← Reference library STUDENT REFERENCE · 17 TOPICS

Conversion tables

Metric and imperial units, temperature, land area, pressure, energy, digital storage and conversion examples.

Mass and volume

From	To
1 kilogram	1000 grams
1 gram	1000 milligrams
1 litre	1000 millilitres
1 litre	0.001 cubic metres
1 millilitre	1 cubic centimetre

Mass and volume are different quantities. A litre is a volume, not a mass; converting between them requires density.

Worked example

750 mL ÷ 1000 = 0.75 L. Meanwhile 2.4 kg × 1000 = 2400 g.

Area

1 m² = 10,000 cm²; 1 hectare = 10,000 m². Square the length conversion factor when converting area.

An area conversion applies the length factor twice. Never use the ordinary length factor alone.

Worked example

3 m² × 100² = 30,000 cm². A 1 m by 1 m square is 100 cm by 100 cm.

Time

1 minute = 60 seconds; 1 hour = 3600 seconds; 1 day = 24 hours.

Use fixed-duration units for exact elapsed-time calculations. A calendar month has no single fixed number of days.

Worked example

1.5 hours × 60 = 90 minutes; 90 × 60 = 5400 seconds.

Temperature

°F = (°C × 9/5) + 32; °C = (°F − 32) × 5/9; K = °C + 273.15.

Celsius and Fahrenheit use different zero points. Temperature intervals and absolute temperatures need different treatment.

Worked example

25°C = 77°F = 298.15 K. A rise of 10°C is a rise of 18°F or 10 K.

Worked example

2.5 metres = 250 centimetres. 2.5 m² = 25,000 cm².

Write the starting value with its unit and choose a conversion factor that cancels that unit.

Worked example

72 km/h × 1000 m/km ÷ 3600 s/h = 20 m/s.

Volume and speed quick table

From	To	Rule
1 m³	1,000,000 cm³	Cube the length factor 100.
1 m³	1000 L	Each litre is 0.001 m³.
1 m/s	3.6 km/h	Multiply by 3.6.
1 km/h	5/18 m/s	Divide by 3.6.

How to choose a conversion factor

Write the source unit, multiply by a ratio of equal quantities with that unit in the denominator, then cancel it. Exact definitions remain exact; measured inputs still limit precision. These tables use international inch, foot, yard and mile and avoirdupois mass unless stated otherwise.

Example: 5 ft × (0.3048 m / 1 ft)=1.524 m. Reverse: 1.524 m ÷ 0.3048=5 ft. Round only the final result.

SI prefixes

Prefix	Symbol	Factor
quetta	Q	10³⁰
ronna	R	10²⁷
yotta	Y	10²⁴
zetta	Z	10²¹
exa	E	10¹⁸
peta	P	10¹⁵
tera	T	10¹²
giga	G	10⁹
mega	M	10⁶
kilo	k	10³
hecto	h	10²
deca	da	10¹
deci	d	10⁻¹
centi	c	10⁻²
milli	m	10⁻³
micro	μ	10⁻⁶
nano	n	10⁻⁹
pico	p	10⁻¹²
femto	f	10⁻¹⁵
atto	a	10⁻¹⁸
zepto	z	10⁻²¹
yocto	y	10⁻²⁴
ronto	r	10⁻²⁷
quecto	q	10⁻³⁰

Symbols are case-sensitive. A megawatt is 10⁹ times a milliwatt. Prefixes apply before powers: 1 cm³=(10⁻² m)³=10⁻⁶ m³.

Length and distance

Unit	Equivalent (exact)
1 km	1000 m
1 m	100 cm = 1000 mm
1 inch	2.54 cm
1 foot	12 inches = 0.3048 m
1 yard	3 ft = 0.9144 m
1 mile	1609.344 m
1 nautical mile	1852 m
1 angstrom	10⁻¹⁰ m
1 astronomical unit	149,597,870,700 m

A nautical mile differs from a land mile. 2 miles=3218.688 m. For 5 ft 6 in, convert to 66 inches, then multiply by 2.54 to obtain 167.64 cm.

Area and land measurements

Unit	Equivalent
1 km²	1,000,000 m²
1 cm²	0.0001 m²
1 square foot	0.09290304 m²
1 square yard	0.83612736 m²
1 hectare	10,000 m²
1 acre	4046.8564224 m² = 43,560 ft²
1 square mile	2.589988110336 km²

Bigha, biswa, kanal and marla can vary by region; specify the local definition. A 20 ft ×30 ft plot is 600 ft²=55.741824 m². Area conversion squares the length factor.

Cubic units, litres and gallons

Unit	Equivalent
1 m³	1000 L
1 dm³	1 L
1 cm³	1 mL
1 cubic inch	16.387064 mL
1 cubic foot	28.316846592 L
1 US liquid gallon	3.785411784 L
1 imperial gallon	4.54609 L
1 US liquid quart	0.946352946 L
1 US fluid ounce	29.5735295625 mL
1 imperial fluid ounce	28.4130625 mL

US liquid and imperial measures differ. Fluid ounces measure volume; ounces of mass measure mass. Household cups and spoons also vary. A 2×1×0.5 m tank holds 1 m³=1000 L at those internal dimensions. Cube length factors for volume.

Mass, density and mass–volume conversion

Unit	Equivalent
1 tonne	1000 kg
1 quintal	100 kg
1 kg	1000 g
1 g	1000 mg
1 mg	1000 μg
1 avoirdupois pound	0.45359237 kg
1 avoirdupois ounce	28.349523125 g
1 troy ounce	31.1034768 g
1 g/cm³	1000 kg/m³

Mass=density×volume. There is no universal litre-to-kilogram factor: 2 L at 0.8 kg/L has mass 1.6 kg. A tonne differs from the US short ton (2000 lb) and imperial long ton (2240 lb).

Speed, acceleration and flow

Conversion	Rule
km/h to m/s	Multiply by 5/18
m/s to km/h	Multiply by 3.6
1 mph	0.44704 m/s
1 knot	1852/3600 m/s
1 L/min	1/60 L/s = 1/60000 m³/s
1 m³/h	1000/60 L/min
1 m/s²	100 cm/s²

12 L/min for 5 minutes transfers 60 L at constant flow. Acceleration cannot be converted into speed without a duration and initial velocity.

Pressure, force, energy and power

Unit	Equivalent
1 N	1 kg·m/s²
1 standard kilogram-force	9.80665 N
1 Pa	1 N/m²
1 bar	100,000 Pa
1 standard atmosphere	101,325 Pa
1 psi	≈6894.757 Pa
1 J	1 N·m
1 thermochemical calorie	4.184 J
1 dietary kilocalorie	4184 J
1 Wh	3600 J
1 kWh	3,600,000 J
1 mechanical horsepower	≈745.700 W
1 metric horsepower	735.49875 W

Power is energy per time. Multiply power by duration for energy: 2 kW for 3 hours is 6 kWh.

Angles, time and frequency

Unit	Equivalent
1 full turn	360° = 2π rad
1 degree	π/180 rad
1 angular minute	1/60 degree
1 angular second	1/3600 degree
1 minute of time	60 s
1 hour	3600 s
1 day as duration	86,400 s
1 week	7 days
1 Hz	1 cycle/s
60 revolutions/min	1 revolution/s; angular speed 2π rad/s

Calendar months vary. Gregorian years divisible by 4 are leap years except century years unless divisible by 400. Thus 2000 was a leap year and 1900 was not.

Digital storage and data rate

Unit	Equivalent
1 byte (B)	8 bits (b)
1 kB	1000 B
1 MB	1,000,000 B
1 GB	1,000,000,000 B
1 KiB	1024 B
1 MiB	1,048,576 B
1 GiB	1,073,741,824 B
1 Mbps	1,000,000 bits/s

Mbps means megabits per second, not megabytes. An ideal 80 Mbps is 10 MB/s: 100 MB takes 10 seconds without overhead. Decimal and binary prefixes differ.

Practice with answers

Convert 3 m² to cm².

3×100²=30,000 cm².

Convert 500 cm³ to litres.

500 mL=0.5 L.

Convert 98.6°F to Celsius.

(98.6−32)×5/9=37°C.

A rise of 20°C equals which intervals?

20 K or 36°F. Do not add offsets.

500 W for 4 hours: energy?

2 kWh=7.2 MJ.

10 MiB in bytes?

10,485,760 bytes.

Questions about this guide

How should I use this reference?

Choose a topic, read the rule and its conditions, then solve the worked example yourself. Use the practice questions to check understanding. The search box filters topic sections; clear it to restore the complete guide.

What does this guide cover?

This is a broad school and competitive-exam foundation reference. It includes the topics listed here, but no single page covers every advanced topic or every examination syllabus. Follow the requirements of your course for specialised material.

Can I use it offline or print it?

The guide content is included in this website. Use Print guide and choose your printer or Save as PDF. The print view includes the full guide and practice answers. External reference links are optional further reading.

Sources and further reading

Original explanations and examples prepared for this website. The following educational and standards resources support further checking; the lessons above can be read without opening them.