Similarly, if someone tells you that the temperature is 85 degrees Fahrenheit, you’ll probably wear a bathing suit or shorts. And if they tell you it’s 40 degrees Fahrenheit, you’ll probably wear a coat. But what do you wear if they tell you that the temperature is 25 degrees Celsius?

Here you will learn a few rules of thumb to estimate metric amounts. In each case, you will see how a common metric unit compares with an English unit that you already feel comfortable with.

## Estimate distances and speed

**Here’s how to convert meters to feet:**1 meter is approximately 3.26 feet. But for estimating, use the simple rule that 1 meter is about 1 yard (that is, about 3 feet).

By this estimate, a 6-foot man stands about 2 meters tall. A 15-foot room is 5 meters wide. And a football field that’s 100 yards long is about 100 meters long. Similarly, a river with a depth of 4 meters is about 12 feet deep. A mountain that’s 3,000 meters tall is about 9,000 feet. And a child who is only half a meter tall is about a foot and a half.

**Here’s how to convert kilometers to miles:** 1 kilometer is approximately equal to 0.62 miles. For a ballpark estimate, you can remember that 1 kilometer is about 1/2 mile. By the same token, 1 kilometer per hour is about 1/2 mile per hour.

This guideline tells you that if you live 2 miles from the nearest supermarket, then you live about 4 kilometers from there. A marathon of 26 miles is about 52 kilometers. And if you run on a treadmill at 6 miles per hour, then you can run at about 12 kilometers per hour. By the same token, a 10 kilometer race is about 5 miles. If the Tour de France is about 4,000 kilometers, then it’s about 2,000 miles. And if light travels about 300,000 kilometers per second, then it travels about 150,000 miles per second.

## Estimate volume

**Here’s how to convert liters to gallons:**1 liter is approximately equal to 0.26 gallons. A good estimate here is that 1 liter is about 1 quart (that is, there are about 4 liters to the gallon).

Using this estimate, a gallon of milk is 4 quarts, so it’s about 4 liters. If you put 10 gallons of gasoline in your tank, this is about 40 liters. In the other direction, if you buy a 2-liter bottle of cola, you have about 2 quarts. If you buy an aquarium with a 100-liter capacity, it holds about 25 gallons of water. And if a pool holds 8,000 liters of water, it holds about 2,000 gallons.

## Estimate weight

**Here’s how to convert kilograms to pounds:**1 kilogram is approximately equal to 2.20 pounds. For estimating, figure that 1 kilogram is equal to about 2 pounds.

By this estimate, a 5-kilogram bag of potatoes weighs about 10 pounds. If you can bench press 70 kilograms, then you can bench press about 140 pounds. And because a liter of water weighs exactly 1 kilogram, you know that a quart of water weighs about 2 pounds. Similarly, if a baby weighs 8 pounds at birth, he or she weighs about 4 kilograms. If you weigh 150 pounds, then you weigh about 75 kilograms. And if your New Year’s resolution is to lose 20 pounds, then you want to lose about 10 kilograms.

## Estimate temperature

The most common reason for estimating temperature in Celsius is in connection with the weather. The formula for converting from Celsius to Fahrenheit is kind of messy:Instead, use the below handy chart to compare Celsius and Fahrenheit temperatures:

Any temperature below 0°C is cold, and any temperature over 30°C is hot. Most of the time, the temperature falls in this middling range. So now you know that when the temperature is 6°C, you want to wear a coat. When it’s 14°C, you may want a sweater or at least long sleeves. And when it’s 25°C, head for the beach!