Capacity conversion (mL ↔ L)

1Summary 重點摘要

1 L = 1000 mL, multiply by 1000 to go large → small.

2Vocabulary cards Vocabulary

3Step by step Steps

1. Step 1: The main rate1 L = 1000 mL is the fixed link between litres and millilitres; memorise this line and every capacity conversion has a basis. Litres measure larger amounts of liquid, such as a 1.5 L bottle of soft drink; millilitres measure smaller amounts, such as a 250 mL carton of milk. The two units differ by exactly 1000 times, so every conversion is a multiply or a divide by 1000. A common mistake is remembering the rate as 100, writing 2 L = 200 mL; a life check shows two 200 mL bottles would not even fill one cup, exposing the error.
2. Step 2: Big to small (× 1000)Litres to millilitres multiplies by 1000: 2.5 L = 2.5 × 1000 = 2500 mL, the decimal point moving three places right. Why does the number grow? Because millilitres are the smaller unit, so the same liquid must give a larger value; 2.5 L can never equal 250 mL. The rule reads: the unit shrinks and the number grows, the same pattern as weight conversion. A common slip is moving too few places, writing 25 mL for 2.5 L; after finishing, compare the numbers, and a smaller result signals a reversed direction or a short move.
3. Step 3: Small to big (÷ 1000)Millilitres to litres divides by 1000: 3500 mL = 3500 ÷ 1000 = 3.5 L, the point moving three places left. The reason is that litres are the larger unit, so the number must shrink; 3500 becomes only 3.5. The motto is big-to-small multiplies, small-to-big divides, and these two lines keep the direction safe. The usual error is moving too few places, such as writing 35 L for 3500 mL; verifying with 35 × 1000 = 35000, which does not match, shows the correction needed, so make multiply-back checks a habit.
4. Step 4: Small values tooValues under a litre follow the same method: 250 mL = 250 ÷ 1000 = 0.25 L, the point moving three places left with zeros padded, treating 250 as 0250 first. Everyday anchors build the feel: a cup of water is about 250 mL, which is 0.25 L, and a tablespoon is about 15 mL, which is 0.015 L. A common mistake is padding too few zeros and writing 2.5 L for 250 mL; remember that any amount below 1000 mL becomes less than 1 litre, so a result above 1 always calls for a check on the three-place move.
5. Step 5: Unify before addingCapacities in different units cannot be added directly: for 1 L + 500 mL, turn 1 L into 1000 mL first, then add, 1000 + 500 = 1500 mL, which is 1.5 L. The reason is that litres and millilitres differ by 1000 times, so adding 1 and 500 directly gives a meaningless 501. Unifying the units is the fixed first step for mixed units: convert first, calculate second. The common error is forgetting to unify, or converting in the wrong direction; a quick everyday estimate of the total catches most mistakes.
6. Step 6: Everyday anchorsKeeping everyday capacities in mind makes estimating and converting surer: a large bottle of soft drink is 1.5 L or 1500 mL, a cup of water about 250 mL or 0.25 L, a small water bottle about 500 mL or half a litre, a bucket about 15 L, and a tablespoon about 15 mL. With these anchors an unreasonable answer stands out at once, such as a cup holding 250 L. The common fault is lacking a feel for size, so an absurd result goes unnoticed; check every answer against daily experience as well as by calculation.

4Diagrams Diagrams

5Worked example Example

6Common mistakes Mistakes

7Quick check Quick check

8Recap Recap

• 1 L = 1000 mL
• L → mL multiply by 1000; mL → L divide by 1000
• Shift the point three places: 2.5 L = 2500 mL
• Unify units before adding or subtracting
• Everyday anchors: big bottle 1.5 L, juice box 250 mL