Acreage Calculator (Four Sides)
Have the four side measurements of a plot but no map? Enter the length of each side in feet and this four-sides acreage calculator estimates the land area in acres, square feet and hectares.
Four Side Lengths → Acreage
Estimate only — four side lengths alone don't fully define a shape. For exact area, measure on a map.
How the Four-Sides Calculation Works
Enter the four sides in order around the plot — top (A), right (B), bottom (C) and left (D). The calculator averages each pair of opposite sides and multiplies them:
Area ≈ ((A + C) ÷ 2) × ((B + D) ÷ 2)
For the example above — A = 200, B = 180, C = 220, D = 200 — the averages are 210 ft and 190 ft, giving 39,900 ft² ≈ 0.916 acres.
Important: Four Sides Alone Aren’t Exact
This is the key thing to understand. Four side lengths do not uniquely define a shape. A quadrilateral with the same four sides can be “flexed” into many different areas depending on its corner angles — think of how a rectangle collapses into a flatter parallelogram while its sides stay the same length.
This calculator assumes the plot is roughly rectangular (opposite sides run parallel), which is a good approximation for most surveyed lots and fields. But for an exact figure you need either the diagonals/angles or a direct measurement.
For a precise result, trace the actual boundary on satellite imagery with the acreage calculator map — it uses the true GPS coordinates of each corner, so the angles are accounted for automatically. If your plot is a simple rectangle, the acreage calculator by feet is also exact.
Frequently Asked Questions
Can you calculate acreage from four sides?
You can estimate it. Averaging opposite sides and multiplying gives a good approximation for a roughly rectangular plot, but four side lengths alone don't define an exact area — the corner angles also matter. For an exact figure, measure the boundary on a map.
Why isn't four sides enough for an exact area?
A four-sided shape can flex: with the same four side lengths the area changes as the corner angles change. You need the diagonals, the angles, or the actual corner coordinates to pin it down exactly.
How can I get an exact acreage instead?
Measure the plot directly on satellite imagery. The Marea acreage calculator uses the real GPS coordinates of each corner, so angles and irregular shapes are handled automatically.
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