorded in the table given below.

See our all-time most popular science projects
Search science fair projects Browse science fair projects
popular science fair projects
Complexity level:
Project cost ($):
Time required:
1 hour to prepare, 1 hour for the science project experiment
Material availability:
Easily found. Candles can be purchased at a supermarket or department store.
Safety concerns:

Be careful when handling fire. Ensure that the experiment is conducted in a well-ventilated laboratory or in a safe location, with no flammable materials lying around. Adult assistance is required.