You should add a comma between two adjectives when they can be reordered. We avoid the use of comma if the adjectives cannot be rearranged.

Add a comma between two adjectives if they can be reordered.

My sister is a confident, determined girl.

My sister is a determined, confident girl.

Omit it if the adjectives cannot be rearranged.

We explored an incredible Brazilian beach.

We explored a Brazilian incredible beach.

We explored an incredible, Brazilian beach.

1. How to Know If a Comma Is Needed

A way to determine if a comma is required between two adjectives is to mentally put the conjunction "and" between them. As a result:

• If the sentence makes sense (even if you change the order of the adjectives), add a comma.
• If the sentence doesn't seem correct, do not use a comma to separate the adjectives.

Example A

The bulky, large piano needs restoration.

The bulky large piano needs restoration.

We know that a comma is required in the example above because we can say "bulky and large piano" as well as "large and bulky piano".

Example B

She bought a small picnic table.

She bought a small, picnic table.

The comma is incorrect because we cannot reorder the adjectives. We don't say "a picnic small table".

Example C

The quiet, respectful students listened to the teacher.

The quiet respectful students listened to the teacher.

We need a comma because we can say "the quiet and respectful students" or "the respectful and quiet students". Both are correct.

Example D

I bought three small paintings.

I bought three, small paintings.

Since we cannot rearrange the adjectives, the comma must be omitted.

2. More Guidelines to Determine Whether to Use Commas

Noticing if a particular order of adjectives sounds right or wrong is not always easy for a non-native speaker. However, there are particular situations where the context can help us determine whether a comma is required or not.

Commas and colors

When using three or more colors to describe a noun, add commas.

I love your red, black, and green dress.

The blue, white, and red flag of France was adopted in 1790.

When using only two colors, use the conjunction "and" (no comma) instead:

I bought a black and white T-shirt.

Synonyms

You can use two or more synonyms, or closely related words, to describe a noun. Since their order can usually be rearranged, you should use commas.

This delicious, tasty dish was cooked by my father.

This delicious tasty dish was cooked by my father.

Another example:

Your daughter is a motivated, creative, imaginative, talented student!

Your daughter is a motivated creative imaginative talented student!

Opinion and fact adjectives

Look at these sentences:

The beautiful large house was built in 1747.

My sister prepared this delicious creamy mushroom pasta dish.

We can differentiate two types of adjectives:

• Fact adjectives (large, creamy, mushroom, pasta in the examples above). Fact adjectives provide factual information about size, color, age, texture, etc.
• Opinion adjectives (beautiful, delicious in the sentences above). Opinion adjectives tell us what someone thinks of somebody or something.

Generally, opinion adjectives go before factual adjectives. As a result, they cannot be rearranged.

I love that fantastic green car.

I love that green fantastic car.

Usually (but not always) we place fact adjectives in this order:

1. size
2. age
3. color
4. Where is it from?
5. What is it made of?

Thus, we say:

• a small metal screwdriver (1 and 5)
• a tall 19-year-old Russian girl (1, 2, and 4)
• large green Italian house (1, 3 and 4)

Pairing adjectives and nouns

Adjectives in English are placed in front of nouns; that is, we say "the young girl" (not "the girl young"). Sometimes, the adjective and the noun that follows become a unit (semantically speaking), as in:

The large computer desk is made of wood.

These wonderful Thai beaches are irresistible.

Since those adjectives cannot be rearranged, no comma.

Coordinate and cumulative adjectives

We can also differentiate between coordinate and cumulative adjectives:

• Coordinate adjectives are equally important, and its order is interchangeable.
• Cumulative adjectives are not equally important. They need to appear in a specific order.

We separate coordinate adjectives with commas.

3. More Examples

Examples where commas are required:

• I didn't enjoy the insipid, tasteless soup.
• I hate dealing with these complicated, intricate problems.
• She is a kind, wise woman.
• The long, narrow path along the east bank invites you to explore and discover more.
• The intelligent, talented young teacher solved the scientific problem.
• Mary is a healthy, strong girl.
• John is a resourceful, reliable boy.
• He is an impertinent, difficult child who doesn't want to go to school.
• Albert is a relaxed, calm person.
• The mean, greedy, selfish man didn't want to help me.

No comma:

• My brother bought an astonishing yellow car.
• My girlfriend has a long black hair.
• Her sister needed a large computer desk, so she bought it this morning.
• My friend is a tall German guy who can speak five languages.
• Try this delicious big hamburger.
• I didn't enjoy the first two years of college: bad roommates, bad classes, bad relationships, etc.
• She'll be on vacation for the next few weeks.
• My parents live in a small blue house down the street.
• My uncle has a huge pear tree.
• She bought one of those small laptop computers with a built-in camera.

4. Conclusion

Deciding whether to place a comma between two adjectives is not always easy for non-native speakers. This strategy, however, will help you punctuate them correctly:

1. If you can reorder the adjectives, place a comma between them.
2. If you are still not sure:
   • Add a comma between two adjectives when:
     • Using three or more colors (e.g., "blue, green and black skirt")
     • Using synonyms (e.g., "talented, intelligent student")
   • Avoid the comma when:
     • Combining opinion and fact adjectives (e.g., "beautiful young girl")
     • An adjective and a noun become a unit. For example, "laptop computer" can be considered a single unit, so we say "light laptop computer".