Solution Density & Specific Gravity Calculator
Calculate solution density from mass and volume, convert density to specific gravity (SG), solve for mass or volume, and read off the Baumé degree. Includes g/mL, kg/m³, kg/L, lb/ft³, lb/gal and multiple water reference temperatures.
Select a calculation, then enter the known values.
Reference density (for SG & Baumé)
Solution density
Formula used: ρ = m / V
1.05 g/mL
Density (g/mL)
1.05
Specific gravity
1,050 kg/m³
Density (kg/m³)
6.905° Bé
Baumé degree
1.05
g/cm³
1.05
kg/L
65.549
lb/ft³
8.763
lb/gal (US)
Interactive Density & Specific Gravity Visual
A hydrometer-style view showing how the solution's specific gravity affects buoyancy and the Baumé reading.
Step-by-Step Density & Specific Gravity Calculation
Here's exactly how this answer was calculated, one step at a time.
Given: mass = 105 g, volume = 100 mL
Step 1: Start with the density formula
Density is mass per unit volume, so it is found by dividing the mass of the solution by the volume it occupies.
ρ = m / VStep 2: Convert the entered units
m = 105 g; V = 100 mLStep 3: Divide mass by volume
ρ = 105 g ÷ 100 mLStep 4: Report the density
ρ = 1.05 g/mL
Calculated result:
1.05 gml
Solution Density & Specific Gravity Calculator: Free Online Tool
This solution density and specific gravity calculator finds density from mass and volume, works out mass or volume when density is known, converts density into specific gravity (SG), and turns a specific gravity value back into a real density. It also reports a Baumé degree reading automatically, which is handy for anyone working with brine, syrup, acid, alcohol, or any liquid where a hydrometer is normally used.
Type in numbers using the units you already have on hand — grams, kilograms, pounds, ounces, millilitres, litres, cubic feet, or US gallons — and the calculator converts everything internally before showing a clean answer along with the written working. It is built for chemistry students, lab technicians, quality control staff, brewers, and anyone who needs a fast, accurate density or specific gravity calculator without digging through a textbook.
What Is Density?
Density tells you how much mass is packed into a given volume of a substance. It is written as ρ (the Greek letter rho) and calculated with the simple formula ρ = m / V, where m is mass and V is volume. A dense liquid, like honey or concentrated sulfuric acid, packs a lot of mass into a small volume. A light liquid, like ethanol or gasoline, packs less mass into the same space.
Density is usually reported in grams per millilitre (g/mL) or grams per cubic centimetre (g/cm³) for liquids, which are numerically identical units. In industrial and engineering contexts you will also see kilograms per cubic metre (kg/m³), kilograms per litre (kg/L), pounds per cubic foot (lb/ft³), and pounds per US gallon (lb/gal). This calculator converts between all of these automatically so you never need to memorise the conversion factors.
What Is Specific Gravity (Relative Density)?
Specific gravity, often shortened to SG and also called relative density, compares the density of a solution to the density of a reference substance — almost always pure water — measured at a specific temperature. The formula is SG = ρ(solution) / ρ(reference). Because it is a ratio of two densities, specific gravity has no units at all; it is simply a number.
A specific gravity greater than 1 means the solution is denser than water and will sink in it. A specific gravity less than 1 means the solution is lighter than water and will float on top. Pure water itself has an SG of exactly 1.000 at its reference temperature, which makes it the natural baseline for comparing salt solutions, syrups, acids, alcohols, and countless industrial liquids.
Density Formula and a Worked Example
Suppose you weigh 105 g of a salt solution and find it fills exactly 100 mL. Using ρ = m / V, the density works out to 105 ÷ 100 = 1.05 g/mL. That single measurement already tells you a lot: since pure water is close to 1.00 g/mL, this solution is noticeably denser, which makes sense for a salt brine.
The same formula rearranges easily. If you already know the density and need the mass, use m = ρ × V. If you know the mass and the density but need the volume, use V = m / ρ. This calculator's mode selector switches between all three rearrangements automatically, so you can solve for whichever quantity you are missing.
How to Calculate Specific Gravity from Density
Once you have a measured density, finding specific gravity is a one-line calculation: divide the solution's density by the reference density. Continuing the salt-solution example, if the solution density is 1.05 g/mL and the reference (water at 20°C) is 0.99820 g/mL, then SG = 1.05 ÷ 0.99820 ≈ 1.052.
Notice that the SG value is almost, but not exactly, the same as the raw density number. That small difference comes from water's own density shifting slightly with temperature, which is why choosing the correct reference matters for precise laboratory or industrial work.
Converting Specific Gravity Back Into Density
Sometimes you are handed a specific gravity reading — from a hydrometer, a spec sheet, or a lab report — and you need the actual density in g/mL or kg/m³. Rearranging the SG formula gives ρ = SG × ρ(reference). So a solution with SG 1.20, measured against water at 4°C (1.000 g/mL), has a density of 1.20 g/mL.
This reverse calculation is common in food science, brewing, and industrial process control, where a hydrometer gives you SG directly and you then need the true density to calculate a batch mass or dose a chemical accurately.
Understanding the Baumé Scale
The Baumé scale (°Bé) is an older hydrometer scale still used in winemaking, sugar syrup production, tanning, and some chemical industries. It has two separate formulas depending on whether the liquid is heavier or lighter than water. For liquids denser than water, °Bé = 145 − (145 / SG). For liquids lighter than water, °Bé = (140 / SG) − 130.
This calculator checks the computed specific gravity and automatically applies the correct formula — heavy or light — so you get a Baumé reading without needing to remember which equation applies. A Baumé value near zero means the liquid is close to pure water; larger positive values on the heavy scale point to a denser solution such as a strong brine or concentrated syrup.
Density Units Explained: g/mL, kg/m³, kg/L, lb/ft³ and lb/gal
Grams per millilitre (g/mL) and grams per cubic centimetre (g/cm³) are identical in value and are the most common units in chemistry labs, since 1 mL equals exactly 1 cm³. Kilograms per litre (kg/L) is also numerically the same as g/mL, which is a convenient coincidence that trips up many students the first time they see it.
Kilograms per cubic metre (kg/m³) is the SI unit used in engineering and is exactly 1000 times the g/mL value. Pounds per cubic foot (lb/ft³) and pounds per US gallon (lb/gal) are common in American manufacturing, plumbing, and fuel industries; pure water works out to roughly 62.4 lb/ft³ and 8.34 lb/gal. This calculator shows all of these side by side so you never have to look up a conversion factor mid-calculation.
Why the Reference Temperature Matters
Water's density is not perfectly constant — it changes slightly as temperature rises or falls, and it actually peaks at exactly 4°C, where it equals 1.000 g/mL. At 20°C, water is a touch lighter at about 0.9982 g/mL, and at 25°C it drops further to about 0.99705 g/mL. The petroleum industry traditionally uses 60°F (about 15.56°C) as its reference point, giving 0.99904 g/mL.
Because specific gravity is a ratio, picking the wrong reference temperature introduces a small but sometimes meaningful error, especially in regulated industries like pharmaceuticals, food production, and petroleum trading. This calculator lets you pick the exact reference your procedure specifies, or enter a fully custom reference density if your standard uses something other than water.
Real-World Uses of Density and Specific Gravity
Brewers and winemakers track specific gravity before and after fermentation to estimate sugar content and alcohol yield. Battery technicians measure the specific gravity of sulfuric acid electrolyte to judge a lead-acid battery's charge state. Nurses and lab technicians check urine specific gravity as a quick hydration and kidney-function indicator.
In manufacturing, density and specific gravity checks confirm that a batch of syrup, cleaning solution, coolant, or paint matches its formulation before it ships. Geologists use specific gravity to help identify minerals, and the petroleum industry relies on a related scale, API gravity, to grade crude oil quality. All of these fields lean on the same underlying formula: ρ = m / V, and the same comparison: SG = ρ(solution) / ρ(reference).
Common Mistakes When Calculating Density or Specific Gravity
A frequent error is mixing volume units — entering millilitres while a density figure is quoted in litres, or vice versa. Always double-check that mass and volume are in units that match the formula you intend to use, or let the calculator's unit selectors handle the conversion for you.
Another common slip is forgetting that specific gravity has no unit; writing '1.05 g/mL' for an SG value is incorrect, since SG is already a ratio of two densities and the units cancel out. Finally, remember that the Baumé scale needs the correct heavy or light formula — using the wrong one produces a reading with the wrong sign or magnitude, which is why this calculator picks the formula for you automatically based on whether SG is above or below 1.
Solution Density & Specific Gravity FAQ and Quick Reference
Use ρ = m / V to calculate density; rearrange to m = ρ × V for mass, or V = m / ρ for volume. Use SG = ρ(solution) / ρ(reference) to convert a density into specific gravity, and ρ = SG × ρ(reference) to convert it back. For Baumé, apply °Bé = 145 − 145/SG for liquids heavier than water, or °Bé = 140/SG − 130 for liquids lighter than water.
This free online density and specific gravity calculator is meant for educational, laboratory-planning, and quality-control estimation. For regulated, clinical, or safety-critical measurements, always verify results against a calibrated instrument and your organisation's validated procedure.
Frequently Asked Questions
What is the formula for density?
Density equals mass divided by volume: ρ = m / V, commonly expressed in g/mL or kg/m³.
How do I convert density to specific gravity?
Divide the solution's density by a reference density, almost always water at a stated temperature: SG = ρ(solution) / ρ(reference).
Is specific gravity the same as density?
No. Density has units like g/mL, while specific gravity is a unitless ratio comparing a solution's density to a reference substance.
How do I convert specific gravity to Baumé degrees?
Use °Bé = 145 − 145/SG for liquids denser than water, or °Bé = 140/SG − 130 for liquids lighter than water.
Why does water's reference density change with temperature?
Water is densest at 4°C (1.000 g/mL) and becomes slightly less dense as temperature rises, so labs specify a reference temperature for accurate specific gravity readings.