Acreage Calculator

Estimate plan-view land area from simple dimensions or convert an existing area. Subtract exclusions per plot and combine identical plots without treating a rough estimate as a boundary survey.

CurrencyUse one currency for all amounts. This changes labels only; it does not convert money or change local rules.

Land area method

Dimension unitsChanges convert dimension fields, not an independent area-unit selection.

Length / base / diameterftRectangle length, triangle base, first parallel trapezoid base or circle diameter.

Width / perpendicular heightftFor triangles and trapezoids, use the perpendicular height—not a sloping side.

Other parallel trapezoid baseftTrapezoid mode only. The two base lengths must describe parallel sides.

Measured and excluded area unitsThis controls both the measured-area input and the excluded area per plot.

Already measured area per plotft²Conversion mode only. Use horizontal plan area if comparing land records.

Excluded area per plotft²Subtract once per plot. Do not enter a total across all plots here.

Number of identical plotsplotsFor different shapes or sizes, calculate them separately before adding their areas.

Entered price per acre (optional)USD/acreSimple area × entered price arithmetic, not a land appraisal or market quote.

Calculation results

Total net acreage

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How to use this calculator

Choose a shape or measured area

Use the simple shape that matches the parcel section, or enter a previously measured total. A general irregular boundary cannot be determined from four side lengths alone.

Use horizontal dimensions

The estimate describes plan area. For triangle and trapezoid modes, measure perpendicular height. Sloping ground distances are not automatically converted to horizontal distances.

Subtract exclusions consistently

The exclusion uses its own displayed area units and applies to each identical plot. It cannot exceed the gross area of one plot.

Review the area conversions

The result shows acres, hectares and common square units. Optional price multiplication does not account for access, zoning, improvements or other valuation factors.

Formula and worked example

Rectangle area = length × width
Triangle area = base × perpendicular height ÷ 2
Trapezoid area = (parallel base 1 + parallel base 2) × perpendicular height ÷ 2
Circle area = π × diameter² ÷ 4
Total net area = (gross area per plot − excluded area per plot) × number of identical plots
1 acre = 43,560 ft² = 4,046.8564224 m²
1 hectare = 10,000 m²

A rectangular parcel measuring 330 × 132 ft has 43,560 ft², exactly 1 modern acre. If 4,356 ft² is excluded from each of two identical parcels, each net area is 0.9 acre and the combined result is 1.8 acres. At an entered 10,000 per acre, simple price multiplication gives 18,000 in that currency.

Examples with one plot and no exclusions

Based on the international foot. Do not reinterpret a legacy survey-foot record without confirming its units.
Area	Acres	Square meters
43,560 ft²	1	4,046.8564224
21,780 ft²	0.5	2,023.4282112
10,000 m²	≈ 2.471054	10,000

Frequently asked questions

How many square feet are in an acre?

The acre used here is 43,560 square international feet, equivalent to 4,046.8564224 square meters. Historical survey-foot-based records can have a slightly different metric conversion.

Can I enter four sides of an irregular property?

Not by themselves. Side lengths do not generally determine the area without angles, coordinates, diagonals or other geometry. Split into measured simple sections or use a properly established area.

Is this the same as a legal acreage survey?

No. It does not locate corners, interpret deeds, identify easements or settle boundaries. Use authoritative land records or a qualified survey where those distinctions matter.

Does the calculator account for a hillside?

No automatic slope correction is applied. Land records commonly describe plan area; ground-surface dimensions can describe a different area. Use measurements appropriate to the comparison.

Why have separate dimension and area units?

Lengths and an existing area are different inputs. You can measure a rectangle in meters while entering an exclusion in square feet; the calculator converts both internally before subtraction.

Methodology and sources

Simple, planar shapes and identical-plot multiplication only. No coordinate polygon, geodesic, slope-surface or cadastral calculations are performed. Circle input is diameter, not radius. A triangle/trapezoid requires perpendicular height. The optional price uses net acreage only and is not a valuation model.

NIST — revised unit conversion factors — Exact modern acre, square-foot and metric conversions, with legacy survey-foot factors shown separately.
NIST — US survey foot transition — Why historical survey-foot records must not be silently treated as international-foot measurements. Shape areas use elementary planar geometry.

Sources checked September 1, 2026. Referenced organizations do not endorse Efficienco. Uses the international foot and the modern acre of 4,046.8564224 m². Legacy US-survey-foot areas need their own unit interpretation.