Irregular Land Area Calculator
Measure the area of any odd-shaped parcel. Enter boundary coordinates (X, Y) or the four sides plus a diagonal, and instantly get the area in acres, square feet, square meters and hectares — plus the perimeter.
Enter each corner's X and Y position (from any origin) walking around the boundary. Minimum 3 points. Uses the Surveyor's (Shoelace) formula.
Enter a market price per acre to estimate the parcel's total value.
| Unit | Value |
|---|---|
| Calculate to see all conversions | |
How to use the irregular land area calculator
Four quick steps turn an odd-shaped boundary into a real number — acres, square feet, square meters, hectares, the perimeter, an estimated land value, and a downloadable PDF.
Pick your method
Corner coordinates for any number of sides, or four sides plus a diagonal.
Enter the boundary
Walk the corners in order. Add or remove points as the parcel needs — minimum three.
Add a price per acre
Optional. Turns the acreage into an estimated value for the whole parcel.
Read results & save a PDF
Area in every unit, perimeter, a to-scale boundary drawing, and a corner-by-corner table.
How irregular land area is calculated
Two routes, depending on whether you have positions or lengths. Coordinates go straight into the shoelace formula; four measured sides and a diagonal get split into two triangles and solved with Heron’s. Here is the exact math.
Worked example — a five-sided parcel measured in feet
Corners: (0,0) → (120,10) → (150,90) → (70,140) → (0,100)
Cross-product total: 0 + 9,300 + 14,700 + 7,000 + 0 = 31,000
Area: 31,000 ÷ 2 = 15,500 sq ft
Acres: 15,500 ÷ 43,560 = 0.356 acres
Square meters: 15,500 × 0.092903 = 1,440.0 sq m
Perimeter: 120.4 + 85.4 + 94.3 + 80.6 + 100.0 = 480.8 ft
≈ 15,500 sq ft, 0.356 acres, 0.144 hectares, with a 480.8 ft boundary.
On a parcel priced at $40,000 an acre, that spread is the difference between a $12,200 valuation and a $19,300 one. Squaring off an irregular lot in your head is where most of the error comes from — not the arithmetic.
Land area & boundary charts
The lookups that come up when sizing an odd-shaped parcel — the shoelace method step by step, which method fits your measurements, common acreages, and the unit conversions behind it all.
| Segment | x₁ · y₂ | x₂ · y₁ | Difference |
|---|---|---|---|
| (0,0) → (120,10) | 0 | 0 | 0 |
| (120,10) → (150,90) | 10,800 | 1,500 | 9,300 |
| (150,90) → (70,140) | 21,000 | 6,300 | 14,700 |
| (70,140) → (0,100) | 7,000 | 0 | 7,000 |
| (0,100) → (0,0) | 0 | 0 | 0 |
| Total ÷ 2 | — | — | 15,500 sq ft |
The last segment closes the loop back to corner one — you never re-enter the first point, the formula wraps around on its own.
| What you have | Method | Notes |
|---|---|---|
| Surveyed corner coordinates | Boundary coordinates | The most accurate route — enter them as-is |
| Five or more straight sides | Boundary coordinates | Add one point per corner, no upper limit |
| Four sides plus a diagonal | Four-sided lot | Solved as two triangles sharing the diagonal |
| Four sides only | Not enough | A quadrilateral flexes — measure a diagonal |
| A curved road frontage | Boundary coordinates | Place several points along the arc |
| Lat / long from a phone | Convert first | Project to State Plane or UTM, or convert by hand |
| Metes and bounds on a deed | Convert first | Turn each bearing and distance into an X, Y offset |
Four sides alone is the trap worth remembering: the same four lengths can enclose wildly different areas depending on how the corners hinge.
| Acres | Square feet | Square meters | Hectares |
|---|---|---|---|
| 0.10 ac | 4,356 sq ft | 404.7 sq m | 0.040 ha |
| 0.25 ac | 10,890 sq ft | 1,011.7 sq m | 0.101 ha |
| 0.50 ac | 21,780 sq ft | 2,023.4 sq m | 0.202 ha |
| 1.00 ac | 43,560 sq ft | 4,046.9 sq m | 0.405 ha |
| 2.50 ac | 108,900 sq ft | 10,117.1 sq m | 1.012 ha |
| 5.00 ac | 217,800 sq ft | 20,234.3 sq m | 2.023 ha |
| 10.00 ac | 435,600 sq ft | 40,468.6 sq m | 4.047 ha |
One hectare is 2.471 acres, so a metric listing always reads smaller than the same parcel quoted in acres.
| Convert | Multiply / divide | Where it’s used |
|---|---|---|
| Sq ft → acres | ÷ 43,560 | US land and parcel sizing |
| Sq ft → sq m | × 0.092903 | Metric site plans |
| Sq m → acres | ÷ 4,047 | Reading an overseas parcel listing |
| Acres → hectares | × 0.4047 | Quoting a US parcel abroad |
| Acres → sq miles | ÷ 640 | Ranch, timber, and section land |
| $ per acre → $ per sq ft | ÷ 43,560 | Comparing land and lot pricing |
Match the price basis to the area unit before comparing rates — rural land is usually quoted per acre, suburban lots per square foot.
| Area | Acres | Rough comparison |
|---|---|---|
| 2,788 sq ft | 0.064 ac | One tennis court |
| 4,704 sq ft | 0.108 ac | One basketball court |
| 10,890 sq ft | 0.250 ac | Quarter-acre lot |
| 43,560 sq ft | 1.000 ac | One acre |
| 57,499 sq ft | 1.320 ac | An American football field |
| 217,800 sq ft | 5.000 ac | Small hobby farm |
The calculator shows the same comparison live — football fields, basketball courts, and tennis courts — as you edit the boundary.
The shoelace formula reads a boundary as an ordered walk around the parcel, which is why the sequence of your corners matters more than where you start.
- The origin is arbitrary — only the distances between points matter, so put (0,0) on whichever corner is easiest to measure from.
- Clockwise or counter-clockwise both work — the direction flips the sign, and the formula takes the absolute value.
- Skipping around collapses the area — a crossed boundary counts one lobe as positive and the other as negative, so they cancel instead of adding.
Everything the calculator works out
One boundary gives you the full picture — the parcel in every unit, the distance around it, what it’s worth, and a drawing you can hand to someone else.
The figures behind every land calculation
Built for parcels that refuse to be rectangles
Rural acreage, a pie-shaped cul-de-sac lot, a field bounded by a creek — the same handful of measurements answers all of them.
Checking whether a listed acreage holds up before making an offer, and what the asking price really works out to per acre.
- Enter the corners straight off the plat
- Compare acres against the listing
- Price it per acre before you offer
Quoting an odd-shaped lot accurately in a listing, or sanity-checking county records that disagree with the plat.
- Quote both sq ft and acres
- Flag anything the plat contradicts
- Save the PDF for the file
Sizing seed, fertilizer, or fencing for a field bounded by a creek, a treeline, or a road that bends.
- Add points along curved edges
- Use the perimeter for fencing runs
- Split large tracts into sections
7 tips for measuring an irregular parcel
Small habits that keep a land estimate honest — and stop one mis-ordered corner from throwing out the whole acreage.
Irregular land area calculator FAQ
The area, boundary, and acreage questions people ask most when a parcel won’t square up.
Give every corner an X and Y position, walk around the boundary in order, and run the shoelace formula. A five-sided parcel with corners at (0,0), (120,10), (150,90), (70,140), and (0,100) feet comes to 15,500 sq ft, or 0.356 acres.
If you only measured lengths on the ground, use the four-sided method instead: four boundary lengths plus one diagonal are enough to fix the shape, because the diagonal splits the lot into two triangles that Heron’s formula can solve.
The shoelace formula finds the area of any straight-sided shape from its corner coordinates. For each segment you take x₁ · y₂ − x₂ · y₁, add all the differences together, and halve the absolute total.
It’s called the shoelace method because the cross-multiplications criss-cross down the list of coordinates. Surveyors have used it for centuries, and it works for any number of corners as long as the boundary doesn’t cross itself.
Measure all four boundary lengths plus one diagonal between opposite corners. Four sides on their own don’t define a shape — a quadrilateral can flex like a hinge while its sides stay the same length. The diagonal locks it.
With sides of 120, 90, 110, and 100 feet and a 140 ft diagonal, the lot splits into two triangles of about 5,351 and 5,464 square feet, giving 10,816 sq ft or 0.248 acres in total.
Not directly. This calculator expects a flat X and Y grid in feet, yards, or meters, and degrees of latitude and longitude are not equal distances.
Either export your points in a projected system such as State Plane or UTM, which are already in feet or meters, or convert by hand: one degree of latitude is roughly 364,000 ft everywhere, while one degree of longitude is roughly 364,000 ft × cos(latitude).
Work out the area in square feet, then divide by 43,560. A parcel of 15,500 square feet is 0.356 acres; 21,780 square feet is exactly half an acre.
Working in meters, divide square meters by 4,047 for acres, or by 10,000 for hectares. The calculator shows all four units at once so you don’t have to convert.
Approximate the curve with several straight segments. Add extra boundary points along the arc rather than jumping corner to corner, and the polygon will hug the true edge closely.
Five or six points across a gentle road frontage curve usually gets within a fraction of a percent. A recorded plat describes that same curve with a radius and arc length, so treat your result as an estimate until the survey confirms it.
The usual cause is entering corners out of sequence. Walking the boundary in order matters, because jumping across the parcel makes the outline cross itself and the overlapping halves cancel out.
The other common causes are fewer than three points, mixing units between measurements, or — on the four-sided method — side lengths and a diagonal that can’t physically close into a lot. The calculator flags that last case rather than guessing.
No. This is a planning estimate calculated from the measurements you enter, treating the boundary as straight lines between the points you supplied. It doesn’t know your jurisdiction’s zoning, easements, right-of-way, or floodplain, and it can’t reproduce curves, arcs, or metes-and-bounds calls exactly.
For a permit application, a deed, a mortgage, or a boundary dispute you need the recorded plat and a licensed surveyor. Use this to size up a parcel before that stage.
Not a Survey — Planning Estimate Only: This calculator computes area, perimeter, and unit conversions from the coordinates or lengths you enter, assuming a simple non-overlapping boundary made of straight segments between your points. Curved boundaries, arcs, and metes-and-bounds calls are approximated, not reproduced. Actual boundaries are established only by a licensed surveyor and the recorded plat or legal description, and results here carry no legal standing for permitting, deeds, financing, boundary disputes, or subdivision. The figures do not reflect easements, right-of-way, floodplain, wetlands, setbacks, or any portion of the parcel that may be unusable. Land value is a simple rate multiplication and is not an appraisal; access, utilities, zoning, topography, and frontage materially affect real market value. For planning purposes only.