Loading Calculator...
Please wait a moment
Please wait a moment
Convert pounds per cubic foot to kilograms per cubic meter (lb ft3 to kg m3) instantly. Bidirectional density conversion with formula, material density tables, and step-by-step worked examples for engineering and construction.
1 lb/ft³ = 16.0185 kg/m³
The core conversion factor
Water = 62.43 lb/ft³
Equals exactly 1000 kg/m³
Factor = 0.4536 / 0.02832
Mass ratio divided by volume ratio
Formula: kg/m³ = lb/ft³ × 16.0185 | lb/ft³ = kg/m³ ÷ 16.0185
Reference table converting common lb/ft³ values to kg/m³. All values are calculated using the factor 16.0185 and rounded to one decimal place.
| lb/ft³ | kg/m³ | lb/ft³ | kg/m³ |
|---|---|---|---|
| 1 | 16 | 60 | 961.1 |
| 2 | 32 | 62.43 | 1000 |
| 5 | 80.1 | 70 | 1121.3 |
| 10 | 160.2 | 80 | 1281.5 |
| 15 | 240.3 | 90 | 1441.7 |
| 20 | 320.4 | 100 | 1601.9 |
| 25 | 400.5 | 120 | 1922.2 |
| 30 | 480.6 | 140 | 2242.6 |
| 35 | 560.6 | 150 | 2402.8 |
| 40 | 640.7 | 160 | 2562.9 |
| 45 | 720.8 | 175 | 2803.2 |
| 50 | 800.9 | 200 | 3203.7 |
Real-world material densities for engineering, construction, and science. Values are typical at standard room temperature. Actual density may vary based on alloy, grade, moisture, and temperature.
| Material | lb/ft³ | kg/m³ | Common Use |
|---|---|---|---|
| Air (sea level) | 0.075 | 1.2 | HVAC calculations |
| Styrofoam | 1.9 | 30 | Insulation, packaging |
| Pine wood | 31 | 497 | Framing, furniture |
| Oak wood | 45 | 721 | Flooring, cabinetry |
| Water (4°C) | 62.43 | 1,000 | Reference standard |
| Seawater | 64.0 | 1,025 | Marine engineering |
| Concrete (normal) | 150 | 2,400 | Foundations, slabs |
| Glass | 156 | 2,500 | Windows, containers |
| Aluminum | 169 | 2,710 | Aircraft, cans |
| Granite | 165 | 2,640 | Countertops, monuments |
| Steel (carbon) | 490 | 7,850 | Structural beams |
| Stainless steel | 500 | 8,000 | Kitchen, medical |
| Copper | 559 | 8,960 | Wiring, plumbing |
| Lead | 708 | 11,340 | Radiation shielding |
| Gold | 1,205 | 19,300 | Jewelry, electronics |
Density is a fundamental physical property defined as mass per unit volume, expressed mathematically as ρ = m / V. It measures how tightly matter is packed within a given space. Every material has a characteristic density that serves as an identifying fingerprint in engineering, manufacturing, and scientific analysis. Density is an intensive property, meaning it does not change with sample size — a small block of steel has the same density as a massive steel beam.
In imperial units, density is commonly expressed as pounds per cubic foot (lb/ft³), which is the standard in US construction, HVAC design, and civil engineering. The metric system uses kilograms per cubic meter (kg/m³) as the SI standard for density. While both measure the same physical property, the numerical values differ significantly due to the different sizes of the units involved. Water, for instance, measures 62.43 lb/ft³ in imperial but a neat 1,000 kg/m³ in metric.
The conversion between lb/ft³ and kg/m³ arises frequently in international engineering projects, material science research, and any context where imperial and metric specifications must be reconciled. Understanding how to convert between these density units — and why the conversion factor is 16.0185 — is a practical skill for engineers, architects, geologists, and anyone working with material properties across different measurement systems.
Historically, density measurements have been central to materials science since Archimedes reportedly used density to detect a forged gold crown over two thousand years ago. Today, density testing is standard practice for quality control in manufacturing, soil compaction verification in geotechnical work, and material identification in forensic and environmental laboratories.
The factor 16.0185 = 0.453592 kg/lb ÷ 0.0283168 m³/ft³
For a quick estimate, multiply lb/ft³ by 16. This gives you a result within 0.1% of the exact answer and is easy to calculate mentally. For example, 100 lb/ft³ is approximately 1,600 kg/m³ (exact: 1,601.9 kg/m³). For even faster estimation, note that 1 lb/ft³ is roughly 16 kg/m³.
This matches the standard metric value for concrete used in international building codes.
The standard reference density for aluminum is 2,710 kg/m³. The small difference comes from rounding the starting value.
Geotechnical engineers frequently convert between units when referencing international soil classification standards.
The accepted value for copper is 8,960 kg/m³. Plumbing and electrical engineers use this when calculating pipe and cable weights.
Accurate density values are essential for calculating dead loads, material weights, and structural capacity. A 5% error in density translates directly to a 5% error in weight calculations, potentially compromising safety factors in building design.
Material specifications shipped globally use metric units (kg/m³), while US construction uses imperial (lb/ft³). Accurate conversion ensures materials meet project requirements when sourcing from international suppliers or following overseas standards.
Measured density compared to expected density reveals manufacturing defects, porosity, contamination, or incorrect material composition. Converting between units allows comparison against reference databases published in either measurement system.
Soil compaction tests report density in lb/ft³ (US) or kg/m³ (international). Converting between units allows comparison with specifications from different standards bodies such as ASTM (imperial) and ISO (metric).
Make sure you are converting lb/ft³, not lb/in³ or lb/gal. Confusing these units produces wildly incorrect results. One lb/in³ equals 1,728 lb/ft³, so the difference is enormous.
Rounding to 16 introduces a 0.12% error. While acceptable for estimates, use 16.0185 for engineering calculations where precision matters.
Loose materials like gravel or powder have air gaps that reduce bulk density. A bag of sand at 100 lb/ft³ bulk density does not mean each grain has that density. Solid quartz sand is actually about 165 lb/ft³.
Density changes with temperature. Most materials expand when heated, reducing their density. For liquids and gases, always note the temperature at which density was measured. Air density at 100°F is about 5% less than at 70°F.
When converting lb/ft³ to kg/m³, multiply by 16.0185. When converting kg/m³ to lb/ft³, divide by 16.0185. Mixing up the direction is the most common conversion error and gives results off by a factor of 256.
The conversion factor is 16.0185. To convert pounds per cubic foot to kilograms per cubic meter, multiply the lb/ft³ value by 16.0185. This factor is derived from dividing the pound-to-kilogram ratio (0.453592) by the cubic-foot-to-cubic-meter ratio (0.0283168), giving 0.453592 / 0.0283168 = 16.0185.
To convert kg/m³ to lb/ft³, divide the kg/m³ value by 16.0185. For example, water has a density of 1000 kg/m³. Dividing 1000 by 16.0185 gives approximately 62.43 lb/ft³. You can also multiply by the reciprocal factor 0.062428.
Water at 4 degrees Celsius has a density of 62.43 lb/ft³ or 1000 kg/m³. This is a convenient reference point because water at peak density equals exactly 1000 kg/m³ in metric units. Temperature affects water density slightly: at 20 degrees Celsius it drops to about 62.32 lb/ft³ (998.2 kg/m³).
The factor 16.0185 combines two unit conversions. One pound equals 0.453592 kilograms, and one cubic foot equals 0.0283168 cubic meters. Since density is mass divided by volume, you divide the mass conversion by the volume conversion: 0.453592 / 0.0283168 = 16.0185. This single multiplication handles both the mass and volume unit changes simultaneously.
Steel has a density of approximately 490 lb/ft³ or 7850 kg/m³. This can vary slightly depending on the alloy: carbon steel is about 490 lb/ft³ (7850 kg/m³), stainless steel ranges from 487 to 503 lb/ft³ (7800 to 8060 kg/m³), and tool steel is about 487 lb/ft³ (7800 kg/m³). These values are critical for structural engineering calculations.
Normal-weight concrete has a density of about 145 to 150 lb/ft³ (2320 to 2400 kg/m³). Lightweight structural concrete ranges from 90 to 115 lb/ft³ (1440 to 1840 kg/m³). Heavyweight concrete used for radiation shielding can reach 250 lb/ft³ (4000 kg/m³) or more. The exact density depends on the aggregate type and mix design.
This conversion is commonly needed when working with international engineering specifications, importing or exporting building materials, comparing material data sheets from different countries, performing structural calculations for projects that mix imperial and metric standards, and when scientific papers report density in SI units but you work in imperial. Construction, HVAC, and geotechnical engineering frequently require this conversion.
Temperature does not affect the conversion factor itself, which is always 16.0185. However, temperature does affect the actual density of materials. Most substances expand when heated, reducing their density. For example, water is 62.43 lb/ft³ at 4 degrees Celsius but only 59.83 lb/ft³ at 100 degrees Celsius. Always note the temperature when comparing density values.
To convert lb/ft³ to g/cm³ (grams per cubic centimeter), multiply by 0.016018. This is because 1 kg/m³ equals 0.001 g/cm³, so the factor is 16.0185 times 0.001 = 0.016018. For example, steel at 490 lb/ft³ equals 490 times 0.016018 = 7.85 g/cm³. The g/cm³ unit is commonly used in chemistry and materials science.
True density (or absolute density) measures the mass of a solid material per unit volume, excluding any air voids. Bulk density includes the air spaces between particles. For example, solid steel has a true density of 490 lb/ft³ (7850 kg/m³), but loose steel shot might have a bulk density of only 280 lb/ft³ (4485 kg/m³) due to air gaps. Always specify which density type you are using when converting units.
This calculator is provided for informational and educational purposes only. Always verify critical engineering calculations with a qualified professional. UnitTables.com is not responsible for errors or consequences arising from the use of this tool.