The verb to cost · Conjugation
Past Continuous of cost
The answer: was / were costing
B1
An action in progress in the past, often interrupted.
Quick answer
The Past Continuous of the verb to cost is was / were costing.
Example: I was costing a lot of money when the phone rang.
Full conjugation in the Past Continuous
| Pronoun | Form |
|---|---|
| I | was costing |
| You | were costing |
| He / She / It | was costing |
| We | were costing |
| You (pl.) | were costing |
| They | were costing |
Common mistakes to avoid
1. You was / They was ❌
Use was only with I, he, she and it. Use were with you, we, they and plural nouns: you were costing, my friends were costing. You always takes were, even when you talk to one person.
2. Always add -ing
In the Past Continuous, the verb after was or were always ends in -ing: they were costing. Without -ing, they were cost is not the Past Continuous, and the meaning changes. Without was or were, they costing is wrong.
3. I was knowing ❌
State verbs (know, understand, want, need, like) are not normally used in the continuous. In the past, use the Past Simple: I knew the answer, not I was knowing the answer.
Practice quiz
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Frequently asked questions
How do you conjugate cost in the Past Continuous?+
Use was or were (the past of be) + the -ing form costing. Use was with I, he, she and it. Use were with you, we and they: I was costing, they were costing.
When do you use the Past Continuous of cost?+
Use it for an action in progress at a moment in the past: At 8 o'clock, I was doing my homework. It often describes a long action, and a short action interrupts it: I was having a shower when the phone rang. The short action is in the Past Simple.
What is the difference between I cost and I was costing?+
I cost (Past Simple) is a finished action, seen as one complete event. I was costing (Past Continuous) is the same action in progress, like the background of a story. Compare: I did my homework and I was doing my homework when you called.
Is it when or while with the Past Continuous?+
Both are possible, but they usually go with different actions. While goes with the long action, in the Past Continuous: While I was walking home, it started to rain. When usually goes with the short action, in the Past Simple: I was walking home when it started to rain.
How do you make the negative and the question of cost in the Past Continuous?+
Negative: add not after was or were: I wasn't costing, they weren't costing. Question: put was or were before the subject: Were you costing…?, Was she costing…? Do not add did: Did you were costing? is wrong.
Related pages: cost Past Continuous
Pages on a similar topic or with a similar use, so you can keep exploring.
Updated on 12 November 2026 by the Big Challenge teaching team. Every year, more than 500,000 students across Europe take part in our English contest, created in 1999. Our teaching approach →
The Big Challenge · Updated on 12 November 2026 · Source: www.thebigchallenge.com/bl/academy/learn-english/verbs/cost/past-continuous
© The Big Challenge. Copying allowed for classroom use. Every year, more than 500,000 students across Europe take part in our English contest, created in 1999.
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More forms of the verb to cost are coming soon.