Ohm's Law Calculator (V = I × R)
Calculate voltage, current or resistance using Ohm's Law (V=I×R). The calculator also computes electric power. Fast, free and no registration required.
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Density Calculator
Density (ρ) is one of the most fundamental physical properties of any substance — it tells you how much mass is packed into a unit of volume. The formula for density is ρ = m / V, where m is mass in kilograms and V is volume in cubic metres. Using this calculator you can instantly find the density of a material when you know its mass and volume, or work backwards to find the mass from density and volume, or the volume from density and mass. The calculator returns results in both kilograms per cubic metre (kg/m³) and grams per cubic centimetre (g/cm³), making it useful across physics, chemistry, materials engineering and everyday problem-solving. All results are rounded to 4 significant figures for precision without unnecessary decimal places. This tool is ideal for high-school and university students studying physics or chemistry, for engineers working with material specifications, and for anyone who needs a quick and reliable density conversion. Simply select the calculation mode (density / mass / volume), enter the known values, and press Calculate.
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How the density calculator works
The calculator supports three calculation modes: 1. DENSITY mode: ρ = m / V — enter mass (kg) and volume (m³) and the calculator returns density in kg/m³ and g/cm³. 2. MASS mode: m = ρ × V — enter density (kg/m³) and volume (m³) and the calculator returns mass in kilograms. 3. VOLUME mode: V = m / ρ — enter mass (kg) and density (kg/m³) and the calculator returns volume in cubic metres. All results are rounded to 4 significant figures. Division-by-zero is handled gracefully — if the divisor is zero, the result is returned as 0 rather than an error.
Example: water and iron density
Water: mass 1 kg, volume 0.001 m³ (1 litre) → density = 1/0.001 = 1000 kg/m³ = 1 g/cm³. Iron: mass 7.874 kg, volume 0.001 m³ → density = 7874 kg/m³ = 7.874 g/cm³. Reverse example (mass): a block of aluminium (ρ = 2700 kg/m³) with volume 0.002 m³ has mass m = 2700 × 0.002 = 5.4 kg. Volume example: a gold coin of mass 30 g (0.03 kg) and density 19 320 kg/m³ has volume V = 0.03/19 320 ≈ 0.00000155 m³ ≈ 1.55 cm³.
Frequently asked questions
What is density?
Density is the ratio of a substance's mass to its volume, expressed as ρ = m/V. The higher the density, the more mass is contained in the same volume. The SI unit of density is kg/m³, though g/cm³ is also widely used, especially in chemistry and materials science.
What is the density of water?
Pure water has a density of approximately 1000 kg/m³ (1 g/cm³) at 4°C, which is its temperature of maximum density. At 20°C it is slightly lower, around 998 kg/m³. Water density is the standard reference point for specific gravity (relative density) calculations.
What are the densest substances on Earth?
The densest naturally occurring elements are osmium (22 590 kg/m³) and iridium (22 560 kg/m³), followed by platinum (21 450 kg/m³) and gold (19 320 kg/m³). Among common industrial materials, lead (11 340 kg/m³) and steel (7 850 kg/m³) are notably dense.
Why do some objects float and others sink?
An object floats when its average density is lower than the density of the liquid it is placed in, and sinks when its average density is higher. A solid steel ball sinks in water because its density (~7850 kg/m³) far exceeds water's density (1000 kg/m³). A steel ship floats because its hull encloses large volumes of air, making the average density of the whole ship less than 1000 kg/m³.
What is the density of air?
At standard conditions (20°C, 1 atm), the density of dry air is approximately 1.204 kg/m³. This is much lower than liquids, which is why hot-air balloons and helium balloons rise — their average density is lower than the surrounding air.
How does density change with temperature?
Most substances expand when heated, so their density decreases as temperature rises. Water is a notable exception between 0°C and 4°C: it contracts as it warms, reaching maximum density at 4°C. Above 4°C it expands normally. This anomaly is critical for aquatic life, as it prevents lakes from freezing solid.
How do I calculate mass from density and volume?
Use the formula m = ρ × V. For example: 2 litres (0.002 m³) of water (ρ = 1000 kg/m³) has mass m = 1000 × 0.002 = 2 kg. Switch the calculator to MASS mode, enter the known density and volume, and it will compute the mass instantly.
How do I calculate volume from density and mass?
Use the formula V = m / ρ. For example: a block of concrete (ρ = 2300 kg/m³) with mass 460 kg has volume V = 460 / 2300 = 0.2 m³. Switch to VOLUME mode, enter the mass and density, and the calculator returns the volume in m³.
What is specific gravity (relative density)?
Specific gravity is the ratio of a substance's density to the density of water (1000 kg/m³ or 1 g/cm³). It is dimensionless. Substances with specific gravity below 1 float on water; those above 1 sink. For example, oak wood has a specific gravity of about 0.7, while iron's is about 7.87.
What are the typical densities of common materials?
Common reference densities: air 1.2 kg/m³, wood 400–900 kg/m³, water 1000 kg/m³, concrete 2300 kg/m³, aluminium 2700 kg/m³, steel 7850 kg/m³, copper 8960 kg/m³, lead 11 340 kg/m³, gold 19 320 kg/m³. These values are at room temperature and may vary by alloy or grade.
Results are for informational purposes only. The calculator applies the physical formulae ρ = m/V, m = ρ×V and V = m/ρ. Real material properties may vary with temperature, pressure and composition. Do not use results for industrial applications without independent verification.