Metric yardstick

This article gives some rough rules of thumb for comprehending the metric system in terms of everyday life.

Metric yardsticks based on everyday objects

Length

• One meter equals roughly one (longish) step of a tall adult man. Two cubits as perceived by such a person may come to about one meter.
• The length of a one-second pendulum is approximately one meter.
• One kilometer equals ten minutes' walk.
• The distance between nails of fingers pressed together is roughly 1 cm or 10 mm.
• the width of a fingernail is roughly 1 cm.
• The cubit arm (forearm from elbow to fingertips) is roughly 50 cm. This is known as metric cubit and has been used in some countries.
• The width of man's hand is about one decimeter or 10 cm. That is almost the same as the old English unit "hand".
• The side of a matchbox is 5 cm.

Area

• A large soccer field has an area of one hectare (10,000 square meters).
• The area covered by a large umbrella is roughly one square meter.

Volume

• A cube of one hand (1 decimeter) per side is equal to one liter.
• A drop of water (or water-based solution, like milk, tears, etc.) is very close to 0.05 milliliters. 20 drops make one milliliter. This is an approximation used in chemical engineering. One liter is therefore roughly 20,000 drops.
• Both the British and American pints are close to 1/2 L, sometimes called the "metric pint".
• Soft drinks are sold in 1, 1.5, 2 and 3 liter bottles.

Cooks beware - Cup sizes differ widely.

Nation	Standard cooking cup
Japan	180 ml
USA	237 ml?
Australia	250 ml

Mass

• One millilitre (1 ml) of water is one gram (1 g), and therefore 1000 millilitres of water (1 l) is 1 kilogram (kg).
• One litre (1 l) of water is one kilogram (1 kg), and therefore 1000 liters of water (a cubic meter - 1 m³) is 1 tonne.
• One tonne (1 t = 1000 kg) is roughly the mass of an economy motor car.
• One U.S. "nickel" (5 cent coin) has a mass of 5 g.
• One litre of a soft drink has a mass of roughly 1 kg.

Force

• A small apple on Earth exerts a force due to gravity of about one newton (N). (Remember Newton's apple)
• One kilogram at the Earth's surface exerts a force due to gravity very close to 10 N.
• One newton-meter torque is roughly the increase in torque by adding a small apple to the end of an outstretched walking stick.

Temperature

• For Celsius temperatures
  • 30 is hot
  • 20 is nice
  • 10 is chilly
  • 0 is ice.
• Normal room temperature is roughly 22 °C
• An outside temperature of 300 kelvins (273 + 27 °C) means bikini weather.
• The USMA (United States Metrication Association) romotes the following jingle to spread awareness of Celsius: "0 is cold, 10 is not, 20 is warm, and 30 is hot"

Pressure

• Normal air pressure at sea-level is around 100 kilopascals. It equals approximately 1 kgf/cm²
• Every ten metres' depth of seawater exerts about one bar or 100 kPa or 1 kg/cm^{2 of additional pressure.}

Conversion hints

For users of the English system there are a few simple equivalents and conversion factors that help in learning to be comfortable with the metric system:

Near equivalents

The following units are the same within a few percent. The slightly larger unit is listed first

• 1 meter ≈ 1 yard
• 1 liter ≈ 1 quart
• 1 long ton ≈ 1 metric tonne
• 1 BTU ≈ 1 kilojoule

Approximate conversion factors

Length

• 1 nautical mile ≈ 1852 m
• 1 mile ≈ 1.6 km
• 1 meter ≈ 1.1 yard ≈ 3.28 ft
• 1 yard ≈ 0.9 meters
• 1 foot ≈ .3048 m, very roughly 1/3 of a meter; 10 ft ≈ 3.048 m
• 1 inch ≈ 25 mm, 4 inches ≈ 10 cm

Surface

• 1 acre ≈ 4000 square meters ≈ 0.4 hectare

Mass

• 1 kilogram ≈ 2.2 lb
• 1 ounce ≈ 28 grams
• 2 pounds ≈ 1 kg: 2 lb ≈ 900 grams

Volume

• 1 US cup ≈ 240 ml
• 1 teaspoon = 5 ml

Celsius landmarks

The table below lists easy to remember or particularly important Celsius temperatures.

°C	°F	Landmark
-273	–459.67	Absolute zero (zero kelvins).
-40	-40	Numeric conversion exact.
-11.4	+11.4
0	32	Freezing point of pure water. Numeric conversion exact.
4	40	Temperature of water's triple-point, and point of maximum density of water in liquid form. Also temperature of domestic refrigerators.
10	50	Numeric conversion exact.
16	61	Numeric conversion exact.
22	72	Room temperature
28	82	Numeric conversion exact.
30	86	Beach weather. Numeric conversion exact.
37	98.6	Human Body temperature. Numeric conversion exact
37.5	100	The ton. Old mark for a hot day in Australia. Uncomfortable.
40	104	Hot tub. Numeric conversion exact. Feverish baby - time to get help.
100	212	Numeric conversion exact. Boiling point of pure water.

See also

• Metrication
• Approximate conversion of units

External links

• Unit converter