1. Length Conversions
| From | To mm | To cm | To m | To km | To inch | To feet | To yard |
|---|
| 1 mm | 1 | 0.1 | 0.001 | 0.000001 | 0.03937 | 0.003281 | 0.001094 |
| 1 cm | 10 | 1 | 0.01 | 0.00001 | 0.3937 | 0.03281 | 0.01094 |
| 1 m | 1000 | 100 | 1 | 0.001 | 39.37 | 3.281 | 1.094 |
| 1 km | 1,000,000 | 100,000 | 1000 | 1 | 39,370 | 3281 | 1094 |
| 1 inch | 25.4 | 2.54 | 0.0254 | — | 1 | 0.0833 | 0.02778 |
| 1 foot | 304.8 | 30.48 | 0.3048 | 0.0003048 | 12 | 1 | 0.3333 |
| 1 yard | 914.4 | 91.44 | 0.9144 | 0.0009144 | 36 | 3 | 1 |
| 1 mile | 1,609,344 | 160,934 | 1609.34 | 1.60934 | 63,360 | 5280 | 1760 |
| 1 furlong | 201,168 | 20,116.8 | 201.168 | 0.201168 | 7920 | 660 | 220 |
| 1 nautical mile | 1,852,000 | 185,200 | 1852 | 1.852 | 72,913 | 6076.1 | 2025.4 |
Quick Recall: 1 ft = 0.3048 m | 1 inch = 25.4 mm | 1 mile = 1.609 km | 1 m = 3.281 ft = 39.37 inches
2. Area Conversions
| Unit | In m² | In ft² | In cm² |
|---|
| 1 mm² | 0.000001 | 0.0000108 | 0.01 |
| 1 cm² | 0.0001 | 0.001076 | 1 |
| 1 m² | 1 | 10.764 | 10,000 |
| 1 km² | 1,000,000 | 10,763,910 | 10¹⁰ |
| 1 ft² | 0.0929 | 1 | 929.03 |
| 1 yard² | 0.8361 | 9 | 8361 |
| 1 acre | 4046.86 | 43,560 | 40,468,600 |
| 1 hectare | 10,000 | 107,639 | 100,000,000 |
| 1 sq mile | 2,589,988 | 27,878,400 | — |
Quick Recall: 1 hectare = 10,000 m² = 2.47 acres | 1 acre = 4047 m² | 1 km² = 100 hectares = 247 acres
3. Volume Conversions
| Unit | In m³ | In litres | In ft³ |
|---|
| 1 litre (L) | 0.001 | 1 | 0.03531 |
| 1 mL | 0.000001 | 0.001 | 0.0000353 |
| 1 m³ | 1 | 1000 | 35.315 |
| 1 cm³ | 0.000001 | 0.001 | 0.0000353 |
| 1 ft³ | 0.02832 | 28.32 | 1 |
| 1 yard³ | 0.7646 | 764.6 | 27 |
| 1 gallon (US) | 0.003785 | 3.785 | 0.1337 |
| 1 gallon (Imperial/UK) | 0.004546 | 4.546 | 0.1605 |
| 1 cubic inch | 0.00001639 | 0.01639 | 0.000579 |
Quick Recall: 1 m³ = 1000 litres = 35.31 ft³ | 1 ft³ = 28.32 litres | 1 cusec = 1 ft³/s = 28.32 litres/s
4. Mass / Weight Conversions
| Unit | In kg | In grams | In lb | In tonnes (metric) |
|---|
| 1 gram (g) | 0.001 | 1 | 0.002205 | 0.000001 |
| 1 kilogram (kg) | 1 | 1000 | 2.2046 | 0.001 |
| 1 tonne (metric, MT) | 1000 | 1,000,000 | 2204.6 | 1 |
| 1 quintal | 100 | 100,000 | 220.46 | 0.1 |
| 1 pound (lb) | 0.4536 | 453.6 | 1 | 0.0004536 |
| 1 ounce (oz) | 0.02835 | 28.35 | 0.0625 | 0.00002835 |
| 1 ton (UK/long ton) | 1016.05 | 1,016,050 | 2240 | 1.016 |
| 1 ton (US/short ton) | 907.18 | 907,185 | 2000 | 0.9072 |
5. Force Conversions
| Unit | In N | In kN | In kgf | In lbf | In kips |
|---|
| 1 N | 1 | 0.001 | 0.10197 | 0.2248 | 0.0002248 |
| 1 kN | 1000 | 1 | 101.97 | 224.8 | 0.2248 |
| 1 MN | 1,000,000 | 1000 | 101,971 | 224,809 | 224.81 |
| 1 kgf | 9.807 | 0.009807 | 1 | 2.2046 | 0.002205 |
| 1 tf (tonne-force) | 9807 | 9.807 | 1000 | 2204.6 | 2.2046 |
| 1 lbf | 4.448 | 0.004448 | 0.4536 | 1 | 0.001 |
| 1 kip (1000 lbf) | 4448 | 4.448 | 453.6 | 1000 | 1 |
6. Stress / Pressure Conversions
| Unit | In Pa (N/m²) | In kPa | In MPa (N/mm²) | In kg/cm² | In psi | In bar |
|---|
| 1 Pa | 1 | 0.001 | 0.000001 | 0.0000102 | 0.000145 | 0.00001 |
| 1 kPa | 1000 | 1 | 0.001 | 0.010197 | 0.14504 | 0.01 |
| 1 MPa = 1 N/mm² | 1,000,000 | 1000 | 1 | 10.197 | 145.04 | 10 |
| 1 kg/cm² | 98,066 | 98.066 | 0.09807 | 1 | 14.22 | 0.9807 |
| 1 kN/m² | 1000 | 1 | 0.001 | 0.010197 | 0.14504 | 0.01 |
| 1 psi | 6894.8 | 6.895 | 0.006895 | 0.07031 | 1 | 0.06895 |
| 1 ksi | 6,894,800 | 6895 | 6.895 | 70.31 | 1000 | 68.95 |
| 1 bar | 100,000 | 100 | 0.1 | 1.0197 | 14.504 | 1 |
| 1 atm | 101,325 | 101.325 | 0.10133 | 1.0332 | 14.696 | 1.01325 |
Key Equivalence: 1 MPa = 1 N/mm² = 10.2 kg/cm² | 1 kg/cm² ≈ 0.1 MPa | 1 bar ≈ 100 kPa
7. Flow Rate Conversions
| Unit | m³/s | litres/s | litres/min | m³/hr | cusec (ft³/s) |
|---|
| 1 m³/s | 1 | 1000 | 60,000 | 3600 | 35.315 |
| 1 litre/s | 0.001 | 1 | 60 | 3.6 | 0.03531 |
| 1 litre/min | 0.0000167 | 0.01667 | 1 | 0.06 | 0.000589 |
| 1 m³/hr | 0.0002778 | 0.2778 | 16.667 | 1 | 0.009810 |
| 1 cusec (ft³/s) | 0.02832 | 28.32 | 1699 | 101.94 | 1 |
| 1 MGD (million gal/day) | 0.04381 | 43.81 | 2628 | 157.72 | 1.547 |
| 1 MLD (million lit/day) | 0.01157 | 11.574 | 694.4 | 41.67 | 0.4088 |
8. Speed Conversions
| Unit | m/s | km/hr | ft/s | mph |
|---|
| 1 m/s | 1 | 3.6 | 3.281 | 2.237 |
| 1 km/hr | 0.2778 | 1 | 0.9113 | 0.6214 |
| 1 ft/s | 0.3048 | 1.0973 | 1 | 0.6818 |
| 1 mph | 0.4470 | 1.6093 | 1.4667 | 1 |
9. Temperature Conversions
°F = (°C × 9/5) + 32 °C = (°F - 32) × 5/9 K = °C + 273.15
| °C | °F | K | Application |
|---|
| 0 | 32 | 273.15 | Freezing point of water |
| 5 | 41 | 278.15 | Minimum concrete curing temp |
| 27 | 80.6 | 300.15 | Typical Indian ambient |
| 38 | 100.4 | 311.15 | Max concrete mixing temp |
| 100 | 212 | 373.15 | Boiling point of water |
| 160 | 320 | 433.15 | Bitumen laying temperature |
10. Important Civil Engineering Constants & Approximations
| Constant / Quantity | Value | Remarks |
|---|
| g (acceleration due to gravity) | 9.81 m/s² (use 10 for approx.) | Standard: 9.806 m/s² |
| Density of water | 1000 kg/m³ = 1 g/cm³ | At 4°C |
| Density of concrete (PCC) | 2400 kg/m³ | |
| Density of reinforced concrete (RCC) | 2500 kg/m³ | |
| Density of brick masonry | 1800 – 1900 kg/m³ | |
| Density of dry soil | 1600 – 1800 kg/m³ | |
| Density of saturated soil | 1900 – 2100 kg/m³ | |
| Density of steel | 7850 kg/m³ | |
| Density of bitumen | 1000 – 1050 kg/m³ | |
| E for mild steel | 200 GPa = 2 × 10⁵ MPa | |
| E for concrete M25 | 5000√25 = 25,000 MPa | IS 456:2000 |
| Specific weight of water (γw) | 9.81 kN/m³ ≈ 10 kN/m³ | |
| π (pi) | 3.14159265 | |
| 1 radian | 57.296° | |