Reference Chart

Metric Conversion Chart

Q: How do you convert kilometers to miles?

Multiply kilometers by 0.6214 to get miles. Or divide kilometers by 1.609. Quick mental math: kilometers x 0.6 gives you a rough answer (e.g., 10 km is about 6 miles, exact: 6.21 miles). 100 km/h = 62 mph.

Q: How do you convert Celsius to Fahrenheit?

Multiply Celsius by 1.8 (or 9/5), then add 32. So 20°C = (20 × 1.8) + 32 = 68°F. Reverse: subtract 32 from Fahrenheit, then multiply by 5/9. Quick mental: double Celsius and add 30 for a rough Fahrenheit (e.g., 20°C → 70°F approx, exact 68°F).

Q: How many grams in a pound?

1 pound = 453.59 grams (often rounded to 454 g or 450 g). 1 kg = 2.205 lb (often rounded to 2.2 lb). To convert pounds to kilograms quickly, divide by 2.2.

Q: How many milliliters in a cup?

1 US cup = 236.6 milliliters (often rounded to 240 mL). 1 metric cup (used in some countries) = 250 mL exactly. 1 fluid ounce = 29.6 mL.

Q: How many feet in a meter?

1 meter = 3.281 feet, or 3 feet 3.37 inches. Equivalently, 1 foot = 0.3048 meters exactly. To convert meters to feet roughly, multiply by 3.3.

Q: How many liters in a gallon?

1 US gallon = 3.785 liters. 1 UK (Imperial) gallon = 4.546 liters. Always confirm which gallon you mean for non-US conversions; the difference is about 20%.

Q: Is metric or imperial more accurate?

Neither is more accurate; they're both arbitrary scales. Metric is easier to work with because of the decimal/base-10 relationships between units (1 km = 1000 m, 1 m = 100 cm, etc.). Imperial uses irregular conversions (12 in = 1 ft, 3 ft = 1 yd, 5280 ft = 1 mile) that require more memorization.

Q: Why doesn't the US use metric?

The US officially adopted the metric system in 1975 (Metric Conversion Act), but adoption was voluntary. Industries already standardized on imperial resisted change, and Congress declined to mandate conversion. Today, US science, medicine, and the military all use metric internally, but everyday commerce remains imperial.

Q: What is 100 km in mph?

100 km/h equals 62.14 mph. Common European highway speed limits of 100 km/h are roughly equivalent to 60 mph US highway speeds. 130 km/h (German autobahn) = 81 mph.

Q: How do you convert kilograms to pounds?

Multiply kilograms by 2.2046 to get pounds. For quick math, multiply by 2.2. So 70 kg × 2.2 = 154 lb (exact: 154.3 lb). Reverse: pounds × 0.4536 = kg, or just divide pounds by 2.2.

The full reference: every common metric-to-imperial conversion in one chart. Length (millimeters to miles), weight (grams to tons), volume (milliliters to gallons), area (square meters to acres), and temperature (Celsius to Fahrenheit). With exact conversion factors, common shortcuts, and the math behind each conversion.

Length Conversion Chart

From	To	Multiply by	Example
Millimeters (mm)	Inches	0.0394	25.4 mm = 1 in
Centimeters (cm)	Inches	0.3937	2.54 cm = 1 in
Meters (m)	Feet	3.2808	1 m = 3.28 ft
Meters (m)	Yards	1.0936	1 m = 1.09 yd
Kilometers (km)	Miles	0.6214	1.609 km = 1 mi
Inches	Centimeters	2.54	1 in = 2.54 cm
Feet	Meters	0.3048	1 ft = 0.305 m
Yards	Meters	0.9144	1 yd = 0.914 m
Miles	Kilometers	1.6093	1 mi = 1.61 km

Common Length Conversions

Metric	Imperial
1 cm	0.39 in
10 cm	3.94 in
30 cm	11.81 in (about 1 ft)
50 cm	19.69 in
1 m	3.28 ft / 1.09 yd
5 m	16.4 ft
10 m	32.8 ft
100 m	328 ft / 109 yd
1 km	0.62 mi / 1094 yd
5 km	3.11 mi
10 km	6.21 mi
42.2 km (marathon)	26.2 mi
100 km	62.14 mi

Weight / Mass Conversion Chart

From	To	Multiply by	Example
Milligrams (mg)	Grains	0.0154	64.8 mg = 1 grain
Grams (g)	Ounces	0.0353	28.35 g = 1 oz
Kilograms (kg)	Pounds	2.2046	1 kg = 2.20 lb
Kilograms (kg)	Stones (UK)	0.1575	6.35 kg = 1 stone
Metric tons (t)	US tons	1.1023	1 t = 1.10 US tons
Ounces	Grams	28.3495	1 oz = 28.35 g
Pounds	Kilograms	0.4536	1 lb = 0.454 kg
Stones	Kilograms	6.3503	1 stone = 6.35 kg
US tons	Metric tons	0.9072	1 US ton = 0.91 t

Common Weight Conversions

Metric	Imperial
100 g	3.53 oz
250 g	8.82 oz / 0.55 lb
500 g	17.64 oz / 1.10 lb
1 kg	2.20 lb
5 kg	11.02 lb
10 kg	22.05 lb
50 kg	110 lb / 7.87 stone
70 kg	154 lb / 11 stone
100 kg	220 lb / 15.7 stone
1000 kg (1 t)	2,205 lb / 1.10 US tons

Volume Conversion Chart

US measurements unless noted. UK (Imperial) gallons and ounces differ from US measurements.

From	To	Multiply by	Example
Milliliters (mL)	Teaspoons	0.2029	4.93 mL = 1 tsp
Milliliters (mL)	Tablespoons	0.0676	14.79 mL = 1 tbsp
Milliliters (mL)	US fl oz	0.0338	29.57 mL = 1 fl oz
Milliliters (mL)	US cups	0.00423	236.6 mL = 1 cup
Liters (L)	US fl oz	33.81	1 L = 33.8 fl oz
Liters (L)	US gallons	0.2642	3.785 L = 1 US gal
Liters (L)	UK gallons	0.2200	4.546 L = 1 UK gal
Liters (L)	US quarts	1.0567	0.946 L = 1 US qt
Liters (L)	US pints	2.1134	0.473 L = 1 US pt

Cooking Volume Conversions

Measurement	Metric (mL)	US
1 teaspoon	4.93 mL	1/3 tbsp / 1/6 fl oz
1 tablespoon	14.79 mL	3 tsp / 1/2 fl oz
1 fluid ounce	29.57 mL	2 tbsp / 6 tsp
1/4 cup	59 mL	4 tbsp / 2 fl oz
1/3 cup	79 mL	5 tbsp + 1 tsp
1/2 cup	118 mL	8 tbsp / 4 fl oz
1 cup	237 mL	16 tbsp / 8 fl oz
1 pint (US)	473 mL	2 cups / 16 fl oz
1 quart (US)	946 mL	4 cups / 32 fl oz
1 gallon (US)	3,785 mL / 3.785 L	16 cups / 128 fl oz

Area Conversion Chart

From	To	Multiply by	Example
Square cm	Square inches	0.1550	6.45 sq cm = 1 sq in
Square meters (m²)	Square feet	10.764	1 m² = 10.76 sq ft
Square meters (m²)	Square yards	1.1960	1 m² = 1.20 sq yd
Hectares (ha)	Acres	2.4711	1 ha = 2.47 acres
Square kilometers	Square miles	0.3861	2.59 sq km = 1 sq mi
Square feet	Square meters	0.0929	10.76 sq ft = 1 m²
Acres	Hectares	0.4047	2.47 acres = 1 ha
Square miles	Square kilometers	2.5900	1 sq mi = 2.59 sq km

Quick reference: 1 acre = 43,560 sq ft = 4,047 sq m = 0.4047 hectares. A football field (American, excluding end zones) is about 1.1 acres.

Temperature Conversion Chart

Celsius and Fahrenheit don't have a simple multiplier because their zero points differ.

Formulas

Celsius to Fahrenheit: °F = (°C × 9/5) + 32 — or °F = (°C × 1.8) + 32

Fahrenheit to Celsius: °C = (°F − 32) × 5/9 — or °C = (°F − 32) / 1.8

Quick approximation: °F ≈ (°C × 2) + 30, or °C ≈ (°F − 30) / 2. Off by a few degrees but close enough for casual use.

Celsius	Fahrenheit	Context
-40°C	-40°F	Where scales cross (only matching point)
-20°C	-4°F	Severe cold
-10°C	14°F	Bitter cold winter day
0°C	32°F	Water freezes
10°C	50°F	Cool spring day
15°C	59°F	Mild day
20°C	68°F	Room temperature (mild)
25°C	77°F	Warm summer day
30°C	86°F	Hot summer day
35°C	95°F	Very hot
37°C	98.6°F	Human body temperature
40°C	104°F	Heatwave / fever
50°C	122°F	Death Valley summer extreme
100°C	212°F	Water boils (sea level)
180°C	356°F	Common baking temperature
200°C	392°F	Pizza oven / hot baking
220°C	425°F	Roasting temp

Speed Conversion Chart

km/h	mph	m/s	knots	Context
5	3.1	1.4	2.7	Walking pace
10	6.2	2.8	5.4	Brisk walk / jog
15	9.3	4.2	8.1	Easy bike pace
30	18.6	8.3	16.2	City driving / bike race
50	31.1	13.9	27.0	City speed limit (EU)
60	37.3	16.7	32.4	Residential / city driving
80	49.7	22.2	43.2	Suburban driving
100	62.1	27.8	54.0	EU motorway / US highway
120	74.6	33.3	64.8	EU highway top
130	80.8	36.1	70.1	French highway limit
160	99.4	44.4	86.4	German autobahn cruise
200	124.3	55.6	108.0	Highway-cruising sports cars

Quick conversions: km/h × 0.62 = mph. mph × 1.61 = km/h. m/s × 3.6 = km/h. m/s × 2.24 = mph.

Metric System Guide

Why Metric Works So Well

The metric system uses powers of 10 for all conversions within a unit type. 1 meter = 100 centimeters = 1,000 millimeters. 1 kilogram = 1,000 grams. 1 liter = 1,000 milliliters. This means converting between units is just moving the decimal point, with no awkward multiplication or memorization.

Imperial uses irregular conversions: 12 inches per foot, 3 feet per yard, 5280 feet per mile. 16 ounces per pound. 8 fluid ounces per cup, 2 cups per pint, 2 pints per quart, 4 quarts per gallon. These all need to be memorized.

Metric Prefixes

Prefix	Symbol	Multiplier
Tera	T	1,000,000,000,000 (10¹²)
Giga	G	1,000,000,000 (10⁹)
Mega	M	1,000,000 (10⁶)
Kilo	k	1,000 (10³)
Hecto	h	100 (10²)
Deca	da	10 (10¹)
(base unit)	—	1 (10⁰)
Deci	d	0.1 (10⁻¹)
Centi	c	0.01 (10⁻²)
Milli	m	0.001 (10⁻³)
Micro	µ	0.000001 (10⁻⁶)
Nano	n	0.000000001 (10⁻⁹)

Mental Math Shortcuts

km to miles: multiply by 0.6 (e.g., 50 km ≈ 30 mi; exact 31 mi)
miles to km: multiply by 1.6 (e.g., 60 mi ≈ 96 km; exact 97 km)
kg to lb: multiply by 2 then add 10% (e.g., 70 kg = 140 + 14 = 154 lb)
lb to kg: divide by 2 then subtract 10% (e.g., 200 lb / 2 = 100, minus 10% = 91 kg)
°C to °F: double, add 30 (e.g., 25°C × 2 + 30 = 80°F; exact 77°F)
°F to °C: subtract 30, halve (e.g., (80 − 30) / 2 = 25°C; exact 27°C)
L to gal: divide by 4 (close to 3.785; e.g., 40 L ≈ 10 gal; exact 10.6 gal)
cm to in: divide by 2.5 (e.g., 100 cm / 2.5 = 40 in; exact 39.4 in)

Countries That Use Imperial

Only three countries primarily use imperial measurements: the United States, Liberia, and Myanmar. Every other country uses metric officially. The UK, Canada, and Australia use a mix: metric for most official and scientific work, with some traditional imperial holdouts (UK pints in pubs, road distances in miles, body weight in stone; Canadian temperatures in Celsius but recipes sometimes in cups).

When Imperial Sneaks Back In

Even in fully-metric countries, some imperial vestiges remain:

TV and computer screen sizes worldwide are in inches
Wheel and tire sizes worldwide are partly in inches (the wheel diameter)
Pipe and fitting threads use imperial sizes globally (NPT, BSP both reference inch dimensions)
Aviation uses feet (altitude) and knots (speed) globally
Marine navigation uses nautical miles and knots globally
Pixels per inch (PPI) and dots per inch (DPI) for screens and printing remain imperial

Frequently Asked Questions

How do you convert kilometers to miles?

Multiply km by 0.6214, or divide by 1.609. Quick: km × 0.6 gives a close approximation.

How do you convert Celsius to Fahrenheit?

°F = (°C × 1.8) + 32. Quick: double Celsius, add 30 for rough answer.

How many grams in a pound?

1 lb = 453.59 g (~454 g). 1 kg = 2.205 lb.

How many milliliters in a cup?

1 US cup = 236.6 mL (~240 mL). 1 metric cup (some countries) = 250 mL. 1 fl oz = 29.6 mL.

How many feet in a meter?

1 m = 3.281 ft, or 3 ft 3.37 in. 1 ft = 0.3048 m exactly.

How many liters in a gallon?

1 US gal = 3.785 L. 1 UK (Imperial) gal = 4.546 L. Always confirm which gallon.

Is metric or imperial more accurate?

Neither. Metric is easier because of decimal/base-10 relationships. Imperial requires more memorization.

Why doesn't the US use metric?

The US adopted metric in 1975 voluntarily. Industries had standardized on imperial and resisted. Science, medicine, and military use metric internally.

What is 100 km in mph?

100 km/h = 62.14 mph. European 100 km/h limits roughly match US 60 mph.

How do you convert kilograms to pounds?

Multiply kg by 2.2046 (or 2.2 for quick math). 70 kg × 2.2 = 154 lb.

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We built this because most metric conversion charts cover only the top three or four conversions and leave out the units you actually need (square kilometers? cubic feet? milliliters to teaspoons?). This page covers everything you'd reach for. This site is a part of the ads4good Network.