Jugs and Mugs - Measuring Liquids

Capacity is the maximum amount of liquid a container can hold. For example, a tall narrow bottle and a short wide bowl can have the same capacity if they hold the same total amount of water. Capacity helps us understand how much milk is in a packet or how much water is in a bucket.

Standard units of measurement for liquids are Litres ($L$) and Millilitres ($ml$). We use $ml$ for small quantities like a spoonful of medicine or a small juice box, and $L$ for larger quantities like a bucket of water, a fuel tank, or the capacity of a water overhead tank.

The basic conversion rule is $1 L = 1000 ml$. You can visualize this by imagining a large $1$ Litre jug being filled completely by pouring ten smaller $100 ml$ measuring cups into it.

Fractional parts of a litre are important for daily measurements. A half-litre jug holds $500 ml$ ($\frac{1}{2} L = 500 ml$), and a quarter-litre glass holds $250 ml$ ($\frac{1}{4} L = 250 ml$). If you see a bottle marked $750 ml$, it is equal to three-quarters of a litre ($\frac{3}{4} L$).

Measuring cylinders and jugs often have markings called scales on the side. Imagine a transparent jar with horizontal lines: as you pour liquid, the level rises against these marks, allowing you to read the volume directly in $ml$.

When comparing containers, always check the units. A container with $2 L$ is much larger than a container with $500 ml$, even though the number $500$ is bigger than $2$, because $2 L$ is actually $2000 ml$.

To make exactly $1$ Litre using smaller measures, you can combine different amounts. For example, you can combine two $500 ml$ bottles, or four $250 ml$ cups, or five $200 ml$ glasses to reach the $1000 ml$ mark on a large jug.