Square Rods to Square Inches (sq rd to in²)

1 square rod equals 39,204 square inches exactly.

1 square rod = 39,204 square inches

How to convert square rods to square inches

To convert square rods to square inches, multiply the number of square rods by 39,204. This factor is exact. To go the other way, multiply square inches by 0.00002550760127 (rounded).

square inches = square rods × 39,204

Example: 10 square rods = 392,040 square inches.

About these units

Square Rod (sq rd)

US & ImperialTraditional unit (still used in some regions)

30.25 square yards (25.29 m²), also called a perch. 160 square rods make an acre.

Perch is the older name for this small square, and it traces back to the Roman pertica, a measuring pole. The word rod became the preferred surveyors' term in England, where land measurers carrying rods, poles or knotted cords were in demand after Henry VIII took over church estates in 1536. A square rod is the square on a rod of 16.5 feet, which works out to 272.25 square feet, or 30.25 square yards.

The odd-looking number makes sense through the acre. Edmund Gunter's 66-foot chain is four rods long, so a square chain holds 16 square rods, and ten square chains make an acre. That means 160 square rods fill an acre, and a rood holds 40. Metric equivalents are about 25.29 square meters, a little under the floor area of a small garage. Rods and perches turned up in deeds, tax records and plot descriptions for centuries, and a few English-speaking regions still quote small building plots in perches.

1 square rod = 25.29285264 square meters (exactly).

Sources: Wikipedia: Rod (unit); Wikipedia: Chain (unit); Wikipedia: Acre

Square Inch (in²)

US & ImperialCurrent unit

A square one inch on a side, exactly 6.4516 cm². Used for small parts and for pressure (pounds per square inch).

Latin uncia, one twelfth, gave English the inch, which Old English borrowed as ynce. A statute of Edward II in 1324 defined it as three barleycorns, dry and round, set end to end, and the barleycorn remained the base for centuries after 1066. The modern square inch rests on a 20th-century agreement: the United States adopted a yard of exactly 0.9144 meter on 1 July 1959, the United Kingdom followed effective 1 January 1964, and the inch became exactly 25.4 mm.

Squaring that gives exactly 6.4516 cm² for one square inch, and one square meter is about 1,550 of them. Its best-known descendant is the pound per square inch, psi, the pressure unit still used for American tires and air tanks: atmospheric pressure at sea level is about 14.7 psi, a car tire is typically inflated to around 32 psi above the surrounding air, and one psi is about 6.895 kilopascals. The square inch itself is common in the US and UK for small parts and printed material.

1 square inch = 0.00064516 square meters (exactly).

Sources: Wikipedia: Square inch; Wikipedia: Inch; Wikipedia: Pounds per square inch

Related conversions

See all area units.