Convert Square Chain to Rood
Convert square chains to roods instantly. 1 square chain = 0.4 rood — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Rood to Square Chain converter for the reverse conversion.
Units explained
Square Chain
A square chain is an imperial unit of area equal to approximately 404.686 m². It equals 1/10 of an acre.
Derived by squaring the chain (66 feet or 22 yards). The chain was defined by Edmund Gunter in 1620 specifically so that 10 square chains equal exactly one acre.
Square chains appear in US Public Land Survey System (PLSS) records and historical English property documents. The 10-to-1 ratio with acres made early survey arithmetic easier.
Defined by Edmund Gunter in 1620 specifically for surveying convenience.
Rood
A rood is an imperial unit of area equal to approximately 1011.71 m², or 1/4 of an acre. It was historically used in England and parts of the British Empire.
Defined as one-quarter of an acre; historically used in medieval English farming as the area one ox could plow in a day. The word relates to 'rod' as a measure of length used in plot dimensions.
Roods appear in historical English farming records, parish records, and old property deeds. The unit is functionally obsolete today.
Medieval English farming origin; standardized via the 1959 International Yard and Pound Agreement.
Square Chain to Rood conversion formula
The relationship between square chains and roods:
To convert square chains to roods, multiply the value in square chains by 0.4. To reverse, multiply roods by 2.5000000002.
How to use this converter
Type a value into the calculator. The result in roods updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Rood to Square Chain converter for the reverse direction.
Step-by-step: convert square chains to roods
- Write down the value in square chains (ch²).
- Multiply that value by the factor 0.4.
- The product is the equivalent value in roods (rood).
- To reverse, multiply the rood value by 2.5000000002.
Worked examples
Example 1 — Convert 1 ch² to rood:
1 × 0.4 = 0.4 rood
Example 2 — Convert 100 ch² to rood:
100 × 0.4 = 39.999999996 rood
Square Chain to Rood conversion table
Standard reference values for converting square chains to roods:
| Square Chain [ch²] | Rood [rood] |
|---|---|
| 0.01 | 0.004 |
| 0.1 | 0.04 |
| 1 | 0.4 |
| 2 | 0.7999999999 |
| 3 | 1.1999999999 |
| 4 | 1.5999999998 |
| 5 | 1.9999999998 |
| 10 | 3.9999999996 |
| 20 | 7.9999999992 |
| 30 | 11.9999999988 |
| 40 | 15.9999999984 |
| 50 | 19.999999998 |
| 100 | 39.999999996 |
| 500 | 199.9999999802 |
| 1000 | 399.9999999605 |
Frequently asked questions
How many roods is 1 square chain?
How do I convert square chains to roods?
How do I convert roods back to square chains?
How many roods is 100 square chains?
Popular area unit conversions
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Metric / SI (5 units)
Imperial / US Customary (14 units)
Sources & references
Conversion factor (1 ch² = 0.4 rood) verified against the following authoritative sources:
- BIPM — The International System of Units (SI Brochure 9th ed.)
Official BIPM publication defining the seven SI base units (including the meter) and the rules for their use. The global authority on units of measurement.
- NIST — Guide to the SI
US National Institute of Standards and Technology reference covering the SI base and derived units with definitions and usage rules for US technical practice.
- NIST Special Publication 811 — Guide for the Use of the International System of Units
Detailed NIST guide covering exact conversion factors between SI and US customary units along with formatting and rounding conventions.
- NIST — Refinement of values for the yard and pound (Federal Register 1959)
The treaty (signed by US
- International Astronomical Union — System of Astronomical Constants
The IAU defines astronomical units including the AU (149597870700 m exactly) light-year and parsec used in astronomy and astrophysics.