Methodology & accuracy
Every number this site produces, where it comes from, and what we do not do.
Conversion factors verified
What this site is
FT to Miles is a set of seven unit converters built around one relationship: a mile is exactly 5,280 feet. Everything else here — nautical miles, area, speed, mil — either derives from that constant or exists because people routinely confuse a unit with it.
There is no account, no paywall and no server-side processing. Every calculation is JavaScript running in your browser. That is a privacy property, but it is mainly an accuracy one: there is no network round trip to introduce staleness between what you type and what you see.
Where the constants come from
None of the values below are measurements. They are definitions, agreed by international treaty, which means they carry no uncertainty and will not change.
| Unit | Exact value | Source |
|---|---|---|
| 1 mile | 5,280 ft = 1,609.344 m | International Yard and Pound Agreement, 1959 |
| 1 foot | 0.3048 m | International Yard and Pound Agreement, 1959 |
| 1 nautical mile | 1,852 m = 6,076.11549 ft | International Hydrographic Conference, 1929 |
| 1 square mile | 27,878,400 sq ft | Derived: 5,280² |
| 1 ft/s | 0.681818… mph (3,600 ÷ 5,280) | Derived from the mile and the hour |
| 1 foot | 12,000 mil | Derived: 12 in × 1,000 mil |
How we round
We do not round during calculation. Conversion functions return full floating-point precision, and rounding happens exactly once, at the moment a figure is drawn on screen, at the number of decimal places you select.
This matters more than it sounds. Tools that round at each step accumulate error across a multi-unit conversion, and they fail the round-trip test: convert a value and convert it straight back, and you should get your original number. Here you do.
The precision control goes to ten decimal places. Beyond that, the digits are artefacts of binary floating-point representation rather than information about your distance, so we cap it deliberately — unlike some converters that will happily show you fourteen.
Policy
What we deliberately do not do
- We do not use the US survey foot. It was deprecated at the end of 2022 and differs from the international foot by about two parts per million. If you are working from pre-2023 US geodetic records, check which foot they use — this site always uses the international foot of 0.3048 m.
- We do not round to a fixed precision. You choose, from 0 to 10 decimal places. A converter that decides for you is hiding a judgement call.
- We do not treat mil as a mile. They differ by a factor of 63 million and have separate calculators for exactly that reason.
- We do not build city-distance tools. Searches like “miles from Ft Lauderdale to Key West” read ‘Ft’ as the city, not the unit. That is a different product and we have deliberately left it out rather than blur what this site is about.
- We do not track what you convert. The values never leave your device, so there is nothing to collect.
Corrections
Found an error?
If any figure on this site disagrees with an authoritative source, we want to know. Conversion constants are settled facts, so a discrepancy is a bug rather than a difference of opinion.
Going the other way, miles to feet does the reverse conversion. If you want a figure already worked out, conversion chart lists the common ones, and faq documents every constant used here and where it comes from.
Write to gemprogrammersgp@gmail.com or use the contact page. Corrections to constants are applied immediately and noted in the changelog.
Primary sources
- International Yard and Pound Agreement (1959) — foot, yard, mile
- NIST Handbook 44 and NIST Special Publication 811 — US practice
- BIPM SI Brochure, 9th edition — metric definitions
- International Hydrographic Organization, Resolution 1/1929 — nautical mile
- NOAA / NGS notice on the deprecation of the US survey foot (2022)
Methodology FAQ
Questions about how these numbers are produced
Where do the conversion constants on this site come from?
How accurate are the results?
Do you use the US survey foot?
Are the numbers I type sent to a server?
What happens if I find a wrong figure?
Privacy
Your numbers never leave your browser
Every conversion on this site is arithmetic performed by your own device. There is no server round-trip, because nothing is sent.
- No data is transmitted. The calculators are client-side JavaScript — what you type stays on the page.
- No account, ever. No sign-up, no email, no paywall, no usage limit.
- HTTPS end to end. The whole site is served over TLS with no mixed content.
- Works offline once loaded. Because the maths is local, it keeps working if your connection drops.
Now go convert something
Seven calculators, all built on the constants above, all running in your browser.