  # Kilogram vs. Kilo — What's the Difference?

Kilogram (kg) is a unit of mass in the metric system, equal to 1,000 grams. "Kilo" is a prefix meaning "one thousand" but often colloquially used to refer to a kilogram. ## Key Differences

The term "kilogram" is a specific measurement of mass in the International System of Units (SI). It is the only base unit with a prefix ("kilo-") in its name. The kilogram is used in science, engineering, and commerce worldwide. It's defined by the mass of a physical prototype, which is kept at the International Bureau of Weights and Measures.
"Kilo" is a standalone prefix in the metric system denoting a factor of one thousand, or
. While it is commonly used to refer to a kilogram, it can be applied to any metric unit to indicate a thousandfold of that unit. For instance, "kilometer" means one thousand meters.
The kilogram is often the default unit of weight when the metric system is used. It's fundamental for trades and scientific research where precise measurements of mass are indispensable. The standard abbreviation for kilogram is "kg," and this specificity is critical for maintaining consistency in technical fields.
The usage of "kilo" can be less formal and may not always refer to mass. It can be used in various contexts, such as kilojoule (a unit of energy) or kiloliter (a unit of volume). Despite its versatility, when "kilo" is used alone, it is generally understood to be shorthand for a kilogram.
In summary, a kilogram is an SI unit of mass, precisely defined and regulated by international agreement. "Kilo" is a prefix that means one thousand but is often informally used to mean a kilogram. The distinction is important in technical and scientific communication to prevent ambiguity.

## Comparison Chart

### Definition

A unit of mass equal to 1,000 grams.
A metric prefix meaning one thousand.

### Usage

Specifically refers to mass.
Can refer to any metric unit (e.g., kilometer, kilowatt).

### Formality

Used in formal and scientific contexts.
Used both formally for units and informally for kilograms.

### Abbreviation

Abbreviated as "kg".
No standalone abbreviation; modifies unit (e.g., "km" for kilometer).

### Measurement

Represents a concrete measurement.
Represents a numerical multiplier.

## Compare with Definitions

#### Kilogram

A metric unit of mass equal to 1,000 grams.
The bag of rice weighs one kilogram.

#### Kilo

Colloquial for a kilogram, especially in reference to groceries or produce.
He added a kilo of sugar to his shopping cart.

#### Kilogram

A standard of mass upon which other weights are calibrated.
The scale was calibrated using a standard one-kilogram mass.

#### Kilo

Informally used to reference a thousand pieces or units of a given item.
They ordered a kilo of bananas.

#### Kilogram

The base unit of mass in the International System of Units (SI).
A kilogram is equal to the mass of the international prototype of the kilogram.

#### Kilo

Slang for kilogram, often used in the context of illicit drugs.
The dealer was caught with a kilo of contraband.

#### Kilogram

A mass measurement commonly used in commerce and everyday life.
The newborn baby weighed just under three kilograms.

#### Kilo

A common abbreviation for a kilogram, primarily used in speech.
I lost four kilos this month.

#### Kilogram

A unit used for measuring mass in scientific contexts worldwide.
She needs a two-kilogram weight for her physics experiment.

#### Kilo

A prefix denoting one thousand units in the metric system.
The marathon is 42 kilos long.

#### Kilogram

The kilogram (also kilogramme) is the base unit of mass in the International System of Units (SI), the metric system, having the unit symbol kg. It is a widely used measure in science, engineering and commerce worldwide, and is often simply called a kilo in everyday speech.

A kilogram.

#### Kilogram

Abbr. kg The base unit of mass in the International System, equal to 1,000 grams (2.2046 pounds). See Table at measurement.

#### Kilo

Clipping of kilogram

Kilogram force.

#### Kilo

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#### Kilogram

In the International System of Units, the base unit of mass; conceived of as the mass of one litre of water, but now defined by taking the fixed numerical value of the Planck constant h to be 6.626 070 15 × 10-34 when expressed in units of kg⋅m2⋅s−1. Symbol: kg

#### Kilo

An abbreviation of Kilogram.

#### Kilogram

(proscribed) The unit of weight such that a one-kilogram mass is also a one-kilogram weight.

#### Kilo

One thousand grams; the basic unit of mass adopted under the Systeme International d'Unites;
A kilogram is approximately 2.2 pounds

#### Kilogram

A measure of weight, being a thousand grams, equal to 2.2046226 pounds avoirdupois (15,432.34 grains). It is equal to the weight of a cubic decimeter of distilled water at the temperature of maximum density, or 39° Fahrenheit.

#### Kilogram

One thousand grams; the basic unit of mass adopted under the Systeme International d'Unites;
A kilogram is approximately 2.2 pounds

## Common Curiosities

#### Is "kilo" the same as "kilogram"?

Colloquially, yes; technically, "kilo" is a prefix, while "kilogram" is a unit of mass.

#### Can "kilo" be used to reference things other than mass?

Yes, "kilo" is a prefix for one thousand of any metric unit.

#### What is the symbol for a kilogram?

The symbol for a kilogram is "kg."

#### Is "kilo" ever written out fully?

Not usually; it's most commonly abbreviated as "k" in compound terms.

#### Is "kilo" an official metric unit?

No, "kilo" is a prefix, not a standalone unit.

#### How do you convert pounds to kilograms?

Divide the number of pounds by 2.20462 to get kilograms.

#### How is the mass of one kilogram defined?

It was originally defined by the mass of a liter of water, now by a physical constant.

#### Can "kilo" stand alone in a sentence?

Informally, yes, especially in the context of weight, it's understood to mean kilograms.

#### Why is "kilogram" the only SI unit with a prefix?

Historically, it was kept for convenience to denote a practical unit of mass.

#### Are kilograms used in all countries?

Most countries use kilograms as part of the metric system, except for the U.S., which uses pounds.

#### Can "kilos" be used to express weight?

Informally, yes, but weight is technically a force measured in Newtons.

#### What items are commonly measured in kilograms?

Groceries, body weight, and gym weights are often measured in kilograms.

#### What does "kilo" mean in the context of drugs?

It's slang for a kilogram, referring to the quantity of the substance.

#### Is the kilogram still based on a physical object?

No, since 2019, it's defined by the Planck constant.

#### Do scientists use "kilo" or "kilogram" in papers?

Scientists use "kilogram" for precision and clarity in academic papers.