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The metric system · The metric system

Capacity in the Metric System

A soda bottle says "2 L." A medicine cup says "5 mL." A swimming pool holds thousands of liters. All of these are capacity: how much fits inside a container. Here's a question to keep in mind: how many 250 mL cups can you fill from one 2 L bottle?

The Liter and Everyday Benchmarks

A liter is a little more than a quart (about $1.06$ quarts). Science labs, nutrition labels, and soda bottles all use metric capacity.

Four containers of increasing size: a teaspoon of about 5 milliliters, a soda can of about 355 milliliters, a 2-liter bottle, and a 10-liter bucket. teaspoon about 5 mL soda can about 355 mL big bottle 2 L bucket about 10 L
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Match each of the following objects with the unit of capacity in the Metric System that seems most appropriate to measure what fits inside it: An Olympic swimming pool.…

Match each of the following objects with the unit of capacity in the Metric System that seems most appropriate to measure what fits inside it:

  • An Olympic swimming pool.

  • A can of cola.

  • A syringe for giving a vaccine.

  • A mop bucket.

Swimming pool Bucket Can Syringe
Solve

The Metric Ladder

The metric system is built on tens. Each unit of capacity is $10$ times the next smaller one, and the prefix tells you the size.

Unit Symbol In liters
kiloliter kL $1{,}000$ L
hectoliter hL $100$ L
dekaliter daL $10$ L
liter L $1$ L
deciliter dL $0.1$ L
centiliter cL $0.01$ L
milliliter mL $0.001$ L

A memory trick for the order: King Henry Doesn't Usually Drink Chocolate Milk (kilo, hecto, deka, unit, deci, centi, milli).

Ladder of metric capacity units from kiloliter to milliliter. Moving one step right multiplies by 10 and one step left divides by 10. kL hL daL L dL cL mL ×10 ÷10

Why does it work? Each unit holds exactly $10$ of the next smaller one: $1\text{ L} = 10\text{ dL}$ and $1\text{ dL} = 10\text{ cL}$. Stack several steps and you just keep multiplying by $10$.

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Complete the following equalities by performing the necessary unit conversions: a) $25 L = ??? dL$ b) $4.500 mL = ??? L$ c) $0,75 kL = ??? L$ d) $32 cL = ??? mL$

Complete the following equalities by performing the necessary unit conversions:

  1. a) $25 L = ??? dL$
  2. b) $4.500 mL = ??? L$
  3. c) $0,75 kL = ??? L$
  4. d) $32 cL = ??? mL$
Solve

Converting Between Units

To convert, count the steps on the ladder. Then decide: going to a smaller unit means more of them (multiply), and going to a larger unit means fewer of them (divide). Each step is a factor of $10$, so you can just move the decimal point.

Steps Factor
1 step $10$
2 steps $100$
3 steps $1{,}000$
Converting 1,200 milliliters to 1.2 liters by moving the decimal point three places to the left. 1,200 mL 3 places left 1.2 L

Some problems call this complex vs. incomplex form; more on that in the next section.

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To celebrate the end of the term, the 7th grade students have bought several bottles of orange juice. If each bottle has a capacity of $1,5\ L$, express this quantity in…

To celebrate the end of the term, the 7th grade students have bought several bottles of orange juice. If each bottle has a capacity of $1,5\ L$, express this quantity in centiliters ($cL$) and in milliliters ($mL$).

1.5 L Orange juice 1.5 L ? cL ? mL × 10² × 10 × 10³
Solve
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At a music festival for teenagers, the organizers have bought several types of water containers to distribute among the attendees. They have a main tank of…

At a music festival for teenagers, the organizers have bought several types of water containers to distribute among the attendees. They have a main tank of $2,5\text{ kL}$, packs of bottles of $50\text{ cl}$, and large bottles of $8\text{ L}$.

If they want to know the total water available in liters, perform the following conversions:

  1. a) Express the capacity of the tank in liters.
  2. b) How many liters are there in a pack containing $12$ bottles of $50\text{ cl}$?
  3. c) If they have served $15$ full large bottles, how many deciliters have they distributed?
Tank 2.5 kL x12 Pack 50 cl per bottle x15 Large bottle 8 L
Solve

Mixed Units

A capacity can be written with one unit ($4.325$ L) or with several units ($4$ L $3$ dL $2$ cL $5$ mL). Some problems call the second way complex form and the first way incomplex form. To go from mixed units to one unit, convert each part and add. To go the other way, split the amount from the biggest unit down.

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In Science class, the students are using a graduated cylinder. If the cylinder shows a capacity of $35\ cL$, express this measurement in complex form (that is, using…

In Science class, the students are using a graduated cylinder. If the cylinder shows a capacity of $35\ cL$, express this measurement in complex form (that is, using liters and centiliters).

Solve
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A farmer has a small tank for watering his pots with a capacity of $2\ dal$ and $5\ L$. How many $1\ L$ bottles will he be able to fill with the tank completely full?

A farmer has a small tank for watering his pots with a capacity of $2\ dal$ and $5\ L$. How many $1\ L$ bottles will he be able to fill with the tank completely full?

2 dal 5 L 1 L How many bottles?
Solve
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In the Natural Sciences laboratory, the students are preparing a mixture for an experiment on density. They have used the following quantities of different liquids:…

In the Natural Sciences laboratory, the students are preparing a mixture for an experiment on density. They have used the following quantities of different liquids:

  • Distilled water: $1\text{ L}$ and $25\text{ cl}$.

  • Alcohol: $4\text{ dl}$ and $5\text{ ml}$.

  • Oil: $150\text{ ml}$.

Express the total quantity of the mixture in incomplex form in centiliters ($cl$) and then in complex form using liters, deciliters, and milliliters.

Solve

Adding and Comparing Capacities

You can only add or compare capacities after you write them in the same unit.

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An athlete carries a hydration backpack for her training. If she has filled the tank with $1.200\ mL$ of water and then added an extra $0,5\ L$ bottle, how many liters…

An athlete carries a hydration backpack for her training. If she has filled the tank with $1.200\ mL$ of water and then added an extra $0,5\ L$ bottle, how many liters of water is she carrying in total?

1.200 mL + 0,5 L = ? ? L
Solve
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A recipe for making a sponge cake indicates that $2\ dL$ of milk must be added. If we have an open one-liter carton in the fridge with $450\ mL$ left, do we have enough…

A recipe for making a sponge cake indicates that $2\ dL$ of milk must be added. If we have an open one-liter carton in the fridge with $450\ mL$ left, do we have enough milk for the recipe? Justify your answer by converting both quantities to the same unit.

Solve
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Order the following capacity measurements from smallest to largest. To be able to compare them, first convert them all to the unit of liters ($L$): $0,007\text{ kL}$…

Order the following capacity measurements from smallest to largest. To be able to compare them, first convert them all to the unit of liters ($L$):

  • $0,007\text{ kL}$

  • $75\text{ dl}$

  • $725\text{ cl}$

  • $7.100\text{ ml}$

  • $0,8\text{ dal}$

Solve

Liters and Cubic Units

Capacity and volume are connected in the metric system. A cube that is $10$ cm on each side has a volume of $10 \times 10 \times 10 = 1{,}000\text{ cm}^3 = 1\text{ dm}^3$, and it holds exactly 1 liter.

A cube with a volume of 1 cubic decimeter holds the same amount as a 1-liter bottle, and a cube of 1 cubic centimeter holds 1 milliliter. 1 dm³ (10 cm each side) = 1 L 1 cm³ = 1 mL

The volume of a rectangular prism is $V = \ell \cdot w \cdot h$ (length times width times height). If the edges are in dm, the answer is in dm³, which is the same number of liters. If the edges are in cm, the answer is in cm³, which is the same number of mL.

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Remember that in the metric system there is a direct relationship between volume and capacity. If we have a cube-shaped container that has a volume of exactly $1\ dm^3$,…

Remember that in the metric system there is a direct relationship between volume and capacity. If we have a cube-shaped container that has a volume of exactly $1\ dm^3$, how many liters of water fit inside it? And how many milliliters fit in a volume of $1\ cm^3$?

1 dm 1 dm 1 dm 1 dm³ 1 cm 1 cm³ 1 dm³ = 1 L 1 cm³ = 1 mL
Solve
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An aquarium has the shape of a cuboid (rectangular prism) with the dimensions shown in the image. Knowing that $1\text{ dm}^3$ is exactly equivalent to $1\text{ liter}$…

An aquarium has the shape of a cuboid (rectangular prism) with the dimensions shown in the image. Knowing that $1\text{ dm}^3$ is exactly equivalent to $1\text{ liter}$ of capacity:

  1. a) Calculate the volume of the aquarium in $\text{dm}^3$.
  2. b) How many liters of water are needed to fill the aquarium completely?
  3. c) If the aquarium currently contains $45.000\text{ ml}$ of water, how many liters are left to fill it?
45,000 ml 60 cm 25 cm 40 cm
Solve
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An aquarium in the shape of a rectangular prism has internal dimensions of $80\text{ cm}$ long, $30\text{ cm}$ wide, and $50\text{ cm}$ high. For safety, it is…

An aquarium in the shape of a rectangular prism has internal dimensions of $80\text{ cm}$ long, $30\text{ cm}$ wide, and $50\text{ cm}$ high. For safety, it is recommended not to fill it to more than $\frac{4}{5}$ of its total capacity. If it currently contains $84\text{ liters}$ of water, how many $250\text{ cl}$ buckets are left to pour in to reach the maximum recommended level?

80 cm 30 cm 50 cm 84 L Max (4/5) Limit 250 cl How many?
Solve

Bigger and Smaller Cubic Units

For big tanks and pools we use cubic meters. For tiny drops we use cubic millimeters. For cubic units, each step is a factor of $1{,}000$, not $10$.

Chain of cubic units from cubic meter to cubic millimeter, each step a factor of 1,000, with the matching capacity under each unit. m³ dm³ cm³ mm³ ×1,000 ×1,000 ×1,000 1,000 L 1 L 1 mL 0.001 mL
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A garden swimming pool has a total capacity of $12\text{ m}^3$. We want to fill it using a hose that delivers a flow rate of $25\text{ liters}$ per minute. a) How many…

A garden swimming pool has a total capacity of $12\text{ m}^3$. We want to fill it using a hose that delivers a flow rate of $25\text{ liters}$ per minute.

  1. a) How many liters of water fit in the pool? (Remember that $1\text{ m}^3 = 1.000\text{ L}$).
  2. b) How many minutes will it take to fill the pool completely?
  3. c) Express the previous time in hours and minutes.
12 m³ 25 L/min
Solve
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In a perfume factory, they want to bottle a batch of $0,15\text{ m}^3$ of lavender essence. Three types of bottles are used: Half of the essence is bottled in…

In a perfume factory, they want to bottle a batch of $0,15\text{ m}^3$ of lavender essence. Three types of bottles are used:

  • Half of the essence is bottled in $125\text{ ml}$ bottles.

  • A third of the total is bottled in $0,5\text{ dl}$ bottles.

  • The rest of the essence is bottled in $10\text{ cm}^3$ samples.

Calculate how many bottles of each type are needed.

Solve
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A municipal swimming pool $25\text{ m}$ long and $12\text{ m}$ wide is filled to an average depth of $1,8\text{ meters}$. Due to evaporation from the heat, the water…

A municipal swimming pool $25\text{ m}$ long and $12\text{ m}$ wide is filled to an average depth of $1,8\text{ meters}$. Due to evaporation from the heat, the water level drops by $5\text{ mm}$ each day.

  1. a) How many liters of water are lost to evaporation in a single day?
  2. b) If water costs $\$1,20\text{ \$}$ per cubic meter ($m^3$), how much money does the loss of water cost the city council after a week of intense heat?
25 m 12 m 1.8 m 5 mm
Solve

Rates and Word Problems

Capacity shows up in rates: price per liter, drops per minute, liters per minute. Before you divide or multiply by a rate, put all the quantities in compatible units.

A leak of 1 milliliter per minute becomes 60 milliliters per hour and 1,440 milliliters per day after multiplying by 60 and then by 24. 1 mL per min 60 mL per hour 1,440 mL per day ×60 ×24
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A faulty tap leaks water at a rate of $15\text{ gotas}$ per minute. If each drop has a volume of approximately $0,05\text{ ml}$: a) How many milliliters of water are…

A faulty tap leaks water at a rate of $15\text{ gotas}$ per minute. If each drop has a volume of approximately $0,05\text{ ml}$:

  1. a) How many milliliters of water are lost in an hour?
  2. b) How many liters of water will have been wasted after a full day ($24$ hours)?
  3. c) If water costs $0,002\text{ \$}$ per liter, how many dollars are lost in a month of $30$ days due to this leak?
15 drops 1 min 0.05 ml 1 drop
Solve
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We want to compare the value for money of two containers of liquid detergent of the same brand: Container A: $1.800\text{ ml}$ at a price of $4,50\text{ \$}…

We want to compare the value for money of two containers of liquid detergent of the same brand:

  • Container A: $1.800\text{ ml}$ at a price of $4,50\text{ \$}$.

  • Container B: $0,25\text{ dal}$ at a price of $6,50\text{ \$}$.

Calculate the price per liter of each container and determine which is more economical. If a family consumes $15\text{ cl}$ of detergent in each wash, how many washes can they do with the largest container?

1.800 ml $4,50 Container A 0.25 dal $6,50 Container B 1 lavado = 15 cl
Solve
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A broken faucet in a middle school leaks one drop of water every $2\text{ seconds}$. If each drop has an average volume of $50\text{ mm}^3$, calculate how many…

A broken faucet in a middle school leaks one drop of water every $2\text{ seconds}$. If each drop has an average volume of $50\text{ mm}^3$, calculate how many $2\text{ decaliters}$ containers would be filled if the faucet were leaking water throughout the whole month of April.

50 mm³ 1 drop / 2 s APR 30 days How many containers? 2 daL
Solve

Summary

See all the exercises in this section