# Unit Conversion Tables Quick-reference conversion tables for the practicing architect and building engineer. These tables cover the most commonly encountered unit conversions in architectural design, structural engineering, and building services. --- ## Table of Contents - [Length](#length) - [Area](#area) - [Volume](#volume) - [Mass and Weight](#mass-and-weight) - [Force](#force) - [Pressure and Stress](#pressure-and-stress) - [Moment and Torque](#moment-and-torque) - [Temperature](#temperature) - [Thermal Properties](#thermal-properties) - [Illumination](#illumination) - [Sound](#sound) - [Velocity](#velocity) - [Common Architectural Conversions](#common-architectural-conversions) --- ## Length | From | To | Multiply by | |------|----|-------------| | mm | inches | 0.03937 | | mm | feet | 0.003281 | | m | feet | 3.281 | | m | yards | 1.094 | | km | miles | 0.6214 | | inches | mm | 25.40 | | feet | mm | 304.8 | | feet | m | 0.3048 | | yards | m | 0.9144 | | miles | km | 1.609 | **Quick references**: - 1 inch = 25.4 mm - 1 foot = 304.8 mm = 0.3048 m - 1 metre = 3 ft 3⅜ in (approximately 3'-3⅜") - 1 mile = 1.609 km --- ## Area | From | To | Multiply by | |------|----|-------------| | m² | ft² | 10.76 | | m² | acres | 0.0002471 | | hectare (ha) | acres | 2.471 | | hectare (ha) | m² | 10,000 | | ft² | m² | 0.09290 | | acres | m² | 4,047 | | acres | hectares | 0.4047 | | km² | square miles | 0.3861 | **Quick references**: - 1 m² = 10.76 ft² - 1 hectare = 10,000 m² = 2.471 acres - 1 acre = 4,047 m² = 0.4047 hectares - 1 ft² = 0.0929 m² --- ## Volume | From | To | Multiply by | |------|----|-------------| | m³ | ft³ | 35.31 | | m³ | litres | 1,000 | | m³ | US gallons | 264.2 | | m³ | Imperial gallons | 220.0 | | litres | US gallons | 0.2642 | | litres | Imperial gallons | 0.2200 | | litres | ft³ | 0.03531 | | ft³ | m³ | 0.02832 | | ft³ | litres | 28.32 | | US gallons | litres | 3.785 | | Imperial gallons | litres | 4.546 | **Quick references**: - 1 m³ = 1,000 litres - 1 Imperial gallon = 4.546 litres - 1 US gallon = 3.785 litres - 1 ft³ = 28.32 litres --- ## Mass and Weight | From | To | Multiply by | |------|----|-------------| | kg | lb (pounds) | 2.205 | | kg | short tons (US) | 0.001102 | | tonne (metric) | kg | 1,000 | | tonne (metric) | long tons (UK) | 0.9842 | | tonne (metric) | short tons (US) | 1.102 | | lb | kg | 0.4536 | | short ton (US) | kg | 907.2 | | long ton (UK) | kg | 1,016 | **Quick references**: - 1 kg = 2.205 lb - 1 tonne = 1,000 kg = 2,205 lb - 1 lb = 0.4536 kg --- ## Force | From | To | Multiply by | |------|----|-------------| | N (Newton) | kgf | 0.1020 | | N | lbf | 0.2248 | | kN | kgf | 101.97 | | kN | kip (1000 lbf) | 0.2248 | | kgf | N | 9.807 | | lbf | N | 4.448 | | kip | kN | 4.448 | **Quick references**: - 1 kN = approximately 100 kgf = 224.8 lbf - 1 kgf = 9.807 N - 1 kip = 4.448 kN --- ## Pressure and Stress | From | To | Multiply by | |------|----|-------------| | kPa | psi | 0.1450 | | kPa | kgf/cm² | 0.01020 | | kPa | bar | 0.01 | | MPa | N/mm² | 1.0 (identical) | | MPa | psi | 145.0 | | MPa | kgf/cm² | 10.20 | | bar | kPa | 100 | | psi | kPa | 6.895 | | psi | MPa | 0.006895 | | kgf/cm² | kPa | 98.07 | | atm | kPa | 101.3 | **Quick references**: - 1 MPa = 1 N/mm² = 145 psi = 10.2 kgf/cm² - 1 bar = 100 kPa = 14.5 psi - 1 atm = 101.3 kPa - Structural concrete: 30 MPa = 30 N/mm² = 4,350 psi --- ## Moment and Torque | From | To | Multiply by | |------|----|-------------| | kNm | kip-ft | 0.7376 | | kNm | kgf-m | 101.97 | | kNm | lbf-ft | 737.6 | | kip-ft | kNm | 1.356 | | kgf-m | kNm | 0.009807 | --- ## Temperature | Conversion | Formula | |-----------|---------| | °C to °F | °F = (°C × 9/5) + 32 | | °F to °C | °C = (°F - 32) × 5/9 | | °C to K (Kelvin) | K = °C + 273.15 | **Quick references**: | °C | °F | Context | |----|----|---------| | -18 | 0 | Cold storage | | 0 | 32 | Water freezes | | 20 | 68 | Standard room temperature | | 22 | 72 | Typical office thermostat | | 37 | 98.6 | Human body temperature | | 100 | 212 | Water boils | | 550 | 1022 | Steel loses ~50% strength | --- ## Thermal Properties | From | To | Multiply by | |------|----|-------------| | W/mK | BTU·in/(hr·ft²·°F) | 6.933 | | W/m²K (U-value) | BTU/(hr·ft²·°F) | 0.1761 | | m²K/W (R-value metric) | ft²·°F·hr/BTU (R-value US) | 5.678 | | BTU/(hr·ft²·°F) | W/m²K | 5.678 | **Quick references**: - U-value 0.15 W/m²K = R-value 38 (US) = R-value 6.67 (metric) - U-value 1.0 W/m²K = R-value 5.68 (US) = R-value 1.0 (metric) - R-value (US) = 5.678 × R-value (metric) **Common insulation lambda values**: | Material | λ (W/mK) | |----------|----------| | PIR board | 0.022-0.028 | | Phenolic foam | 0.020-0.022 | | XPS | 0.029-0.036 | | EPS | 0.032-0.038 | | Mineral wool | 0.032-0.040 | | Aerogel | 0.013-0.015 | --- ## Illumination | From | To | Multiply by | |------|----|-------------| | lux (lx) | foot-candles (fc) | 0.09290 | | foot-candles | lux | 10.76 | **Typical illumination levels**: | Space | Lux | Foot-candles | |-------|-----|--------------| | Corridor/circulation | 100 | 9.3 | | Office — general | 300-500 | 28-46 | | Detailed drawing work | 750 | 70 | | Operating theatre (general) | 1,000 | 93 | | Surgical field (luminaire) | 40,000-160,000 | 3,700-14,900 | | Residential — living room | 150-300 | 14-28 | | Museum — sensitive materials | 50 | 4.6 | | Museum — paintings | 150-200 | 14-19 | | Emergency lighting | 1 (minimum) | 0.09 | --- ## Sound | Metric | Description | Notes | |--------|-------------|-------| | dB (SPL) | Sound pressure level | Logarithmic scale; +3 dB = double intensity; +10 dB = perceived doubling | | dBA | A-weighted SPL | Approximates human hearing sensitivity | | STC | Sound Transmission Class | Single-number rating for airborne sound insulation (US) | | Rw | Weighted Sound Reduction Index | Single-number rating for airborne sound insulation (ISO) | **Approximate equivalence**: STC ≈ Rw + 1 to 3 (varies by spectrum) **Reference noise levels**: | Source | dBA | |--------|-----| | Threshold of hearing | 0 | | Rural ambient | 20-30 | | Quiet office | 35-40 | | Normal conversation (1m) | 60 | | Busy road at 10m | 70-80 | | Construction site | 85-95 | | Threshold of pain | 120-130 | --- ## Velocity | From | To | Multiply by | |------|----|-------------| | m/s | km/h | 3.6 | | m/s | mph | 2.237 | | m/s | ft/s | 3.281 | | km/h | m/s | 0.2778 | | mph | m/s | 0.4470 | | knots | m/s | 0.5144 | **Wind speed references**: See [[Wind Engineering for Buildings]] for design wind speeds. --- ## Common Architectural Conversions | Imperial | Metric (exact) | Context | |----------|---------------|---------| | 8'-0" (2,438mm) | 2,440mm (standard) | Ceiling height / sheet goods | | 4' × 8' sheet | 1,220 × 2,440mm | Plywood, plasterboard | | 2 × 4 stud | 38 × 89mm (actual) | Timber framing | | 2 × 6 stud | 38 × 140mm (actual) | Timber framing | | 4" block | 100mm block | Masonry | | 6" block | 150mm block | Masonry | | 8" block | 200mm block | Masonry | --- ## See Also - [[Material Weight Tables]] - [[Occupancy Load Tables]] - [[Illumination Level Standards]] - [[Ventilation Rate Tables]] - [[Sound Insulation Requirements]] --- #reference #conversion #units #tables