Unit conversions are a crucial aspect of civil engineering, and without accurate measurements, it is impossible to complete any construction project.
Units of measurement are defined as magnitudes of quantities that serve as standards for comparing quantities of similar magnitudes, such as length, weight, and volume.
This article contains some basic unit conversion factors most commonly used in civil engineering; hopefully, it will be helpful!
Unit Measurement & Conversion Factors in Civil Engineering:
Length:
Length is a single-axis (X-axis only) measurement that measures a straight profile.
The following units are used: millimeters (mm), meters (m), kilometers (km), feet (ft), inches (in), etc.
Area:
Area is a two-axis {X & Y axis} measurement that measures a shape profile.
The following units are used: millimeter square (mm2), meter (m2), kilometer (km2), feet (ft2), inch (in2), etc.
Volume:
Volume is a three-axis (X, Y, and Z) measurement that measures a shape profile with height, thickness, and depth.
The following units are used: cubic inch (in3), cubic feet (ft3), cubic meters (m3), cubic millimeters (mm3), etc.
Classification of Units in Surveying:
There are historically two survey measurement systems:
Metric system:
The metric system was brought to India by the Weights and Measures Act 1956; it is commonly adopted in the global world.
Metric units are developed using powers of 10; these are units of length, area, and volume.
It became the official system in France in 1795 and later spread throughout the world.
It contains units like millimetre, centimetre, metre, and kilometre.
Foot-Pound-Second (FPS) or Imperial System:
The British Imperial system is also called the FPS system; this system was widely used in India till 1956.
In the United States, Liberia, and Myanmar, the imperial system is still widely active in land and property surveys.
It relies on the older British systems of measurement.
It is not decimal-based, and thus conversions can be more complex.
It contains units like inches, feet, yards, and acres.
Basic Unit Conversions:
Length Conversions:
| Unit | Equivalent Values |
| 1 meter (m) | 100 cm = 1000 mm = 3.281 ft = 1.09361 |
| 1 foot (ft) | 12 inches = 0.3048 m |
| 1 inch (in) | 25.4 mm = 2.54 cm = 8 Soot |
| 1 yard (yd) | 3 ft = 0.9144 m |
| 1 kilometer (km) | 1000 m = 3280.84 ft = 0.6214 miles =1093.6133 yards |
| 1 mile | 1609m = 5280 ft = 1.609 km |
Area Conversions:
| Unit | Equivalent Values |
| 1 square meter (m²) | 10.764 ft² = 1.196 yd² |
| 1 square foot (ft²) | 144 in² = 0.0929 m² |
| 1 square yard (yd²) | 9 ft² = 0.8361 m² |
| 1 ground | 2400 ft² |
| 1 cent | 40.5 m² |
| 1 cent | 435.6 ft² |
| 1 cent | 5.5 ground |
| 1 cent | 100 acres |
| 1 acre | 4046.86 m² = 43560 ft² = 0.4 Hectares |
| 1 hectare (ha) | 10000 m² = 2.471 acres |
Volume Conversions:
| Unit | Equivalent Values |
| 1 cubic meter (m³) | 1000 liters (L) = 35.315 ft³ |
| 1 cubic foot (ft³) | 28.316 L = 0.0283 m³ |
| 1 cubic inch (in³) | 16.387 cm³ = 0.000016 m³ |
| 1 gallon (US) | 3.785 L |
| 1 gallon (UK) | 4.546 L |
Weight & Mass Conversions:
| Unit | Equivalent Values |
| 1 kilogram (kg) | 1000 g = 2.2046 lb |
| 1 metric ton | 1000 kg = 2204.62 lb |
| 1 pound (lb) | 0.4536 kg = 16 ounces |
| 1 gram (g) | 1000 mg = 0.0353 oz |
Pressure Conversions:
| Unit | Equivalent Values |
| 1 pascal (Pa) | 1 N/m² |
| 1 kilopascal (kPa) | 1000 Pa = 0.145 psi |
| 1 megapascal (MPa) | 1000 kPa = 145 psi |
| 1 atmosphere (atm) | 101.325 kPa = 14.7 psi |
| 1 psi (pounds per square inch) | 6.895 kPa |
Force & Load Conversions:
| Unit | Equivalent Values |
| 1 Newton (N) | 0.10197 kgf = 0.2248 lbf |
| 1 kilonewton (kN) | 1000 N = 101.97 kgf = 224.8 lbf |
| 1 ton-force (tonf) | 9.81 kN |
Concrete & Reinforcement Conversions:
| Item | Equivalent Values |
| 1 bag of cement (50 kg) | 50kg = 0.035 m³ = 1.23 ft³ |
| 1 m³ of concrete | 2400 kg (varies based on mix) |
| 1 m³ of sand | 1600 kg |
| 1 m³ of aggregate | 1400 kg |
| Steel weight formula | Weight (kg) = (D²/162) × Length (m) |
Brick & Block Conversions:
| Item | Equivalent Values |
| 1 standard brick size (India) | 190 mm × 90 mm × 90 mm |
| 1 brick with mortar | 200 mm × 100 mm × 100 mm |
| 1 m³ of brick masonry | 500 bricks |
| 1 m³ of hollow blocks | 13.5 blocks |
Power & Energy Conversions:
| Unit | Equivalent Values |
| 1 watt (W) | 1 J/s = 0.00134 HP |
| 1 kilowatt (kW) | 1000 W = 1.341 HP |
| 1 horsepower (HP) | 745.7 W |
Basic Unit Conversions- Frequently Asked Questions:
What units do civil engineers use?
Depending on the region and the project’s specific goals, civil engineers use either the Imperial system (also known as the feet-pound-second system, or FPS), which employs feet and pounds, or the International System of Units (SI), which utilizes meters and kilograms.
What are the 7 main units of measurement?
The seven fundamental units of measurement are the metre (m) for length, the kilogram (kg) for mass, the second (s) for time, the ampere (A) for electric current, the kelvin (K) for thermodynamic temperature, the mole (mol) for material quantity, and the candela (cd) for luminous intensity.
What are the units of measurement in construction?
Four categories of measurement units are used in construction: volume for cubic measurements, area for surfaces (such as square meters and square feet), and length for linear measures (such as running meters and feet).
How many units are in civil engineering?
There is no specific number of civil engineering units.
Conclusion:
These are the fundamental unit conversions, while additional conversions are used daily.
Section Under: Measurements
