How to Calculate Land Area from Plot Dimensions: Four Sides, Length × Width & Triangle
Learn how to calculate land area from plot side lengths — rectangle, four-sided irregular plots, and triangles — then convert Sq Ft into Decimal, Katha, Bigha, and Acre with clear formulas.
Find Decimal (Shotok), Katha, Bigha & Acre from a plot’s four sides or length × width — or convert any land unit. Supports Feet, Hat, Gaz, Meter & Inch.
From Side Lengths to Land Units
Most land conversion articles assume you already know the area in Katha, Decimal, or Acre. In the field, buyers and surveyors often start with measured side lengths — North, South, East, West — or a simple length × width tape reading. Converting those dimensions into Square Feet first, then into Decimal (Shotok), Katha, Bigha, or Acre, is the reliable way to verify deed claims and negotiate price.
Use the free Land Area Calculator for four-side, length × width, triangle, and trapezoid modes. For dedicated shapes, try the four-side land calculator or triangle land plot calculator.
Method 1: Length × Width (Rectangular Plots)
For a roughly rectangular plot:
Then convert:
Example: 60 ft × 40 ft plot
Method 2: Four Sides (Average of Opposite Sides)
Rural plots are rarely perfect rectangles. When you have North, South, East, and West boundary lengths, the widely used field formula is:
This average-of-opposite-sides method is common for roughly rectangular Bangladesh and East India plots. For highly skewed or curved boundaries, use a licensed surveyor or the irregular plot calculator.
Example: N=52 ft, S=48 ft, E=35 ft, W=33 ft
Method 3: Triangle Plots (Heron’s Formula)
For three-sided land parcels with sides a, b, c:
Example: sides 40 ft, 35 ft, 30 ft
Run the same inputs in the triangle land calculator to get Katha, Bigha, and Acre instantly.
Measuring in Hat, Gaz, Meter or Inch
Side lengths are often recorded in traditional or mixed units:
| Length Unit | Equals in Feet |
|---|---|
| 1 Inch | 1/12 ft (0.0833 ft) |
| 1 Hat (Cubit) | 1.5 ft |
| 1 Gaz (Yard) | 3 ft |
| 1 Meter | ≈ 3.28084 ft |
Convert every side to Feet before multiplying. Mixing Hat and Feet without conversion is a common source of deed vs field mismatch. The land area calculator accepts Feet, Hat, Gaz, Meter, or Inch per side independently.
Example: Length 20 Hat × Width 30 ft
Sq Ft to Common Land Units (Quick Bridge Table)
| Sq Ft | Decimal | Katha (720) | Bigha (14,400) | Acre |
|---|---|---|---|---|
| 435.6 | 1 | 0.605 | 0.030 | 0.01 |
| 720 | 1.65 | 1 | 0.05 | 0.017 |
| 1,000 | 2.30 | 1.39 | 0.069 | 0.023 |
| 14,400 | 33.06 | 20 | 1 | 0.331 |
| 43,560 | 100 | 60.5 | 3.025 | 1 |
For Katha ↔ Decimal step-by-steps, see Katha to Decimal & Square Feet. For Assam-specific ladders (Lessa/Katha), use the Assam land guide — Assam Katha is 2,880 Sq Ft, not 720.
Step-by-Step: Online Land Measurement from Dimensions
Common Mistakes That Inflate or Shrink Area
Frequently Asked Questions
How do I calculate Decimal from length and width?
Multiply length × width to get Square Feet, then divide by 435.6. Example: 50 × 40 = 2,000 Sq Ft ÷ 435.6 ≈ 4.59 Decimal.
What formula is used for four-sided irregular land?
Average opposite sides: Area = ((North + South) / 2) × ((East + West) / 2). Use a surveyor for highly irregular shapes.
How many Square Feet is 1 Decimal / Shotok?
1 Decimal = 435.6 Sq Ft, which is exactly 1/100 of an Acre.
Can I enter sides in Hat (হাত) instead of Feet?
Yes. 1 Hat = 1.5 Feet. Convert first, or use a calculator that accepts Hat / Gaz / Meter / Inch directly.
Which tool should I use for a triangular plot?
Use Heron’s formula or the triangle land plot calculator with all three side lengths.
Is length × width accurate enough for registry?
It is fine for rectangular plots and preliminary negotiations. Legal registration should follow an official survey plan and local revenue standards.