Doctors say it everyday -” Water is essential for your health”. Is water that important?

Well, it regulates your body temperature, helps your brain function, and did I mention – it helps excrete your body waste through urination, perspiration, and defecation.

Now we know about water, but what is the density of water? If you’re still in school or like to study Physics, you know, “For any substance, the density is the mass per unit volume”. But if you don’t know, or you have doubts, no worries. Here in this blog, we will discuss about “Density of Water” in detail which will be helpful in your exam when you calculate a value using the density of water.

So, what is “Density”?

The density of any object or substance is defined as the mass present in a unit volume of that object or substance. If you study the gas theory, you will find another useful notion which is number density. If m is mass and V is volume, then material density is given by ρ=m/V. And, if N is the total number of particles, then number density will be n=N/V, where. Density is an intrinsic property of matter and it is expressed as g/cm3 in CGS and kg/m3 in SI methods. In most places, the density of water is expressed as 1 g/cm3, but in some cases, you might find a different value with a different unit. For example, the density of water can be written as 1 g/ml (water’s density is gram per milliliter) or 1 g/cm3 (1 gram per cubic centimeter). Here is a simple chart for your understanding of “water density”:

Unit Water Density
Density of water g/mL 1 g/mL
Density of water g/cm3 1 g/cm3
Density of water lb/ft3 62.4 lbs/ft3
Density of water kg/m3 1000 kg/m3

Water’s density depends on both the temperature of the area and air pressure. These variations in density are very less. Unless you need to know the exact data or the experiment takes place in an area with an extreme temperature/pressure, you can use 1 g/cm3 for water density. If we are talking about density vs temperature, we all know, at room temperature, water remains in a liquid state. The density of seawater is higher than normal water because of the presence of salt and minerals. At the sea surface, the seawater density is about 1027 kg/m3.

Well, you must remember a fact about water density. We know, water density can be expressed in different units such as lb/ft3 or g/ml or g/cm3 but, the actual density of water is not really 1 g/ml, a bit less than 1. The maximum density of water is 0.9998395 g/ml at 39.2° F (4.0° C), but the “Density of Pure Water” is different at different temperatures. Remembering a list of values is tough, so you can refer to this table:

Temperature Density Weight
(°F/°C) (grams/cm3) (pounds/ft3)
32°F/0°C 0.99987 62.416
39.2°F/4.0°C 1 62.424
40°F/4.4°C 0.99999 62.423
50°F/10°C 0.99975 62.408
60°F/15.6°C 0.99907 62.366
70°F/21°C 0.99802 62.3
80°F/26.7°C 0.99669 62.217
90°F/32.2°C 0.9951 62.118
100°F/37.8°C 0.99318 61.998
120°F/48.9°C 0.9887 61.719
140°F/60°C 0.98338 61.386
160°F/71.1°C 0.97729 61.006
180°F/82.2°C 0.97056 60.586
200°F/93.3°C 0.96333 60.135
212°F/100°C 0.95865 59.843

Did you know, Ice is less dense than water?

Unlike ordinary liquids, water density decreases from 4 degree C to 0 degree C. Above 4 degree C, the density of water decreases with increasing temperature. This behavior is called the “density anomaly”. Due to this property, the density of ice is less than the density of water at 4 degree C. Surprisingly, almost all of the volume of an iceberg lies below the waterline, not above it. Upon freezing, ice density decreases by about 9 percent. This property is significant for life. If water was less heavier than ice, then the ice would sink to the bottom of oceans and lakes and they would freeze from the bottom up. But as you might know that water is an excellent thermal insulator, deep lakes might never thaw in the summer.

In cold regions (during winter as well as in normal time), the temperature of the atmosphere slowly decreases to 0 degree C and further below. The water on the surfaces of oceans and lakes cool down and it becomes heavy. Following the density rule the cold water comes down and the hot water rises. This convection process goes on until the water of lower surfaces reaches a temperature around 4 degree C. Since at this point of time the density of the water is maximum, the water from upper surfaces of lakes and oceans cannot come down and the convection process stops. Then the upper layers of lake water and ocean water cool down even more and it becomes ice. That ice then floats on the surface of the lake or ocean water. The lower layers of the water however stay at 4 degree C, which is sufficiently warm for any aquatic animal to survive.

Now, coming to the effect of pressure on density. The normal of density is – density increases when the pressure increases and it decreases when the pressure decreases. As pressure increases, the molecules of any substance come closer that resulting in a higher density. On the other hand, when pressure decreases, the molecules go far from each other. Due to this reason, the density reduces. And, the same logic is applicable to water also. Pressure affects density, but water isn’t very much compressible, so it is not usually a significant factor.

How to Calculate the Density of a Liquid 

Now you know what the density of water is at different temperatures, but what if you want to find the density of some other liquid and not water? Don’t worry, it’s quite easy! Just divide the mass by its volume and you will find the density of any substance easily. Here is the formula for density: ρ=m/v, where the density is represented by the symbol ρ that’s pronounced as “rho”.

You can try to find the density of milk, seawater, glycerin, and some other common liquids using this formula. There are 3 simple ways to calculate density, depending on whether you’re trying to find the density of an irregular object, a regularly shaped object, or just any liquid.

If it’s a regular object, such as rectangles, triangles, squares, etc. you have to calculate the mass and volume of that object at first. The mass of an object means how much it weighs. Based on their height, length, and width all regular polygons have an equation for determining their volume.

For example, say you have a piece of aluminium piece (rectangular) that weighs 865 g. It’s dimensions are 10cm x 8cm x 4cm. And, you have to find its density. It’s easy, right? You can do it in just 2 steps. At first multiply the width, length, and height (equation for the volume of a rectangle) and find the volume of the piece by.

V = 10cm x 8cm x 4cm = 320 cm3

Now you know the volume, you just need to divide the mass by the volume to get the density of the aluminium sheet ρ=m/v = 865g/320cm3 = 2.7g/cm3. So the density of aluminium is 2.7g/cm3.

But what if it’s an irregular piece of aluminium or any other object? How to find the volume in that case?

If the object is in an irregular shape, you can’t calculate its volume easily. You need to add some more steps before you find its density. First, find a cylinder, then fill it with water, then place the irregular object in that cylinder filled with water. Now measure the volume of water it displaces. Do you know Archimedes’ Principle? It states that an object displaces a volume of liquid equal to its own volume. Now you know the amount of water displaced by the aluminium piece, use the normal density equation ρ=m/v to find the density of any regular substance or object

So if you had a different, irregular piece of aluminium that weighed 550g. Suppose, the piece displaced 204mL of water in that graduated cylinder. So your density equation will look like

ρ = 550g/204mL = 2.7g/mL. But the aluminium sheet was a solid object, so if you want to find the density of a liquid, just pour the liquid into the graduated cylinder, next check its volume and then follow the last step, which is nothing but to calculate the density of that liquid.

The easiest way to measure the density of any liquid, including water, is to use a hydrometer. A simple hydrometer is nothing but plastic or thin glass tube with a bulb-shaped at one end. The scales on a hydrometer can be calibrated to Brix, Alcohol, Baume, API, and others for specific chemicals. If you look closely at the hydrometer tube, you can see those marked lines on the stem which indicate how far the bulb sinks in the liquid. The higher the bulb floats, the higher the density, and the lower the bulb sinks, the lower the density of that liquid. You should take a liquid with known density and then you can calibrate by floating the hydrometer in that liquid.

Water is the standard liquid because it has a specific gravity of 1.000 at about 4°C.

Other than the 3 ways mentioned above, you can find the density of a liquid by measuring volume and mass.

  • First note down the weight of a graduated beaker or
  • Then choose the liquid, pour and record the volume
  • Now just weigh the glassware filled with the
  • Next, find the mass of that Add up the mass of glass & liquid and subtract the weight of the glass from that value.
  • Now find the density of the liquid by dividing the mass of the liquid by the

Hydrometers have many uses but before you use them you must have a general idea of the scale you need and the anticipated value on that specific scale for the process you are doing. Hydrometers are also used in the dairy industry to measure the fat content of milk, which is also called Lactometer. If you want to know the sugar content of any wine or beer, you can use this Hydrometer and decide about the fermentation process. Even for soil analysis also Hydrometers are used. Interesting, isn’t it?

Summary: What Is the Density of Water?

So we have come to an end. Let’s summarize what we have discussed so far in this blog. Water density is rounded to 1000 kg/m3 in S.I. unit or 1 g/cm3 in C.G.S unit unless you need an exact value or you are inclined towards the accuracy or conducting a lab or any other Science experiment in extreme temperatures. And, as I said, the density of water changes depending on the temperature and pressure, both. So if you’re doing an experiment at a temperature that is close to the water’s freezing or boiling point, you’ll need to consider using a different value and take into account the change in density. And, can you tell if ice and steam are denser than water or less dense than water? Well, the answer will be less.

The equation for density is mass by volume, i.e. ρ=m/v.

In order to measure the density of any substance, regular or irregular, check how much liquid is displaced by that object. For a regularly shaped object, find its volume and proceed. But, if it’s an irregular object, then measure the volume of water or the liquid and how much water/ liquid an irregular object displaces in a graduated cylinder. And, the last one is, just use a hydrometer to measure the density of a liquid. Hope this blog will help you understand all about the density of water and how to measure the density of water or any liquid easily. For any doubt, feel free to send your query or just drop your message in the comment section.