The amount of calories you burn biking in 20 minutes depends on how much you weigh and how fast you cycle. A leisurely bike ride of 10 mph or less will burn fewer calories than cycling faster in a 20-minute period. A 150-lb. person biking at less than 10 mph will burn 90 calories in 20 minutes, according to the Calories Burned Biking website. By increasing the speed to 12 to 14 mph, that person will burn 198 calories in 20 minutes. A 200-lb. person will burn 120 calories with a leisurely bike ride, but traveling between 12 and 14 mph will burn 264 calories in 20 minutes. A 240-lb. person will burn 144 calories in 20 minutes, while more vigorous biking will burn 317 calories.

Cycling for 20 minutes a day is beneficial, as the Department of Health and Human Services recommends at least 2 1/2 hours per week of moderate activity, such as leisurely bike riding, or 1 1/4 hours of vigorous aerobic exercise, such as biking between 14 and 16 mph. In addition, a strength-training exercise is recommended at least twice a week. For weight loss, you may need to increase your activity more, according to MayoClinic.com.

You must know your time as well as distance covered to estimate how many calories you burn riding a bike three miles. Use your time and distance to figure your average speed. To calculate average speed, divide the distance covered by your time in minutes and multiply by 60. For example, if you ride three miles in 18 minutes, use this formula: 3/18 x 60 = 10 mph. Next, look on a chart of calories burned over time such as those provided by MayoClinic.com or NutriStrategy.com to estimate calories burned. These charts usually list calories burned for a full hour. To find the calories burned for other amounts of time, multiply the calories-burned estimate for your weight and speed by your time in minutes divided by 60. Suppose you ride a road bike for 18 minutes at 10 mph — three miles — and you weigh 155 lbs. You will burn 281 calories multiplied by 18/60, or about 84 calories.

**How Much Do You Weigh?**

When calculating the number of calories burned on an average bike ride, you’ll need to consider your weight. When it comes to biking–or virtually any other form of exercise–the more you weigh, the more calories you are likely to burn while engaged in cycling.

**How Fast do You Ride?**

The speed at which you operate your bicycle is another determinant factor in the number of burned calories you accumulate while biking. The faster you ride, the more calories you will burn. So when cycling, try to keep a swift, steady pace.

**How Long are Your Bike Rides?**

Lastly, you’ll need to take the length of your bike rides into consideration when determining how many calories you burned. Much like the previously discussed factors, longer bike rides will result in greater numbers of burned calories. So if you’re looking to lose weight, try to take long rides, albeit not excessively long ones.

Having considered the above-mentioned factors, you’re ready to determine the number of calories you burn while cycling. For example, if you weigh 120-175 pounds and bike at an average rate of 10 mph, you will burn 215-240 calories per half hour. If you weigh 200-250 pounds and bike at the same speed, you will burn 300-360 calories per half hour. If you weigh 300-350 pounds and bike at the same speed, you will burn 420-500 calories per half hour.