What’s the Plural of Formula: Understanding Variations in English

Formula, Formulas, Formulae — See the Pattern

Look at these words. Can you see what happens?

• one formula → two formulas or formulae
• one antenna → two antennas or antennae
• one vertebra → two vertebras or vertebrae
• one larva → two larvas or larvae

Did you see the pattern? These words all come from Latin. In Latin, words ending in -a change to -ae for the plural. So formula becomes formulae.

You can also use the normal English rule and just add -s to get formulas. Both are correct, and formulas is the one you will hear most often in everyday English.

When to Use Formulas and When to Use Formulae

Both words mean the same thing. But people use them in different places.

Use formulas when:

• You are writing in everyday English → “The book has simple formulas for cooking.”
• You are talking about baby milk → “The shop sells different baby formulas.”
• You want to keep things simple → “He tried several formulas before he found the right one.”

Use formulae when:

• You are writing about science or math → “The formulae in this chapter are important for the exam.”
• You want to sound more formal or academic → “Several chemical formulae were tested in the lab.”

Easy way to remember: If you are not sure, use formulas. It works everywhere and everyone will understand you.

Real-Life Examples With Formula, Formulas, and Formulae

• The baby needs a new formula because she does not like this one. (one — baby milk)
• We learned three new formulas in math class today. (more than one — math rules)
• The scientist tested several formulae in the lab. (more than one — science context)
• What is the formula for success? (one — a method or plan)
• The chemistry book lists all the formulae you need for the exam. (more than one — formal/academic)

You are doing great. Now let’s look at the mistakes many learners make with this word.

Two Mistakes to Avoid With Formula

Even native speakers sometimes pause before writing the plural of formula — so if you get confused, you are not alone. The Latin ending makes it tricky, but once you learn it, it sticks.

How to remember: The Latin plural already has the ending built in: formula becomes formulae. Do not add an extra -s after that. If you want to use the English way, just add -s to the original word: formula + s = formulas.

Other words that follow this pattern: antenna → antennae, vertebra → vertebrae, larva → larvae, nebula → nebulae, alumna → alumnae.

Test Yourself: Formula, Formulas, or Formulae?

Choose the correct answer for each sentence. Click Check to see if you are right.

Keep Going — You Are Building Something

You just learned that formula becomes formulas or formulae. That is one more Latin plural you will never get wrong again.

But here is something interesting. The word vertebra also comes from Latin and follows the same -a → -ae pattern. So the plural should be simple, right? But what happens when doctors, teachers, and everyday people all use different versions of the plural? And is “vertebras” even a real word?

Next lesson: What Is the Plural of Vertebra?

Sources

Etymology of formula, Online Etymology Dictionary.