Density Calculator — Free Online Density Unit Converter

How to Use the Density Calculator

1. Enter the density value: Type the numeric density you want to convert into the Density Value field. You can enter whole numbers like 1000 or precise decimals like 7.874. The calculator handles values from very small densities (like gases at 0.001 kg/m3) to very large densities (like metals at 20,000+ kg/m3) with equal accuracy.
2. Select your input unit: Use the From Unit dropdown to choose the density unit of your input value. Choose from kilograms per cubic meter (kg/m3), grams per cubic centimeter (g/cm3), pounds per cubic foot (lb/ft3), pounds per cubic inch (lb/in3), or kilograms per liter (kg/L). Pick the unit that matches your source measurement.
3. Read all conversions simultaneously: The results panel on the right displays your density value converted to all four other supported units at once. This eliminates the need for multiple separate conversions and makes it easy to find the unit you need for any application, whether academic, industrial, or personal.
4. Adjust values in real time: Change the input value or source unit at any time and all results update instantly. This is useful for comparing densities of different materials, building reference tables, or checking homework answers against multiple unit systems.

The calculator displays results with up to six decimal places for scientific precision. For materials with known densities, entering the standard value and checking all unit conversions is a quick way to verify calculations in any unit system.

Density Conversion Formulas

Conversion Factors (from kg/m3)

Variables Explained

• kg/m3 (Kilograms per cubic meter): The SI standard unit for density. Water has a density of 1,000 kg/m3 at 4 degrees Celsius. This unit is used in physics, chemistry, and engineering worldwide for scientific calculations and technical specifications.
• g/cm3 (Grams per cubic centimeter): Equivalent to kg/L and numerically equal to specific gravity. Water has a density of 1.0 g/cm3. This unit is widely used in chemistry, geology, and materials science because most common materials fall in a convenient 0.5 to 22 range.
• lb/ft3 (Pounds per cubic foot): The standard density unit in US construction, civil engineering, and building materials. Concrete is approximately 150 lb/ft3, and wood ranges from 25 to 60 lb/ft3 depending on species. This unit is essential for structural load calculations in imperial units.
• lb/in3 (Pounds per cubic inch): Used in US mechanical engineering and manufacturing for small, dense components. Steel is approximately 0.284 lb/in3. This unit is practical when working with machined parts and components where dimensions are measured in inches.
• kg/L (Kilograms per liter): Numerically identical to g/cm3 because 1 liter equals 1,000 cm3. Water has a density of 1.0 kg/L. This unit is commonly used in chemistry and everyday contexts, especially for liquids and solutions.

Step-by-Step Example

Convert the density of steel (7,850 kg/m3) to all other units:

1. Start with steel density: 7,850 kg/m3
2. Convert to g/cm3: 7,850 / 1,000 = 7.850 g/cm3
3. Convert to lb/ft3: 7,850 / 16.0185 = 490.05 lb/ft3
4. Convert to lb/in3: 7,850 / 27,679.9 = 0.2836 lb/in3
5. Convert to kg/L: 7,850 / 1,000 = 7.850 kg/L

Steel at 7,850 kg/m3 is approximately 7.85 times denser than water. In imperial units, a cubic foot of steel weighs about 490 pounds, or about 0.284 pounds per cubic inch. These values are essential for structural engineering calculations, shipping weight estimates, and materials selection.

Practical Examples

Example 1: Mike's Concrete Estimation

Mike is a contractor pouring a concrete patio and needs to estimate the total weight for his delivery truck. The concrete supplier specifies a density of 150 lb/ft3, but the structural engineer's plans reference density in kg/m3. Mike uses the density calculator to reconcile the specifications:

• Input: 150 lb/ft3
• In kg/m3: 2,402.8 kg/m3
• Patio volume: 4m x 3m x 0.1m = 1.2 m3
• Total weight: 1.2 x 2,402.8 = 2,883 kg (6,355 lb)

Mike confirms the concrete density matches the engineer's specification of approximately 2,400 kg/m3. The total patio weight of about 2,883 kg (roughly 6,355 pounds or 3.2 US tons) is within the capacity of the delivery truck. He also verifies the per-yard weight: at 150 lb/ft3, one cubic yard of concrete weighs about 4,050 pounds.

Example 2: Dr. Chen's Lab Report

Dr. Chen's chemistry students measured the density of an unknown metal sample as 8.94 g/cm3. She asks them to express this in all common density units and identify the metal by comparing with reference values:

• Measured density: 8.94 g/cm3
• In kg/m3: 8,940 kg/m3
• In lb/ft3: 558.05 lb/ft3
• In lb/in3: 0.3229 lb/in3
• Reference: Copper = 8,960 kg/m3

The measured density of 8,940 kg/m3 closely matches the known density of copper at 8,960 kg/m3, with a difference of less than 0.3%. The students successfully identify the unknown metal as copper. The small discrepancy is within the expected measurement uncertainty for a laboratory setting and likely reflects minor air bubbles or impurities in the sample.

Example 3: Olivia's Shipping Cost Calculation

Olivia works in logistics and needs to estimate the shipping weight of a container of cooking oil. The product spec sheet lists the oil density as 0.92 kg/L, and the container holds 1,000 liters. She needs the density in lb/ft3 for the US freight carrier's forms:

• Oil density: 0.92 kg/L
• In lb/ft3: 57.43 lb/ft3
• In kg/m3: 920 kg/m3
• Total weight: 920 kg/m3 x 1.0 m3 = 920 kg (2,028 lb)

Olivia reports the oil density as 57.43 lb/ft3 on the freight forms and calculates the total shipment weight as 920 kg (2,028 pounds). She notes that the oil is less dense than water (density 0.92 vs 1.0 kg/L), so a liter of oil weighs less than a liter of water, an important detail for container capacity and weight distribution planning.

Example 4: Ryan's 3D Printing Material Selection

Ryan is designing a drone chassis and comparing two 3D printing materials. PLA plastic has a density of 1,240 kg/m3 and carbon fiber reinforced nylon has a density of 1,100 kg/m3. He needs to determine the weight difference for his 85 cm3 chassis:

• PLA: 1,240 kg/m3 = 1.24 g/cm3, chassis weight = 85 x 1.24 = 105.4 g
• Carbon nylon: 1,100 kg/m3 = 1.10 g/cm3, chassis weight = 85 x 1.10 = 93.5 g
• Weight savings: 105.4 - 93.5 = 11.9 g (11.3% lighter)

Ryan chooses the carbon fiber nylon at 1.10 g/cm3 over PLA at 1.24 g/cm3, saving 11.9 grams per chassis. For his drone with four chassis sections, the total savings amount to 47.6 grams, which extends flight time by approximately 45 seconds per battery charge. The density calculator helped him quantify the weight difference between materials in units compatible with his CAD software.

Density Reference Table

Densities at standard temperature and pressure (20 degrees C, 1 atm). Actual values may vary with composition and conditions.

Tips and Complete Guide

Understanding Density in Everyday Life

Density explains many everyday phenomena. Oil floats on water because its density (about 920 kg/m3) is lower than water's density (1,000 kg/m3). Hot air balloons rise because heated air is less dense than the surrounding cooler air. Ice floats because frozen water is approximately 9% less dense than liquid water, an unusual property that allows aquatic life to survive in frozen lakes and rivers. When you pick up a golf ball and a table tennis ball, the noticeable weight difference despite similar sizes is entirely due to their different densities. Understanding density helps explain buoyancy, material selection, food preparation (why some ingredients float while others sink), and even geological processes like plate tectonics.

Measuring Density in Practice

To measure density, you need to determine both mass and volume. For regular-shaped solids (cubes, cylinders, spheres), measure dimensions with calipers and calculate volume geometrically. For irregular solids, use water displacement (Archimedes' method): submerge the object in water and measure the volume of water displaced. For liquids, use a graduated cylinder and an analytical balance, or use a hydrometer that directly measures density by floating at different levels in different-density liquids. For gases, use a sealed container of known volume and measure the mass. Digital density meters using the oscillating U-tube method provide very high accuracy (up to 0.00001 g/cm3) and are standard in laboratory and industrial settings.

Density in Engineering and Design

Engineers rely on density data for material selection, structural analysis, and weight optimization. In aerospace, every gram matters, so engineers choose materials with the best strength-to-density ratio. Aluminum (2,700 kg/m3) replaced steel (7,850 kg/m3) in aircraft because it offers adequate strength at roughly one-third the density. Modern composites like carbon fiber reinforced polymer (about 1,600 kg/m3) push this even further. In civil engineering, concrete density affects load calculations for foundations, floors, and bridges. In automotive design, using lighter materials reduces fuel consumption while maintaining crashworthiness. The mass calculator complements density calculations by converting the resulting weight into various units.

Common Mistakes to Avoid

• Ignoring temperature effects: Density varies with temperature. Water's density at 4 degrees Celsius (1,000 kg/m3) differs from water at 80 degrees Celsius (971.8 kg/m3). Always note the temperature when precise density values are required.
• Confusing mass and weight density: In strict physics terminology, density refers to mass per unit volume (kg/m3). Weight density (or specific weight) is weight per unit volume (N/m3). The difference matters in calculations involving buoyancy and gravitational forces.
• Mixing up g/cm3 and kg/m3 by a factor of 1,000: This is the most common density conversion error. Remember that 1 g/cm3 equals 1,000 kg/m3. Water is 1.0 g/cm3 or 1,000 kg/m3, not 1.0 kg/m3.
• Assuming uniform density: Many real-world materials are not uniformly dense. Wood has varying density depending on grain direction and moisture content. Concrete density depends on aggregate type and air content. Always use density values specific to your material grade.
• Forgetting about significant figures: If your mass measurement is accurate to three significant figures, reporting density to six decimal places implies false precision. Match the precision of your result to the precision of your least accurate input measurement.

Frequently Asked Questions