Common English Mistake: Cost or Costed?

I recently made a common English mistake. This was what I said:

• "He bought a house last year. It costed him a lot of money."

What's the mistake? Of course, it's the verb cost, an irregular verb that is conjugated as cost/cost/cost (present/past tense/past participle). Here's the correct sentence:

• He bought a house last year. It cost costed him a lot of money.

In short, if you are describing the amount of money someone paid for something, never write costed. The verb is irregular, and therefore you cannot add ~ed to it.

Cost: Confusion betwee the Present and Past Tense

Because the present simple tense and the past simple tense of the verb cost are the same, this could lead to ambiguity (a lack of clarity). Here is an example:

• The cookies cost a dollar each.

Is this sentence in the present tense, describing a fact (the price of the cookies)? Or is it in the past tense, describing how much you paid for the cookies? The only way to know is through context (the surrounding sentences).

• The cookies cost a dollar each. That's affordable. (The verb is shows we are talking in the present tense.)
• The cookies cost a dollar each, so we bought four. (The verb bought suggests we are talking about the past.)

There are many other verbs that have the same form in the present, past simple, and past participle, so this is nothing new. Here are some common examples:

• hit/hit/hit
• hurt/hurt/hurt
• let/let/let
• put/put/put
• quit/quit/quit
• read/read/read
• shut/shut/shut
• spread/spread/spread

Note: The Word 'Costed' Exists

There is a second, less common meaning of the verb cost. It is a transitive verb that requires an [object].

to cost (out) [something]: to estimate the price of an object.

Costing (out) something is generally done in a business context. If your job is to cost a campaign, you must calculate (estimate) how much money the campaign will require. This is a different meaning of cost, and its use is not common in general English.

Yesterday, he costed (out) a project. (transitive verb)

I hope this page was helpful for you. If you have a question or find a mistake, please leave a comment below.

- Matthew Barton / Creator of Englishcurrent.com (copyright)