Let Me Do The Math For You: How Many Watts Of Power Does Your Body Generate?

TLDR Summary:

• Your body generates about 170 W of power when resting.
• A party with lots of people is like having a space heater running full time.
• Read more to see the math.

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The typical person consumes about 3500 calories per day. The term 'calories' is a lay person short-hand for 'food calories' which means 1000 actual calories as used in physics (1 'food calorie' = 1000 real calories). This means that a person actually consumes about 3,500,000 calories per day.

Converting to metric: there are about 4.2 joules (J) of energy in a calorie of energy. This means that you consume 14,700,000 J of energy per day.

A Watt (W) of power is defined as 1 J per second (J/s). We know that there are 86,400 seconds in a day. So if we divide 14,700,000 J by 86,400 seconds we get 170 Joules per second (or 170 W).

The (now old-fashioned) incandescent light bulbs ran on 100 W of power and were quite hot to the touch. You run at about 170 W (depending on your body size, metabolism and food intake) and have a much larger surface area so you are only warm to the touch (37°C to be exact).

Party Time

Imagine that you are having a party and have about 30 guests in your house. Each person puts out about 170 W, more if they are dancing. This means that at your party the guests are generating about 5,000 W. A typical electric room heater has a maximum power of 1500 W. This means the body heat of your party guests is like having 3 or 4 heaters running full time.

This is the math behind why parties get so hot even in the middle of winter.

Resources

1. My source for daily food intake