A volume converter takes a known volume in one unit — liters, gallons, cups, ounces, or cubic inches — and converts it accurately to any other volume unit, without needing to remember or look up conversion factors. This page covers how this converter works, several worked examples converting common volume units, and an important distinction: volume unit conversion (what the convert-units mode does) versus geometric volume calculation (working out the volume of a shape like a cylinder or tank). Browse all converters if you need a different tool.
How This Volume Converter Works
Unit Conversion vs. Distinguishing US and Imperial Gallons
This converter distinguishes between US gallons and Imperial gallons — two different units with the same name but different actual volumes (a US gallon is about 3.785 liters, while an Imperial gallon is about 4.546 liters). This distinction matters and is a common source of conversion errors on calculators that don't clearly separate the two, so this converter labels them explicitly to avoid confusion.
Metric Conversion: Liters, Milliliters, and Cubic Meters
Within the metric system, volume conversion is based on powers of 10:
| Unit | Liters |
|---|---|
| 1 milliliter (mL) | 0.001 L |
| 1 liter (L) | 1 L |
| 1 cubic meter (m³) | 1,000 L |
Converting Between Metric and US Units
Example: 80 mL to Ounces
80 mL ÷ 29.5735 mL per fl oz ≈ 2.71 fl oz
Example: 180 mL to Ounces
180 mL ÷ 29.5735 mL per fl oz ≈ 6.09 fl oz
These types of small-volume conversions come up constantly for things like recipe measurements, medication dosing containers, or product packaging comparisons between metric and US labeling.
Worked Examples: Common Volume Conversions
Beyond milliliters to ounces, this converter handles the full range of common volume conversions — liters to US gallons (1 L ≈ 0.264 US gal), US cups to milliliters (1 US cup ≈ 236.6 mL), and Imperial gallons to liters (1 Imperial gal ≈ 4.546 L), among others.
Volume Conversion Chart
| From | To | Conversion Factor |
|---|---|---|
| 1 liter | US gallons | ≈ 0.264 gal |
| 1 liter | Imperial gallons | ≈ 0.220 gal |
| 1 US gallon | Liters | ≈ 3.785 L |
| 1 Imperial gallon | Liters | ≈ 4.546 L |
| 1 US cup | Milliliters | ≈ 236.6 mL |
| 1 US fluid ounce | Milliliters | ≈ 29.57 mL |
Cubic Inch and Other Volume Units
How This Converter Handles Cubic Inches
Cubic inches are commonly used for smaller volumes in engineering, engine displacement, and some packaging contexts. 1 cubic inch is exactly 16.387064 milliliters (the cube of the international inch). Convert a cubic inch figure to milliliters first, then use this page to move between liters, gallons, or cups.
Geometric Volume Calculation — A Different Kind of "Volume"
Cylinder, Rectangle, and Tank Volume — Not the Same as Volume Conversion
It's worth being clear about an important distinction: converting a known volume between units (like 2 liters to gallons) is not the same as calculating the volume of a physical shape from its dimensions. Geometric volume uses formulas specific to each shape:
- Cylinder volume: V = π × r² × h (radius squared, times pi, times height)
- Rectangular volume (a box or tank): V = length × width × height
- Pipe volume: calculated the same way as a cylinder, using the pipe's internal radius and length
This page's convert-units mode handles the conversion step once a volume is already known. For more calculators, browse the calculators hub.
Frequently Asked Questions
How do I convert liters to gallons?
Multiply the liter value by approximately 0.264 for US gallons, or 0.220 for Imperial gallons, since the two gallon units differ in size.
What is 80 mL in ounces?
80 milliliters is approximately 2.71 fluid ounces.
What is 180 mL in ounces?
180 milliliters is approximately 6.09 fluid ounces.
What's the difference between a US gallon and an Imperial gallon?
A US gallon is about 3.785 liters, while an Imperial gallon is about 4.546 liters. They are different sizes despite sharing the name gallon.
Does this converter handle cubic inches?
Yes. Cubic inches convert to and from liters, gallons, and milliliters using the exact conversion factor of approximately 16.387 milliliters per cubic inch.
Can this calculator find the volume of a cylinder or tank from its dimensions?
No. This tool converts a known volume between units. Calculating a shape's volume from its dimensions uses a different geometric formula specific to that shape.
What's the formula for a cylinder's volume?
Volume equals pi times radius squared times height.
Is this volume converter free to use?
Yes. It is free, requires no sign-up, and converts volume units instantly.