gal to L Converter
Convert US gallons into precise liter values
Gallons to liters FAQ
How do you convert US gallons to liters exactly?
This calculator uses the standard definition 1 US liquid gallon = 3.785411784 liters. To go from gal to L, you multiply the gallons value by 3.785411784. For example, 10 gal becomes exactly 37.85411784 L. The tool does this for you and formats the answer so it is easy to read, copy into a form, or compare against tank and bottle labels.
Does this use US gallons or imperial (UK) gallons?
This page is for US liquid gallons only. A US gallon is smaller than an imperial gallon used in the UK and some Commonwealth countries. One US gallon is about 3.785 L, while an imperial gallon is about 4.546 L. If your container or fuel pump is marked “US gal” or you are dealing with US car specs and fuel economy, this is the right converter to use.
Why do car specs show both mpg and L/100 km?
In the US, fuel economy is usually given in miles per gallon (mpg), while most metric countries use liters per 100 kilometers (L/100 km). When you see a tank size in gallons but a consumption figure in L/100 km, you need an accurate gallons to liters conversion to plan range and refueling stops. This calculator gives the tank volume in liters so you can combine it with metric fuel consumption figures or trip-planning tools.
What is 10 gallons in liters for a small tank?
Using the exact factor, 10 gal = 37.85411784 L, which many people round to 37.85 L or 38 L for everyday use. That is a common size for small car tanks, portable fuel cans, and hobby aquariums. You can plug in other values like 5 gal, 15 gal or 20 gal to get the matching volumes in liters for your own setup.
Is a gallon a metric unit of volume?
No. The gallon (gal) is part of the US customary and imperial systems, while the liter (L) is a metric unit accepted for use with SI. In practice, you often see both on the same containers: motor oil jugs, coolant, cleaning products and beverage packages may show US gallons for American buyers and liters for international customers. This converter bridges those two systems.
How many decimal places of liters should I keep?
For most real-world uses, two decimal places in liters are enough. For example, 12 gal → 45.42 L. If you are checking whether a tank meets a minimum capacity or estimating how many brew buckets or aquarium top-ups you need, rounding to the nearest tenth or whole liter is usually fine. The calculator keeps more precision in the background so you can decide how to round for your specific application.
Can I use this for brewing, aquariums and household mixing?
Yes. Many brewing recipes, water-treatment products, pool chemicals and aquarium guides mix US gallons and liters. A quick gal to L conversion lets you scale batch sizes, work out how many liters you actually have in a “5 gal” bucket, and match US-based instructions with metric measuring jugs and dosing syringes.
From US gallons on labels to liters you can compare
This gal to L converter is built for all the situations where volumes are printed in US gallons but you think in liters. That is common with car and boat fuel tanks, pressure washers, chemical containers, beverage kegs and aquarium gear. Instead of memorising 3.785411784 or doing rough head math, you type the gallons, tap convert, and read a clean line such as “10 gal = 37.8541 L”.
1. Simple single-box interface
The interface stays deliberately minimal: one input field for gallons, one result card. You can enter whole numbers like 15 gal for a typical small car tank, or decimal values such as 2.5 gal for a portable can or brew bucket. The converter applies the exact US liquid gallon definition and returns the matching liters, with sensible formatting for everyday reading and copying.
When you need the reverse direction, the “Swap Units” button jumps straight to the dedicated L to gal page. That way, you can move between liters and gallons across both tools without changing how you like to think about your volumes.
2. Exact relationship: 1 US gal = 3.785411784 L
Under the hood, this page uses the legal definition 1 US gallon = 231 cubic inches, which corresponds to 3.785411784 liters. That is the same factor used in official conversion tables and standards documents, so you can trust the output for engineering work, specification sheets and record keeping. If you want to convert other units like milliliters, cubic meters, cups or quarts, the volume conversion calculator covers many more pairings in the same style.
3. Common gal to L values at a glance
Here are some quick examples that match what the calculator produces. They are useful checkpoints when you want to sanity-check a number on a tank, drum or recipe:
| US gallons (gal) | Liters (L) |
|---|---|
| 1 gal | 3.79 L (3.7854 L exact) |
| 2.5 gal | 9.46 L |
| 5 gal | 18.93 L |
| 10 gal | 37.85 L |
| 15 gal | 56.78 L |
| 20 gal | 75.71 L |
| 50 gal | 189.27 L |
| 100 gal | 378.54 L |
A fast mental check is to multiply by four and subtract a little. For example, 10 gal → 40 minus about 2 = roughly 38 L. The calculator uses the exact factor to give you the precise value when you need it for dosing, compliance or documentation.
4. Where the gal to L converter shines
You will most often reach for this tool in situations like:
- Fuel and range planning — translate US-gallon tank sizes into liters to compare cars, boats or generators across markets.
- Brewing and beverage batches — convert “5 gal” or “15.5 gal” recipes into liters so you can use metric kettles and fermenters.
- Aquarium and pond care — match filter and treatment doses given in mL per liter to tanks sold in US gallons.
- Household and cleaning products — understand how many liters of solution you get from a gallon jug or concentrate.
- Spec sheets and engineering — convert legacy US-gallon capacities to metric volumes for reports, tenders and international clients.
Because it is anchored to officially recognised definitions, you can come back to this gallons to liters converter any time and get results that are consistent, predictable and easy to reuse across all your volume calculations.
References and further reading on gallons and liters
These references explain how gallons and liters are defined and used:
- Gallon — describes US and imperial gallons, their history and exact definitions.
- Litre — covers the liter as a metric unit of volume and its relation to cubic metres.
- SI Units — Volume (NIST) — gives official guidance on volume units, including the liter, in the SI framework.
For regulated work, certifications or trade, always follow the conversion and rounding rules specified by your local standards body or industry guidelines.