Land Area Calculation Formulas: Complete Guide

When purchasing or selling land or out of curiosity about a piece of land, the first question we ask is about the land's quantity, i.e., its area. In English, it is called Area. The most important aspect of measuring land is determining its length and width. By multiplying length and width, we get the land area.

Traditionally in Bangladesh, Kolkata, Assam, Odisha, Bihar, and many provinces of India, land is measured in acres and decimals. Naturally, land comes in various shapes - quadrilateral, rectangular, square, triangular, or circular.

Methods for Calculating Land Area

1. Formula for Calculating Quadrilateral Land Area

The four boundaries of land can be identified as North, South, East, and West.

Formula:

Average Length = (North boundary length + South boundary length) / 2
Average Width = (East boundary length + West boundary length) / 2

Land Area = Length × Width = Square unit

Example

A four-sided land plot has a North boundary of 80 feet 6 inches, South boundary of 87 feet, East boundary of 25 feet 8 inches, and West boundary of 28 feet 4 inches. What is the land area?

Solution:

According to the question,

• North boundary length = 80 feet 6 inches = 80 feet + 6/12 feet = 80 feet + 0.5 feet = 80.5 feet
• South boundary length = 87 feet
• East boundary length = 25 feet 8 inches = 25 feet + 8/12 feet = 25 feet + 0.67 feet = 25.67 feet
• West boundary length = 28 feet 4 inches = 28 feet + 4/12 feet = 28 feet + 0.33 feet = 28.33 feet

Remember: 1 foot = 12 inches. To convert inches to feet, divide by 12

Calculation:

North-South average length = (80.5 feet + 87 feet)/2 = 83.75 feet

East-West average length = (25.67 feet + 28.33 feet)/2 = 27 feet

Land area = North-South average length × East-West average length

= 83.75 feet × 27 feet

= 2,261.25 square feet

Conversion:

In Decimal = (2,261.25 ÷ 435.60) = 5.19 Decimal

Remember: 1 Decimal = 435.60 square feet. To convert square feet to decimal, divide by 435.60

In Katha = (2,261.25 ÷ 720) = 3.14 Katha

Remember: 1 Katha = 720 square feet. To convert square feet to katha, divide by 720

Use our land measurement calculator to measure any four-sided land with any length and width.

2. Formula for Calculating Triangular Land Area

For three-sided land plots, you need to use the triangle area formula.

Example

A land plot with three unequal sides measuring 58 feet 11 inches, 72 feet 7 inches, and 84 feet 5 inches. What is the land area?

Solution:

According to the question,

• First side a = 58 feet 11 inches = 58 + 11/12 = 58.92 feet
• Second side b = 72 feet 7 inches = 72 + 7/12 = 72.58 feet
• Third side c = 84 feet 5 inches = 84 + 5/12 = 84.42 feet

Semi-perimeter s = (a + b + c) / 2 = (58.92 + 72.58 + 84.42) / 2 = 215.92 / 2 = 107.96

Heron's Formula:

Land Area = √(s(s - a)(s - b)(s - c))

Calculation:

Area = √(107.96(107.96 - 58.92)(107.96 - 72.58)(107.96 - 84.42))

= √(107.96 × 49.04 × 35.38 × 23.54)

= √4409380.9805197 (calculate square root using calculator)

= 2099.85 square feet

Conversion:

In Decimal = (2099.85 ÷ 435.60) = 4.82 Decimal

In Katha = (2099.85 ÷ 720) = 2.92 Katha (approx.)

Use our land measurement calculator to measure any three-sided land plot.

3. Formula for Calculating Circular Land Area

For circular or round land plots, you need to use the circle area formula.

Example

A circular land plot has a diameter of 58 feet 9 inches. What is the land area?

Solution:

To determine the area of a circular plot in the field, first, we need to measure the largest diameter with a measuring tape. You may ask how to find the largest diameter? In this case, hold one end of the tape at any point on the circumference of the circular land and rotate the other end around the circle until you get the largest length. This largest length is the diameter of the land.

Here, 58 feet 9 inches = 58 + 9/12 = 58 + 0.75 = 58.75 feet

Radius = Diameter/2 = 58.75/2 = 29.375 feet

Circle Area Formula:

Area = πr²

Where π (pi) = 3.14159 and r is the radius = half of the diameter

Calculation:

Area = 3.14159 × (29.375)²

= 3.14159 × 29.375 × 29.375

= 2,710.85 square feet (approx.)

Conversion:

In Decimal = (2,710.85 ÷ 435.6) = 6.22 Decimal

In Katha = (2,710.85 ÷ 720) = 3.77 Katha (approx.)

Use our land measurement calculator to measure circular or round land plots.

Important Conversion Formulas

Land Measurement Tips

1. Take Accurate Measurements: Always keep the tape or measuring tool straight
2. Double Check: Measure again after the first measurement to confirm
3. Mark Boundaries: Clearly mark the four corners of the land
4. Use Calculator: For complex calculations, use our calculator
5. Professional Help: For large plots, hire a licensed surveyor

Conclusion

Accurately calculating land area is crucial for land buying, selling, and development planning. By following this guide, you can easily determine the area of lands with different shapes. For easier and faster calculations, use our land measurement calculator.