Foot to Light-Year Converter
Convert feet to light-years instantly. Free, bidirectional, and fully in-browser.
About this tool
Foot to Light-Year Converter
Convert feet to light-years instantly. Free, bidirectional, and fully in-browser.
1 foot equals 3.221739e-17 light-years — enter any foot value to convert it to light-years instantly. This Foot to Light-Year converter is a client-side tool: it applies a single multiplication (ly = ft × 3.221739e-17) in your browser, updates the moment you type, and works in both directions — edit either field, or press swap, to convert light-years back to feet. A reference table lists common foot values already converted, and nothing you enter is sent to a server.
How to use Foot to Light-Year Converter
- 1
Open Foot to Light-Year Converter on AltFTool — it loads instantly in your browser.
- 2
Type the value you want to convert into the Foot field.
- 3
Read the equivalent in light-years in the result field, and copy it if needed.
- 4
Use the decimal-places slider for more or less precision, or press swap to convert light-years to feet.
Why use Foot to Light-Year Converter
Instant, both ways
The result updates as you type, and the swap button flips the conversion to light-year → foot without reloading.
Exact Length math
The conversion uses the precise factor (ly = ft × 3.221739e-17), so the number matches a manual calculation to the decimal places you choose.
Adjustable precision
A slider sets 0–10 decimal places, and very small or very large results switch to scientific notation instead of rounding to zero.
Private and free
Everything runs locally in your browser — no upload, no account, no limit on conversions.
Common use cases
- Converting a foot measurement to light-years for a spec, listing, or report.
- Checking foot↔light-year figures while comparing products, datasets, or documentation.
- Learning the foot-to-light-year relationship from the worked formula and the common-value table.
Frequently asked questions
How many light-years are in a foot?
One foot is 3.221739e-17 light-years. Multiply the foot value by 3.221739e-17 to convert. For example, 10 ft = 3.221739e-16 ly.
What is the formula to convert feet to light-years?
ly = ft × 3.221739e-17. This tool applies it automatically and shows a worked example: 10 ft = 3.221739e-16 ly.
Can it convert light-years back to feet?
Yes. Press the swap button, or type into the light-year field, and the tool converts light-years to feet using the inverse of the same relationship.
Is the conversion accurate?
It uses the standard distance and length definition (ly = ft × 3.221739e-17), not a rounded approximation, so results are exact to the number of decimal places you select.
Does this work offline and stay private?
Yes. The converter is a browser-side script with no network calls: your values are never uploaded, and once the page has loaded it keeps working without a connection.
Embed this tool on your site
Add the Foot to Light-Year Converter widget to your blog or website — free, responsive, no signup. Just keep the “Widget by AltFTool” credit link visible.
<iframe src="https://www.altftool.com/embed/widget/feet-to-light-years-converter"
title="Foot to Light-Year Converter — free AltFTool widget"
width="100%" height="640" style="border:0;border-radius:12px;overflow:hidden"
loading="lazy" referrerpolicy="no-referrer-when-downgrade" allow="clipboard-write"></iframe>
<p style="font-size:12px;margin:4px 0 0">Widget by <a href="https://www.altftool.com/tools/all/feet-to-light-years-converter?utm_source=embed&utm_medium=widget" rel="nofollow">AltFTool — free online tools</a></p>