Gallons to liters converter
One US liquid gallon is exactly 3.785411784 liters, so a 5-gallon drum holds 18.92705892 liters. Use it when a pump, a jug or a bulk container speaks gallons and your paperwork, lab notes or recipe need liters. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Gallons
- 1
- Result
- 3.785411784 L
- Converted
- 3.785411784
- Liters
- 3.785411784
- From unit
- gal
A gallons-to-liters converter turns a US liquid gallon volume into the SI liter scale used on fuel receipts, laboratory notebooks, export packing lists, and international recipe adaptations. Approximate mental shortcuts such as “times four” are unnecessary here because the factor is exact by definition of the US liquid gallon in SI units—231 cubic inches with one inch exactly equal to 2.54 centimeters—not a survey constant that needs estimation.
Why US gallons convert to liters at exactly 3.785411784
Gallons remain everyday liquid volume units across the United States for fuel pumps, milk jugs, paint cans, and water tanks, while liters dominate international science, medicine, logistics, and most of the world outside US customary practice. Drivers comparing US pump gallons to metric fuel economy, shippers labeling drums for overseas customs, chemists converting lab stock from US bulk containers, and students solving unit-conversion homework all need a single reliable bridge from US gallons to liters.
That bridge is definitional rather than approximate: one US liquid gallon is exactly 231 cubic inches, and the international inch is exactly 2.54 centimeters, so one US liquid gallon equals exactly 3.785411784 liters. Conversion is therefore a single exact multiply—liters equals gallons times 3.785411784—with no leftover uncertainty and no dependence on local survey factors or temperature corrections. This landing stays on the US liquid path only.
It does not convert imperial (UK) gallons, which are larger at 4.54609 liters and would mislead searchers who typed gallons to liters for US fuel or kitchen volumes, and it does not convert dry gallons used for some bulk commodities.
Practical tips, checks, and related searches
Round-trip sanity checks are easy: convert one gallon and confirm you receive exactly 3.785411784 liters after rounding, convert five gallons and confirm 18.92705892 liters, or convert zero and confirm zero. When teaching, show that dividing the published liters by 3.785411784 recovers the original gallons within the same twelve-decimal rounding used for published fields. Stay inside the absolute range so the multiply cannot overflow into a non-finite result the solver must reject.
This landing targets people searching for gallons to liters, convert US gallons to liters, or an exact 3.785411784-factor calculator; it is not a general multi-unit volume hub, not a liters-to-gallons primary form, not an imperial gallon converter, and not a cups-or-quarts path. Prefer this capability when the input is already in US gallons and you only need liters; if you must convert among many volume units in one call, use a broader unit converter instead.
When comparing fuel receipts across countries, remember that this tool multiplies volume only and does not convert price per gallon into price per liter—use a dedicated fuel-price unit converter for that.
What you can do with it
Fuel and travel volume bridging
Convert US pump gallons to liters for trip logs, rental car handovers, and metric fuel-economy comparisons with the same exact factor every fill-up.
Export packing and laboratory stock
Turn US bulk gallon readings into liters for customs declarations, SDS sheets, and lab inventory systems that store capacity in SI units only.
FAQ
Does this convert imperial (UK) gallons?
No. It converts US liquid gallons to liters only. An imperial gallon is 4.54609 L and is not accepted as input on this landing.
Is the gallons to liters converter free?
The browser tool is free and runs locally.
Why is a US gallon exactly 3.785411784 liters?
Because the US liquid gallon is defined as 231 cubic inches, and one inch is exactly 2.54 centimeters. Multiplying those definitions out gives 3.785411784 liters with nothing left to estimate.
How many liters are in 5 gallons?
Five US gallons are 18.92705892 liters. The converter multiplies the gallons by 3.785411784, so you can enter any amount, from a single jug to a full tank, and get the exact figure.
Does it convert a price per gallon into a price per liter?
No. It converts the volume only. To compare fuel costs between countries, convert the quantity here and work out the price per unit separately, because a price changes in the opposite direction.
Related tools
For developers — API access
Everything on this page is available programmatically. This section is for teams who want to wire it into their own systems; everyone else can just use the tool above.
API endpoint
Prefer to automate it? One authenticated POST creates the task; the result comes back by webhook or a signed link. The same capability also runs here on the web, by email and from Telegram — and soon from our app too.
Call it from your stack
curl -X POST https://api.kit.forhosting.com/conv/gallons-to-liters \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"gallons":1}'const res = await fetch("https://api.kit.forhosting.com/conv/gallons-to-liters", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"gallons": 1
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/conv/gallons-to-liters",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"gallons": 1
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/conv/gallons-to-liters", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"gallons":1}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"gallons":1}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/conv/gallons-to-liters", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"gallons": 1
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "conv.gallons_to_liters",
"status": "queued",
"_links": {
"result": "/tasks/tsk_…/result"
}
}The API is asynchronous: the call returns a task_id immediately and the result arrives by webhook. Polling is capped at 1 req/s per task.
Pricing
Published price — no tokens, no invented credits. A failed task is never charged.
Limits
max_abs | 1000000000000 |
Errors
| HTTP | Code | Meaning |
|---|---|---|
401 | unauthorized | Missing or invalid API key. |
402 | insufficient_balance | Your balance doesn't cover the task price. |
404 | unknown_type | That task type doesn't exist. |
429 | rate_limited | Too many requests. Use the webhook instead of polling. |
Technical notes
Invalid or missing input fails with a clear invalid_input error instead of inventing a number.
How to call the API and what comes back
Absolute values must stay within the published limit of one trillion. Prefer bare numbers when you control the client; string numbers are accepted only when they match a strict finite numeric pattern without unit symbols, thousand separators, or currency marks attached to the value. Send a JSON body with one required finite number field named gallons. Aliases gal, gallon, value, volume, us_gallons, and gallons_value are accepted so SDK clients and form posts can use the name that fits the product. On success the response echoes rounded gallons, sets liters, result, and converted to the same rounded liter magnitude, unit to the token L, from_unit to gal and to_unit to L, factor and liters_per_gallon to 3.785411784, formula to the string liters equals gallons times 3.785411784, message to a short English summary, and steps to an ordered array of substitution lines that show the exact US liquid definition. Failed validation—missing fields, non-finite numbers, bare plus or minus signs, non-numeric strings, values outside absolute limits, or a non-finite converted result—returns invalid_input and is never charged. Pricing is a flat $0.002 per successful request with unit item and zero marginal unit price.
Practical tips, checks, and related searches
Failed tasks that return invalid_input do not consume prepaid balance, which keeps exploratory scripts cheap when learners deliberately omit gallons or pass text placeholders while debugging their client code.
Integration use cases
Homework and unit-test fixtures
Students and engineers convert classroom gallon volumes to liters and pin golden JSON so browser and API arithmetic never drift.
Technical questions
What formula converts gallons to liters?
Liters = gallons × 3.785411784. One US liquid gallon is defined as exactly 3.785411784 liters (231 in³ with 1 in = 2.54 cm), so the factor is exact, not an estimate.
Is the factor 3.785411784 exact?
Yes. The US liquid gallon is exactly 231 cubic inches, and the international inch is exactly 2.54 cm, so 1 US gal = 3.785411784 L exactly. This tool multiplies by that constant only.
What happens on missing or non-numeric input?
The API returns invalid_input naming the problem (for example a missing gallons field). Failed tasks are not charged.