Chains in surveying
The surveying (Gunter’s) chain is defined as 66 feet. This is the value you will see in most land survey documents, older plats, and US public land surveys.
The engineer’s chain is a convenient 100 feet. Some construction or engineering specs may quote chains in this way; that’s why this converter lets you switch between 66 ft and 100 ft.
Formulas
feet = chains × chain_length
For surveyor’s chain: feet = chains × 66
For engineer’s chain: feet = chains × 100
chains = feet ÷ chain_length
Survey: chains = feet ÷ 66
Engineer’s: chains = feet ÷ 100
FAQ
1. How many chains in a mile?
With 66 ft chains: 1 mile = 5,280 ft → 5,280 ÷ 66 = 80 chains.
2. What is a furlong?
1 furlong = 10 chains = 660 ft (with the 66 ft chain).
3. Which value should I use?
If you are dealing with historical or cadastral records, pick 66 ft. If your spec explicitly says “100 ft chain”, pick 100 ft.
Formula (LaTeX) + variables + units
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feet = chains × chain_length For surveyor’s chain: feet = chains × 66 For engineer’s chain: feet = chains × 100
chains = feet ÷ chain_length Survey: chains = feet ÷ 66 Engineer’s: chains = feet ÷ 100
- No variables provided in audit spec.
- NIST — Weights and measures — nist.gov · Accessed 2026-01-19
https://www.nist.gov/pml/weights-and-measures - NIST — SI units — nist.gov · Accessed 2026-01-19
https://www.nist.gov/pml/owm/metric-si/si-units
Last code update: 2026-01-19
- Initial audit spec draft generated from HTML extraction (review required).
- Verify formulas match the calculator engine and convert any text-only formulas to LaTeX.
- Confirm sources are authoritative and relevant to the calculator methodology.