# US gallons to Liters (gal (US) to L)

> Convert US gallons to liters: 1 gal (US) = 3.78541 L. Exact conversion factor, formula, 22-row table and worked examples, with JSON API and MCP access.

- Page id: `gallons-to-liters` · Quantity: Volume (`volume`, base unit L) · Tool: `convert_units`
- Canonical page: https://tttkmbb.com/conversion/gallons-to-liters · This document: https://tttkmbb.com/conversion/gallons-to-liters.md · JSON: https://tttkmbb.com/conversion/gallons-to-liters.json (add `?value=` for a result)

## Formula

- `1 gal (US) = 3.78541 L`
- `liters = US gallons × 3.785411784`
- Reverse: `US gallons = liters × 0.2641720524`

The factor follows from the SI definitions of both units (NIST SP 811); values below are rounded to 6 significant figures, the API returns up to 12.

## Worked examples

- 5 gal (US) = 18.9271 L
- 12.5 gal (US) = 47.3176 L
- 100 gal (US) = 378.541 L

## Conversion table

| US gallons (gal (US)) | Liters (L) |
| --- | --- |
| 1 | 3.78541 |
| 2 | 7.57082 |
| 3 | 11.3562 |
| 4 | 15.1416 |
| 5 | 18.9271 |
| 6 | 22.7125 |
| 7 | 26.4979 |
| 8 | 30.2833 |
| 9 | 34.0687 |
| 10 | 37.8541 |
| 15 | 56.7812 |
| 20 | 75.7082 |
| 25 | 94.6353 |
| 30 | 113.562 |
| 40 | 151.416 |
| 50 | 189.271 |
| 75 | 283.906 |
| 100 | 378.541 |
| 200 | 757.082 |
| 250 | 946.353 |
| 500 | 1892.71 |
| 1000 | 3785.41 |

## API

- `GET https://tttkmbb.com/api/v1/convert?value=5&from_unit=gal_us&to_unit=L` → unified JSON envelope with `result.values.result`, `formula`, `factor`, `sources`, `freshness`
- MCP: server `https://tttkmbb.com/mcp`, tool `convert_units` with `{"value":5,"from_unit":"gal_us","to_unit":"L"}`
- All volume units: https://tttkmbb.com/api/v1/units?quantity=volume · full converter: [Volume Converter](https://tttkmbb.com/conversion/volume.md)
- Authentication: none. Freshness: `static` (fixed conversion factors).

## FAQ

**How many liters are in one gallon?**

1 gal (US) = 3.78541 L. The factor comes from the SI definitions of both units (NIST SP 811 / BIPM), so it is exact or correct to at least 10 significant figures.

**What is the formula to convert US gallons to liters?**

Multiply the value in US gallons by 3.785411784: liters = US gallons × 3.785411784. For example, 5 gal (US) = 18.9271 L.

**How do I convert liters back to US gallons?**

Multiply by the inverse factor 0.2641720524 (US gallons = liters × 0.2641720524), or use the liters-to-US gallons page.

## Related conversions

- [Liters to US gallons](https://tttkmbb.com/conversion/liters-to-gallons.md) (reverse)
- [Milliliters to US fluid ounces](https://tttkmbb.com/conversion/ml-to-fl-oz.md)
- [US fluid ounces to Milliliters](https://tttkmbb.com/conversion/fl-oz-to-ml.md)
- [Liters to Milliliters](https://tttkmbb.com/conversion/liters-to-ml.md)
- [Milliliters to Liters](https://tttkmbb.com/conversion/ml-to-liters.md)
- [US cups to Milliliters](https://tttkmbb.com/conversion/cups-to-ml.md)
- [Milliliters to US cups](https://tttkmbb.com/conversion/ml-to-cups.md)
- [US tablespoons to Milliliters](https://tttkmbb.com/conversion/tablespoons-to-ml.md)
- [Milliliters to US tablespoons](https://tttkmbb.com/conversion/ml-to-tablespoons.md)

## Data Sources

- NIST Special Publication 811 – Guide for the Use of the International System of Units (SI), Appendix B conversion factors — https://www.nist.gov/pml/special-publication-811 (standard, retrieved 2026-09-24)
- BIPM – The International System of Units (SI Brochure, 9th edition) — https://www.bipm.org/en/publications/si-brochure (standard, retrieved 2026-09-24)
- Wikipedia – Conversion of units — https://en.wikipedia.org/wiki/Conversion_of_units (reference, retrieved 2026-09-24)