Metric versus U.S. units

This page provides information about units used in Switzerland - which are the same as in most other European countries - and how they relate to the U.S. unit system. The content is divided into four sections as laid out in the table of contents.

Table of contents:

1. General information about the metric unit system:

The metric unit system is easy to handle because everything is a multiple or a fraction of ten. There is a base unit for each type of measurement, such as meter (abbreviation m) for length, gramm (abbreviation g or gr) for weight or liter (abbreviation l or lt) for volume.

Ten base units have the prefix deka (which is however rarely used), for example 1 dekameter (Dm) equals to 10 meters.
Hundred base units have the prefix hekto, for example 1 hektoliter (hl) equals to 100 liters.
One thousand base units have the prefix kilo, for example 1 kilogramm (kg) equals to 1'000 gramms.
After that, the naming schema applies in steps of the factor 1000, such as mega for 1'000'000 base units, giga for 1'000'000'000 base units and so on. In order to keep the numbers short and easier to read, a so called scientific notation is often used, like 1E6 for 1'000'000 or 3E9 for 3'000'000'000. xEn is a short form of x times 10 power n (x*10^n).

A very similar schema applies for fractions of the base units. A tenth of the base unit has the prefix deci, for example 1 deciliter (dl) equals to 0.1 liter.
A hundredth of the base unit has the prefix centi, for example 1 centimeter (cm) equals to 0.01 meter.
One thousandth of the base unit has the prefix milli, for example 1 millimeter (mm) equals to 0.001 meter.
After that, the naming schema applies in steps of the factor 0.001, such as mikro for 0.000'001 base units, nano for 0.000'000'001 base units and so on. Again, there is a scientific notation for small numbers such as 1E-6 for 0.000'001.

The tables below shows the names for multiples and fractions of the base unit:

fractions
number	scientific notation	name	abbreviation
0.1	1E-1	deci	d
0.01	1E-2	centi	c
0.001	1E-3	milli	m
0.000'001	1E-6	mikro	µ
0.000'000'001	1E-9	nano	n
0.000'000'000'001	1E-12	pico	p
0.000'000'000'000'001	1E-15	femto	f
0.000'000'000'000'000'001	1E-18	atto	a

There is also a special unit for length called angström, which is 1E-10 of a meter, the order of magnitude of the size of an atom.

multiples
number	scientific notation	name	abbreviation
10	1E1	deka	D
100	1E2	hekto	h
1'000	1E3	kilo	k
1'000'000	1E6	mega	M
1'000'000'000	1E9	giga	G
1'000'000'000'000	1E12	tera	T
1'000'000'000'000'000	1E15	peta	P
1'000'000'000'000'000'000	1E18	exa	E

2. Metric to U.S. units conversion:

Dimensions:

Metric unit	U.S. unit	Metric unit	U.S. unit	Metric unit	U.S. unit
Length		Area		Volume
1 mm	0.03937 inches	1 mm²	0.001550 sq. inches	1 ml	0.03381 fl. ounces
1 cm	0.3937 inches	1 cm²	0.1550 sq. inches	1 l	2.113 pints 1.056 quarts 0.2641 gallons
1 m	3.281 feet 1.094 yards	1 m²	10.76 sq. feet 1.196 sq. yards
1 km	0.6214 miles	1 km²	247.1 acres 0.3861 sq. miles

Weight:

Metric unit	U.S. unit
1 gr	0.03527 ounces
1 kg	35.27 ounces 2.205 pounds
1 t	2'205 pounds 1.102 tons

Temperature:

Celsius	Fahrenheit
-17.78	0.0
0	32
10	50
20	68
30	86
50	122
100	212

3. General information about the U.S. unit system from an European point of view:

From an European point of view, the U.S. unit system seems quite complicated and impractical. The difficulty comes mainly from the fact, that larger units seem to be an arbitrary multiple of the next smaller unit. For example, 3 feet equal to 1 yard, 1 foot equals to 12 inches, so 1 yard equals to 36 inches. The same is true for volume, where 1 gallon equals to 4 quarts, 8 pints, 16 cups, 256 tablespoons or 768 teaspoons.

Interestingly, there are some areas, where U.S. units are very common in Europe anyway. For example, plumbers use inches to measure the diameter of their tubes and also the dimensions of tires for cars and bikes are always specified in inches.

On the other hand, the U.S. government has decided to switch to the metric unit system during the next few years. For example, the national park service (NPS) has already switched to the metric unit system, all their more recent brochures and signs use metric units as the leading unit system and only mention the U.S. units for reference.

4. U.S. to metric units conversion:

Dimensions:

U.S. unit	Metric unit	U.S. unit	Metric unit	U.S. unit	Metric unit
Length		Area		Volume
1 inch	25.4 mm	1 sq. inch	645.16 mm² 6.4516 cm²	1 teaspoon	4.929 ml
1 foot	30.48 cm	1 sq. foot	929.0 cm² 9.290 dm²	1 tablespoon	14.79 ml
1 yard	91.44 cm 0.9144 m	1 sq. yard	0.8361 m²	1 fl. ounce	29.57 ml
1 mile	1.609 km	1 acre	4'046 m²	1 cup	0.2365 l
1 nautical mile	1.852 km	1 sq. mile	2.590 km²	1 pint	0.4732 l
				1 quart	0.9464 l
				1 gallon	3.785 l

Weight:

U.S. unit	Metric unit
1 ounce	28.35 gr
1 pound	453.6 gr 0.4536 kg
1 ton	907.2 kg 0.9072 t

Temperature:

Fahrenheit	Celsius
0	-17.78
10	-12.22
20	-6.667
50	10
80	26.67
100	37.78

Metric versus U.S. units and unit conversion tables

Table of contents:

1. General information about the metric unit system:

The tables below shows the names for multiples and fractions of the base unit:

2. Metric to U.S. units conversion:

Dimensions:

Weight:

Temperature:

3. General information about the U.S. unit system from an European point of view:

4. U.S. to metric units conversion:

Dimensions:

Weight:

Temperature: