The no-nonsense, straightforward answer to “How many liters are in a quart?” is 0.946352946 liters.
Put another way, a bit under 9-and-a-half tenths of a quart, and if that’s too pedantic for you, then “very nearly one quart.”
However, if you try pouring 20 quarts into 20 one-liter bottles, you’ll find yourself with an extra bottle.
On the other hand, if you try pouring 20 liters into 20 one-quart bottles, you’ll no doubt discover that you’re shy of one quart.
Table of Contents
- What is a (US) quart?
- What is a liter?
- Why the liter isn’t – strictly speaking – an SI unit
- Derived SI units
- US customary volume units
- America and SI
- Will America ever really adopt SI?
- America’s customary measuring system vs. SI
- What’s so wonderful about SI anyway?
- America actually uses the metric system every day
- How adopting the metric system can make a huge difference
- Why the International System of Units is abbreviated SI, not IS
- How, for a time, the liter was “too big”
The quart (symbol QT) measures quantity in the United States’ customary and imperial measurement systems, and there are multiple ways to define a quart.
A (US) liquid quart is approximately 0.946353 liters, while a dry quart equals roughly 1.101221 liters. For comparison, in the UK, the imperial liquid quart is equivalent to 1.136523 liters.
For both the UK and the US, the size of a quart is equivalent to ¼ of a gallon.
Quarts are based on gallons, and the meaning of “gallon” has varied throughout time, based on the product being used to define it. The definition for the US quart is based on the English gallon of wine.
The same definition was used to define the imperial quart in 1824 when the UK redefined the size of a gallon to the imperial gallon.
Variants of the quart have been utilized predominantly within both the United States and the United Kingdom, but in the UK, the use of the liter has become mandatory as a consequence of metrication.
The liter (symbol ‘L’) is a volume measurement unit in the International System of Units (SI). However, it is not strictly an SI unit. One liter equals one thousand cubic centimeters (cm3).
Between 1901 and 1964, a liter was specified as the displacement of 1 kilogram of unadulterated water at maximally dense atmospheric pressure. However, because the mass-volume relation of water is determined by several hard-to-regulate variables (isotopic uniformity, purity, pressure, and temperature) and the fact that the initial definition that was used to define the kilogram had been a bit too big (see below), in 1964, the definition of liter was modified to reflect its original and the current definition.
We use liters to quantify many liquid volumes and identify containers that store those liquids. It can also quantify non-liquid volumes, like the size of backpacks, trunks for cars and climbing bags, computer cases, microwaves, refrigerators, and recycling bins, and express fuel volumes and prices in most countries in the world.
If you look on the web to see why the liter isn’t technically an SI unit, the standard, often repeated answer you’ll get is, “Because liter is a derived unit.” That’s all very well, but what does that actually mean?
A derived unit is a unit that is “worked out” from other primary units. So, for example, a liter is the volume enclosed by a container that is 10 cm (centimeters) wide, 10 cm long, and 10 cm tall.
Doing the calculation for volume, breadth x length x height, we get 10 x 10 x 10, which is 1,000, so a liter is 1,000 cm3.
Now, if you know your SI units, you’ll recognize 1,000 cm3 as a cubic decimeter (dm3). Now, you might be asking yourself, “What the heck is the difference?” The answer is actually quite simple.
A decimeter (dm) is 10 centimeters, and that’s that.
A decimeter is 10 centimeters, so a cubic decimeter is equal to the volume of something that is 1 dm wide, 1 dm long, and 1 dm tall, which is 1,000 centimeters. In the case of the liter, society has simply decided that it is a volume enclosed by 10 cm on all sides.
Society could just have easily chosen the liter to mean 11 cm wide, 12 cm long, and 13 cm tall, although I’m sure we’re both glad that society didn’t!
The US standard system of measurement is the measurement system that is used widely within the United States. It is called the “customary” or “standard” system within the US.
More formally, it is called the “traditional system of weights and measures.” It was introduced in America by the colonists who came from England and who built their new system on the foundation of units used in England before those were replaced with the imperial system.
Volume refers to capacity. For instance, the size of the space within a bowl or the amount of water it would take to fill a bath. In the US standard measure, the most commonly used volumes are gallons (gal) and quarts (qt), pints (pt), cups (C), tablespoons (T), and teaspoons (t).
1 gallon contains 4 quarts, which contains 8 pints, which contains 16 cups, which contains 256 tablespoons, which contains 768 teaspoons.
The US also uses fluid ounces (fl. oz.) to measure volume, like this:
- 1 fl. oz. = 2 tablespoons
- 8 fl. oz. = 1 cup
- 16 fl. oz. = 1 pint
- 32 fl. oz. = 1 quart
There are three countries that don’t use SI: Burma (aka Myanmar), Liberia, and the United States. Only these three countries don’t use the International System of Units (SI), which is often called “the metric system.”
However, it’s important to note that although the metric system isn’t standard in the U.S., it does still use the metric system in certain situations.
The metric system is used in the sciences and, slowly, it is being adopted in other areas as well. In fact, every economy worldwide is situated in a continuum that is moving towards increased SI usage.
Some countries have changed their laws to implement an obligatory metric policy, while others have opted for a voluntary metrication process.
The United States was one of the first nations to sign the Treaty of the Meter in 1875. So, legally, Americans have been allowed to use SI units since 1866, and it was adopted as the primary method of measurement and weight in US trade and commerce in 1988. Households and individuals, however, still primarily use the imperial system.
It is likely that the United States will never fully use the metric system, even though the system is much more understandable and most of the world utilizes it. Why?
Simply put, it will require too much time and money.
The debate about switching units came up in Congress in 1975. However, the adoption of a bill that favored a metric-based system was stymied by large corporations and American citizens who did not want to endure the lengthy and costly process of altering the country’s whole infrastructure.
Many people thought it important that the United States kept its unique system of government that distinguished it from other countries and represented its position as a leader of other nations instead of a follower.
Most countries employ the metric system, which utilizes units of measurement like grams and meters. It also includes prefixes like ‘centi’ (e.g., centiliter), ‘kilo’ (e.g., kilogram), and ‘milli’ (e.g., millimeter) to count in orders of magnitude.
In the United States, we use the more traditional imperial system, in which everything is measured by inches, feet, and pounds. Our system’s split is based on many reasons, but the main arguments regarding the creation of an appropriate national standard for measurement can be traced back to 1790.
The metric system is based on the number 10 as a measurement. This permits conversions between different units to be made more easily by shifting a decimal point to the left or the right.
Humans find it much easier to count in tens than in any other number because all we have to do is add or remove zeros.
The U.S. customary system is based on the imperial system, which is considerably less flexible. The numbers can vary a lot since there is no standard for each measurement.
It’s not possible to ignore the SI system in the United States. The SI defines all the measurement units that we use, including US customary units you’re familiar with (Fahrenheit, gallons, pounds, and feet).
Measurements in metric units have defined volume, length, and mass since 1893! The impact of SI is all-encompassing and pervasive, even though most people aren’t aware of it.
While US customary units are still used alongside the metric units on labels for products and product literature, it is not uncommon for items to be produced with SI-based manufacturing techniques. Why? Although some companies are worried that customers expect customized units on packaging in the case of manufacturing processes, they’re under constant pressure to keep their businesses ahead of the curve.
Implementing the latest scientific and technological advances is a lot easier when using the same units of measurement as the rest of the global community.
During the 2008 recession and its aftermath, lumber companies in the US Northwest lost market share to their Canadian and Japanese competitors, who both use the metric system. The producers of wood products then made changes to ensure that their production processes could adapt to metric and US customary systems based on the requirements of their customers.
Since most of the world’s population uses only the metric system, US companies are increasingly recognizing the advantages of SI as they seek out new markets.
Why the International System of Units is abbreviated SI, not IS
“SI” is an acronym of Systeme international, an abbreviated version of the original French title Systeme international d’unites, literally translating to “International System of Units.” Through a CGPM (General Conference on Weights and Measures) 1960 resolution, the international abbreviation is SI, in recognition of the French origins of the organization.
How, for a time, the liter was “too big”
Between 1901 and 1964, the kilogram equaled the mass of a cylinder made of iridium and platinum called the International Prototype of the Kilogram. The term ‘liter’ was defined by the amount of pure water at its highest volume of 4° Celsius at standard atmospheric pressure displaced by one kilogram.
However, it was later realized that the definition of the kilogram was approximately 28 parts for every million, which meant that every liter was actually 1.000028 dm3 in volume!