Words Ending in -o: Potatoes or Potatos?
Quick Answer
Most everyday words ending in -o add -es: one potato, two potatoes. Newer or shortened words just add -s: photos, pianos, zeros. There is a simple test to tell them apart.
See the Pattern First
Two groups, side by side.
- One potato, two potatoes. One tomato, two tomatoes.
- One hero, two heroes. One volcano, two volcanoes.
- But: one photo, two photos — short for photograph.
- And: one piano, two pianos — borrowed from Italian.
Here is the test that works almost every time: old, common, English-feeling words take -es. Foreign, musical or shortened words take -s.
The Full List
The words with two forms are marked — both are accepted.
| One | Many | One | Many |
|---|---|---|---|
| potato | potatoes | tomato | tomatoes |
| hero | heroes | volcano | volcanoes / volcanos |
| mango | mangoes / mangos | zero | zeros / zeroes |
| concerto | concertos | photo | photos |
| piano | pianos | radio | radios |
Why Food Words Take -es
Potato, tomato and hero have been in English for centuries and feel completely English now. Words that feel native take the fuller -es ending.
Photo, piano and radio are either shortened forms or recent borrowings. English treats them lightly and just adds -s. So the ending tells you something about the word’s age — which is a nice thing to notice.
Old and English: -es. New or foreign: -s.
The Two Safe Ones
For a few words, both spellings are correct and no one will mark you wrong:
- mangoes or mangos
- volcanoes or volcanos
- zeros or zeroes
If you are in an exam and unsure, choose -oes for a food or an everyday object. It is right far more often than not.
Mistakes Learners Make (You Are Not Alone)
These are the three that cost marks:
- ✗ two potatos → ✓ two potatoes
- ✗ many heros → ✓ many heroes
- ✗ three photoes → ✓ three photos (photo is short for photograph, so it takes -s)
A famous story: a politician once “corrected” a child’s spelling of potato to “potatoe”. He was wrong, and it followed him for years. Potatoes yes, potatoe no.
Your Turn — Quick Quiz
Five questions. Take your time — the table above is still there if you need it.
1. 1. She bought five ____ for the soup.
2. 2. The firefighters were real ____.
3. 3. I took twenty ____ on holiday.
4. 4. The concert hall has two ____.
5. 5. Which spelling is ALSO acceptable for the plural of mango?
Keep Going
You now have a test that handles -o words without memorising each one.
Next: words ending in -a. One formula, two formulae? Or formulas? This is where science and everyday English pull in opposite directions.
Next lesson: Words ending in -a: formula, antenna, vertebra
Sources
I’m Khamis Maiouf. English is not my first language – I learned it as an adult in the UK, passed Functional Skills Level 2 in English, qualified in Hairdressing at Level 3, and I’m now studying Business at university. For over five years I’ve taught ESOL classes in my community and tutored students through GCSE English. I write every lesson on this site myself, for the learner I used to be.
