Skip to calculator
FTtoMiles

Feet to Mil Calculator

12,000.0000

1 feet = 12,000.0000 mil (thou)

4

Common values

Convert feet to mil — thousandths of an inch — and back. One foot is 12,000 mil. A mil is not a mile, and the difference is a factor of about 63 million.

  • Exact: 1 mile = 5,280 ft
  • Live as you type
  • Free, no sign-up
  • Stays in your browser

Looking for miles? A mil is a thousandth of an inch — nothing to do with the mile. Use the ft to miles calculator instead.

How do you convert ft to mil?

Multiply the number of feet by 12,000. A mil is one thousandth of an inch, and there are 12 inches in a foot, so one foot contains 12,000 mil. For example, 2 ft × 12,000 = 24,000 mil. A mil is a thickness unit and has no relationship whatsoever to the mile.

Formula

mil = feet × 12,000

feet = mil ÷ 12,000

1 mil = 0.001 inch = 0.0254 mm. Also called a 'thou'. It is not a millimetre, and it is emphatically not a mile.

Conversion factors verified

What is a mil, and how does it differ from a mile?

A mil is one thousandth of an inch, which is 0.0254 millimetres exactly. It measures thickness — plastic sheeting, coatings, foil, laminate, machining tolerances — and despite the similar name it has no relationship whatsoever to the mile. One foot is 12,000 mil, because a foot is 12 inches and each inch is 1,000 mil. One mile is 63,360,000 mil, a difference of eight orders of magnitude, which is why confusing the two is not a rounding error but a catastrophic one. Britain calls the unit a thou precisely to avoid this collision. Common reference points: standard vapour barrier under a concrete slab is 6 mil, or 0.1524 mm, and a plastic card is roughly 30 mil. A human hair is about two to three mil, which makes the unit easy to picture once the name stops misleading you.

Overview

About the feet to mil converter

The mil — also called a thou — is one thousandth of an inch. It is the working unit for thickness in manufacturing: plastic sheeting, paint and powder coatings, PCB copper, wire insulation, foil and film are all specified in mil.

It appears here because 'ft to mil' is a genuine search with genuine volume, and almost everyone who types it is either dealing with a spec sheet or has confused mil with mile. This page handles both cases: the converter does the arithmetic, and the page states the distinction plainly.

For scale: a sheet of standard printer paper is about 4 mil thick. A credit card is about 30 mil. A foot is 12,000 mil — three thousand sheets of paper stacked up.

Method

How it's calculated

Multiply by 12,000. A foot is 12 inches, and each inch is 1,000 mil, so 12 × 1,000 = 12,000 mil per foot. The factor is exact, since both the inch-to-foot and mil-to-inch relationships are definitions.

In metric terms, 1 mil is 0.0254 millimetres exactly, because an inch is defined as exactly 25.4 mm. This means 1,000 mil is 25.4 mm, and a foot is 304.8 mm — which is the same 0.3048 metre definition used everywhere else on this site.

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 about & methodology documents every constant used here and where it comes from.

Examples

Worked examples

The arithmetic in full, using values people search for.

One foot in mil

  1. 1A foot is 12 inches.
  2. 2Each inch is 1,000 mil.
  3. 3Multiply: 12 × 1,000.

1 ft = 12,000 mil exactly.

6 mil plastic sheeting, in feet

  1. 1Start with a thickness of 6 mil.
  2. 2Divide by 12,000.
  3. 3Express in scientific notation for clarity.

6 mil = 0.0005 ft, or 0.152 mm — standard heavy-duty vapour barrier.

Mil against mile — the scale of the confusion

  1. 11 mile = 5,280 ft = 63,360 inches.
  2. 21 inch = 1,000 mil, so 1 mile = 63,360,000 mil.
  3. 3Compare that with a single mil.

1 mile = 63,360,000 mil. Confusing the two is a 63-million-fold error.

Key facts

What to remember

  • 1 mil = 0.001 inch = 0.0254 mm exactly. Also called a thou.
  • 1 foot = 12,000 mil. 1 inch = 1,000 mil.
  • 1 mile = 63,360,000 mil — the two units differ by more than seven orders of magnitude.
  • A mil is not a millimetre. 1 mil is 0.0254 mm, so a millimetre is about 39.4 mil.
  • Common thicknesses: printer paper ≈ 4 mil, a credit card ≈ 30 mil, heavy plastic sheeting 6–10 mil.
  • In a military context 'mil' can also mean a milliradian, an angular unit. That is a third, unrelated meaning.

Accuracy

Assumptions and precision

Every constant in this conversion is exact: the inch is defined as 25.4 mm, the foot as 12 inches, and the mil as one thousandth of an inch. There is no measurement uncertainty anywhere in the chain.

The calculator never rounds internally. Rounding happens once, when a figure is drawn on screen, at the precision you choose with the slider — so converting a value and converting it back returns your original number exactly.

Applications

Who uses this conversion

The same arithmetic, for different reasons.

Manufacturing and QA engineers

Coating thickness, film gauge and plating depth are all specified in mil. Tolerances are often a fraction of a single mil.

Contractors and builders

Vapour barriers and sheeting are sold by mil thickness — 6 mil versus 10 mil is a code-compliance question, not a preference.

PCB and electronics designers

Trace widths, clearances and copper weights are given in mil. Board houses quote minimums in mil, not millimetres.

Anyone who searched for the wrong unit

If you meant miles rather than mil, the feet-to-miles calculator is one click away. The two are not related in any way.

More converters

Related calculators

Every tool here uses the same exact constants and the same live-as-you-type engine.

FAQ

Mil and thou, answered

Direct answers to the questions people search for on this topic.

How many mil are in a foot?

There are exactly 12,000 mil in a foot. A foot is 12 inches and each inch is 1,000 mil, so 12 × 1,000 = 12,000. In metric terms a foot is 304.8 mm, and each mil is 0.0254 mm.

Is a mil the same as a mile?

No, and the difference is enormous. A mil is one thousandth of an inch — 0.0254 mm. A mile is 5,280 feet, or 63,360,000 mil. They are different by a factor of over 63 million, and the similar spelling causes real errors in specifications.

Is a mil the same as a millimetre?

No. One mil is 0.0254 millimetres, so a millimetre is about 39.37 mil. Specifications written in mil are usually American; those in millimetres are usually metric. Reading one as the other introduces a roughly 39-fold error.

How thick is 6 mil plastic in feet?

6 mil is 0.0005 feet, or 0.152 millimetres. Six-mil sheeting is the common specification for vapour barriers and heavy-duty construction covers. For comparison, standard printer paper is about 4 mil and a credit card is roughly 30 mil.

Why is a mil also called a thou?

Both names mean the same thing: one thousandth of an inch. 'Thou' is the usual term in British engineering, 'mil' in American. The two are interchangeable, though 'mil' is ambiguous in military contexts where it can also mean a milliradian.

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.

privacy policy · accuracy methodology

Convert thickness now

Feet, mil, inches and millimetres — converted live. Looking for miles instead? The main calculator is one click away.

Convert my distance nowRead the guides