About

Land area miscalculation propagates through legal documents, property valuations, and tax assessments. A single error in converting between acres and perches can misrepresent parcel size by orders of magnitude in countries where the perch remains a statutory unit (Sri Lanka, parts of Ireland, historical British surveys). This tool applies the exact conversion factor: 1 acre = 160 perches, derived from the definitions 1 acre = 4,840 yd² and 1 perch = 30.25 yd². No rounding is introduced until final display. The tool assumes the international statute perch (also called rod or pole). Regional perch variants (Irish perch = 49 yd², customary Sri Lankan perch = 25 yd²) differ and are listed in the reference table below.

Formulas

The conversion between acres and perches uses a single exact ratio derived from the statutory definitions of both units.

P = A × 160

where P = area in perches, A = area in acres, and 160 is the exact conversion factor.

This factor is derived from the base definitions:

1 acre = 4,840 yd²

1 perch = 30.25 yd² = (16.5 ft)² ÷ 9

4,84030.25 = 160 (exact, no rounding)

The inverse conversion is equally exact:

A = P160

For metric equivalents: 1 perch = 25.29285264 m² and 1 acre = 4,046.8564224 m².

Reference Data

Unit	Equivalent in yd²	Equivalent in m²	Perches per Unit	Acres per Unit	Notes
Statute Perch (Rod/Pole)	30.25	25.2929	1	0.00625	Standard English/international perch
Acre	4,840	4,046.86	160	1	International statute acre
Rood	1,210	1,011.71	40	0.25	1 acre = 4 roods
Square Chain	4,840	4,046.86	160	1	Gunter's chain squared (66 ft)² ÷ 10
Irish Perch	49	40.9676	1	0.01012	Used in historical Irish surveys
Irish Acre	7,840	6,555.39	160 (Irish)	1.62 (statute)	Larger than statute acre
Sri Lankan Perch	25	25.2929	1	0.00516	Customary in Sri Lankan land deeds
Hectare	11,959.9	10,000	395.37	2.4711	SI-preferred land area unit
Square Meter	1.19599	1	0.03954	0.000247	SI base area
Square Foot	0.11111	0.0929	0.003673	0.00002296	Common in US real estate
Square Yard	1	0.83613	0.03306	0.000207	Base unit for perch/acre definitions
Square Mile	3,097,600	2,589,988	102,400	640	1 section of land (US PLSS)
Chain (Gunter's)	-				66 ft linear; 1 acre = 10 sq. chains
Furlong × Chain	4,840	4,046.86	160	1	Historical definition of 1 acre

Frequently Asked Questions

Both units are defined in terms of square yards. One acre is exactly 4,840 yd² and one statute perch is exactly 30.25 yd² (16.5 ft × 16.5 ft ÷ 9). Dividing 4,840 by 30.25 yields exactly 160. No approximation is involved because both definitions share integer roots in the imperial system. The chain-based definition (1 acre = 10 square chains, 1 chain = 4 rods) confirms this: 4 × 40 = 160.

Yes. The statute perch, rod, and pole are three names for the identical unit: a linear measure of 16.5 feet (5.5 yards) and an area measure of 30.25 square yards (272.25 ft²). The term "perch" is more common in land surveying in Sri Lanka, Ireland, and parts of England, while "rod" is prevalent in North America. All three are interchangeable in this conversion.

No. This tool uses the international statute perch (30.25 yd²). The Irish perch equals 49 yd² (7 yards linear), giving 1 Irish acre = 160 Irish perches = 7,840 yd² ≈ 1.62 statute acres. The customary Sri Lankan perch is approximately 25 yd² (close to 25.29 m²), yielding about 193.6 Sri Lankan perches per statute acre. For these variants, multiply your result by the appropriate ratio from the reference table.

The tool displays up to 10 significant digits, which exceeds the precision of any practical land survey. Since the conversion factor is exactly 160 (an integer), no precision is lost in the multiplication or division. Any rounding occurs only at the display level. For legal or cadastral purposes, the result is exact.

The hierarchy is: 1 acre = 4 roods = 160 perches. Therefore 1 rood = 40 perches. This structure descends from medieval English land measurement where a rood was a strip 1 furlong (660 ft) long and 1 rod (16.5 ft) wide. Four such strips made an acre. These relationships are all exact integer multiples.

Yes. The tool accepts any positive numeric input including very large values. For example, a 640-acre section (1 square mile in the US Public Land Survey System) equals exactly 102,400 perches. The JavaScript Number type supports values up to approximately 9 × 10¹⁵ with integer precision, far exceeding any practical land area on Earth.