How many mL equals a gallon of water?

A gallon of water equals 3,785.41 milliliters (mL). This conversion can be helpful when cooking, mixing solutions, or measuring out liquids for other purposes.

Quick Summary

Here is a quick summary of how many mL are in a gallon:

  • 1 gallon = 3,785.41 mL
  • 1 mL = 0.00026417 gallons
  • To convert gallons to mL, multiply gallons by 3,785.41
  • To convert mL to gallons, divide mL by 3,785.41

The Gallon Unit of Measurement

The gallon is a customary unit of measurement for volume in both the US and Imperial measurement systems. Some key facts about the gallon:

  • 1 US gallon = 231 cubic inches = 3.78541 liters
  • 1 Imperial gallon = 277.42 cubic inches = 4.54609 liters
  • The US gallon is smaller than the Imperial gallon
  • Gallons are often used to measure liquids like water, milk, juice, gasoline, etc.

For the purposes of this article, we will be using the US gallon measurement.

Origins of the Gallon Unit

The gallon unit originated in the British Empire. The word “gallon” comes from the Old French word “galon” which meant “jug, bucket.” The gallon was originally defined as the volume occupied by 10 pounds of water at a specific gravity of 1 (at 62 °F). This definition was officially adopted in Great Britain in 1824. Over time the gallon measurement was standardized by the Imperial system and US customary units to the values we know today.

Uses for the Gallon Measurement

The gallon measurement is commonly used:

  • When buying gasoline for cars – gallon is a standard unit at gas stations
  • When purchasing milk, juice, water and other liquids at the grocery store
  • For mixing solutions with precise ratios for cleaning, cooking, chemistry experiments, etc.
  • For measuring water usage for residential water bills
  • In recipes for food and beverages
  • Industrial applications for measuring chemical quantities

The gallon measurement allows for reasonably sized volumes useful for consumer and commercial transactions. It bridges the gap between the very small milliliter measurements and very large measurements like barrels or tanker trucks.

The Milliliter (mL) Metric Unit

The milliliter is a metric unit of volume. Some key facts about the milliliter:

  • 1 milliliter = 1 cubic centimeter (cm3, CC)
  • 1,000 milliliters = 1 liter
  • The milliliter is 1/1,000th of a liter
  • Milliliters are commonly used in medicine and chemistry
  • Milliliters allow for precise measurement of small volumes

Origins of the Milliliter

The milliliter originated when the metric system was introduced in France after the French Revolution. The metric units were designed to relate volumes to the meter length unit. One cubic centimeter of water was originally defined as having a mass of 1 gram. The milliliter was defined as 1/1,000th of a liter – equivalent to 1 cubic centimeter.

Uses for the Milliliter Measurement

Some common uses for the milliliter measurement include:

  • Measuring medicine doses like cough syrup, eye drops, etc.
  • Titrating solutions in chemistry experiments
  • Measuring small amounts of food ingredients for recipes
  • Calibrated laboratory pipettes for accuracy
  • Measuring alcohol for mixed drinks

The small size of the milliliter allows for precise measurement not practical with larger units. Milliliters are popular for scientific and medical applications where accuracy is critical.

Converting Between Gallons and Milliliters

Since gallons and milliliters are different volume units, conversions between the two are often necessary. Here are the key conversion factors between US gallons and milliliters:

  • 1 US gallon = 3,785.41 mL
  • 1 mL = 0.00026417 US gallons

Using these conversion factors, you can calculate mL to gallons or gallons to mL. For example:

Converting 5 gallons to milliliters:
5 gallons x 3,785.41 mL/gallon = 18,927.05 mL

Converting 800 mL to gallons:
800 mL x (1 gallon / 3,785.41 mL) = 0.211338 gallons

Converting Gallons to Milliliters

To convert from gallons to milliliters:

  1. Write down the amount in gallons
  2. Multiply the gallon amount by the conversion factor 3,785.41 mL/gallon


  • 4 gallons x 3,785.41 mL/gallon = 15,141.64 mL
  • 0.5 gallon x 3,785.41 mL/gallon = 1,892.705 mL
  • 1.333 gallons x 3,785.41 mL/gallon = 5,047.2113 mL

Converting Milliliters to Gallons

To convert milliliters to gallons:

  1. Write down the milliliter amount
  2. Multiply by the conversion factor 1 gallon/3,785.41 mL
  3. Or divide the milliliter amount by 3,785.41


  • 8,000 mL x (1 gallon / 3,785.41 mL) = 2.112 gallons
  • 650 mL / 3,785.41 mL/gallon = 0.17175 gallons
  • 55,300 mL / 3,785.41 = 14.601 gallons

Real World Examples

Here are some real world examples of converting between gallons and milliliters:

Mixing a Chemical Solution

A chemistry experiment calls for a 15% sodium chloride (NaCl) solution. You need to mix up 2 gallons of the solution. How many milliliters of sodium chloride would you need?

First convert gallons to milliliters:

2 gallons x 3,785.41 mL/gallon = 7,570.82 mL (total solution volume)

15% of 7,570.82 mL is 1,135.62 mL

So you would need 1,135.62 mL of sodium chloride for a 15% NaCl solution totaling 2 gallons.

Filling Up a Gas Can

You need to fill up a 5 gallon gas container. If gasoline is dispensed at a rate of 0.6 gallons/minute, how many minutes will it take to fill the can?

First convert the gas can volume to milliliters:
5 gallons x 3,785.41 mL/gallon = 18,927.05 mL

Gas dispenses at 0.6 gallons/minute:
0.6 gallons x 3,785.41 mL/gallon = 2,271.246 mL/minute

Divide total volume by dispense rate:

18,927.05 mL / 2,271.246 mL/minute = 8.34 minutes

So at a rate of 0.6 gallons/minute, it will take 8.34 minutes to fill the 5 gallon gas can.

Calculating Water Usage

Your residential water bill shows usage of 7,000 gallons last month. The water rate is $0.005 per gallon. How much was the total bill?

First convert gallons to milliliters:
7,000 gallons x 3,785.41 mL/gallon = 26,497,870 mL

The rate is $0.005 per gallon:

26,497,870 mL x ($0.005 / 3,785.41 mL/gallon) = $350

So the total bill for 7,000 gallons at $0.005/gallon is $350.

Milliliters to Gallons Conversion Table

Here is a conversion table showing some common milliliter values converted to gallons:

Milliliters Gallons
100 mL 0.026417 gallons
500 mL 0.132085 gallons
1,000 mL 0.264172 gallons
2,000 mL 0.528343 gallons
5,000 mL 1.32085 gallons
10,000 mL 2.64172 gallons

Gallons to Milliliters Conversion Table

Here is a conversion table showing some common gallon values converted to milliliters:

Gallons Milliliters
0.25 gallons 946.353 mL
0.5 gallons 1,892.705 mL
1 gallon 3,785.41 mL
2 gallons 7,570.82 mL
5 gallons 18,927.05 mL
10 gallons 37,854.1 mL

Using Formulas to Convert Between Gallons and Milliliters

In addition to conversion factors, you can use formulas to convert between gallons and milliliters:

  • Gallons = Milliliters / 3,785.41
  • Milliliters = Gallons x 3,785.41

Plugging values into these formulas gives us:

Milliliters = 5 gallons x 3,785.41 = 18,927.05 mL

Gallons = 10,000 mL / 3,785.41 = 2.64172 gallons

These formulas are based on the definitions and conversion factors between gallons and milliliters. They provide a concise way to carry out the conversions.

Deriving the Gallons to Milliliters Formula

We can derive the formula for converting gallons to milliliters as follows:

  • Start with the conversion factor: 1 gallon = 3,785.41 mL
  • The conversion factor is an equality, so we can set up a fraction:
    1 gallon / 3,785.41 mL = 1
  • Invert the fraction to solve for mL:
    3,785.41 mL / 1 gallon = 1
  • Simplify by dropping the 1’s:
    Milliliters / Gallons
  • Therefore: Milliliters = Gallons x 3,785.41

Using the same process, we can derive the formula for converting milliliters to gallons.

Using the Formulas

The conversion formulas provide a straightforward method for quickly converting between gallons and milliliters. They are especially helpful for converting multiple values without having to repeat the multiplication or division each time. Converting between gallons and milliliters is common for many household, commercial, and scientific applications.

Gallons to Milliliters Converter

You can use the following converter to easily change gallons to milliliters or vice versa:



Enter a value in either the Gallons or Milliliters input. Click the “Convert” button and the tool will automatically calculate the equivalent volume in the other unit.

How the Gallons to Milliliters Converter Works

The converter uses JavaScript to take the input value, perform the calculation between gallons and milliliters, and populate the other input field with the converted volume. Here’s a breakdown of how it works:

  1. Get input value from “Gallons” field
  2. Multiply input by conversion factor of 3,785.41 mL/gallon
  3. Update “Milliliters” field with calculated value
  4. Get input value from “Milliliters” field
  5. Divide input by 3,785.41 mL/gallon to convert to gallons
  6. Update “Gallons” field with calculated value

The user does not have to manually do any multiplication or division – the tool handles it automatically. This allows for quick and easy conversions on the fly.

Converting Gallons to Liters

In some cases you may need to convert between gallons and liters instead of milliliters. Here is how to convert between US gallons and liters:

  • 1 US gallon = 3.78541 liters
  • 1 liter = 0.264172 US gallons

To convert gallons to liters, multiply gallons by 3.78541. For example:

6 gallons x 3.78541 liters/gallon = 22.71246 liters

To convert liters to gallons, divide liters by 3.78541 or multiply by 0.264172. For example:

18 liters x 0.264172 gallons/liter = 4.7551 gallons

So 6 gallons = 22.71246 liters, and 18 liters = 4.7551 gallons. The same gallon to milliliter conversion factors are used, just with liters instead of milliliters.


In summary, one US gallon is equal to 3,785.41 milliliters. Converting between gallons and milliliters is common for cooking, mixing solutions, calculating water usage, and other everyday and scientific applications. Use the conversion factors or formulas to easily convert between the two units. An online converter tool can also simplify gallons to milliliters conversions.

Leave a Comment