How do I convert fathoms to thou?

Multiply the fathom value by 72,000. For example, 0.5 fathoms = 36,000 thou.

Is this conversion used?

Not directly. Maritime equipment uses fathoms for rope length and thou for coating thickness, but they are never compared. The conversion exists for completeness.

Fathoms to Thou (ftm to thou) Converter

1 ftm = 72,000 thou

1 Fathom equals 72,000 Thou (1 ftm = 72,000 thou). Convert Fathoms to Thou with formula, table, and examples.

One fathom equals exactly 72,000 thou (mils). Since 1 fathom = 72 inches and 1 inch = 1,000 thou, multiply 72 by 1,000. The fathom measures ocean depth, the thou measures thin coatings and PCB features. They never overlap in practice.

How to Convert Fathoms to Thou

thou = ftm × 72,000

Multiply the value in Fathoms by 72,000

Take your value in Fathoms
Multiply by 72,000
Read the result in Thou

Common Fathoms to Thou Conversions

Fathoms (ftm)	Thou (thou)	Status
0.00001 ftm	0.72 thou
0.0001 ftm	7.2 thou
0.001 ftm	72 thou
0.01 ftm	720 thou
0.1 ftm	7,200 thou
0.5 ftm	36,000 thou
1 ftm	72,000 thou
5 ftm	360,000 thou
10 ftm	720,000 thou
50 ftm	3,600,000 thou
100 ftm	7,200,000 thou

Good to Know About Fathoms to Thou Conversion

A ship's anchor chain has its coating measured in thou (mils) for corrosion protection, while its deployed length is measured in fathoms for navigation. Both measurements describe the same chain at different scales.

Fathoms to Thou: What You Need to Know

A fathom of water is 72,000 thou deep. A human hair at 3 thou is 0.0000417 fathoms. Anchor chain coating thickness might be 10-20 thou, while the chain's deployed length is measured in fathoms. These units coexist in maritime equipment but are never directly converted.

What is a Fathom? ftm

Exactly 6 feet (1.8288 m). Traditionally used to measure water depth in nautical contexts. Originally based on the span of outstretched arms.

Imperial water depth nautical marine charts

Learn more about Fathom →

What is a Thou? thou

One thousandth of an inch (0.0254 mm). Also called a mil in the US. Used in engineering, manufacturing, and for measuring thin materials like plastic film.

Imperial engineering plastic film thickness wire gauges

Learn more about Thou →

Going the other way? Use our Thou to Fathoms converter.

Fathoms to Thou FAQ

One fathom contains exactly 72,000 thou (mils). Since 1 fathom = 72 inches and 1 inch = 1,000 thou.
Multiply the fathom value by 72,000. For example, 0.5 fathoms = 36,000 thou.
Not directly. Maritime equipment uses fathoms for rope length and thou for coating thickness, but they are never compared. The conversion exists for completeness.

Non-Frequently Asked Questions About Fathoms to Thou

Questions nobody should ask - but someone did.

A typical steel ship hull is about 10-25 mm thick, or 394-984 thou. In fathoms, that is 0.0055-0.0137 fathoms. A ship's hull is about 1/180 to 1/73 of a fathom thick. The thin skin between you and the ocean is measured in thou, not fathoms.
Marine paint is applied in coats of about 3-5 thou each. A fully painted hull has about 10-15 coats = 30-75 thou of paint. In fathoms, that is 0.0016-0.0041 fathoms. Your ship's rust protection is about 4 thousandths of a fathom thick.
A thou is 0.0254 mm. In fathoms, that is 0.0000139 fathoms. No depth gauge has ever measured in thou, and no machinist has ever needed fathoms. These units exist in parallel professional universes that overlap only mathematically.