# Fathoms to Thou (ftm to thou)

Source: https://www.unitconvertercalculator.com/length/fathoms-to-thou/

**1 ftm = 72000 thou**

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.

## Formula

Convert Fathoms to Thou

## Conversion Table

| Fathoms (ftm) | Thou (thou) |
|---|---|
| 1.0E-5 ftm | 0.72 thou |
| 0.0001 ftm | 7.2 thou |
| 0.001 ftm | 72 thou |
| 0.01 ftm | 720 thou |
| 0.1 ftm | 7200 thou |
| 0.5 ftm | 36000 thou |
| 1 ftm | 72000 thou |
| 5 ftm | 360000 thou |
| 10 ftm | 720000 thou |
| 50 ftm | 3600000 thou |
| 100 ftm | 7200000 thou |

## Units

### 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.

### 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.

## Background

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.

## Good to Know

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.

## FAQ

### How many thou are in 1 fathom?

One fathom contains exactly 72,000 thou (mils). Since 1 fathom = 72 inches and 1 inch = 1,000 thou.

### 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.

## Non-Frequently Asked Questions

### How thick is a ship's hull in fathoms?

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.

### How many layers of paint does a ship carry?

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.

### Is a thou of depth even measurable?

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.

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## See Also

- [Thou to Fathoms](https://www.unitconvertercalculator.com/length/thou-to-fathoms/)