Cost vs. Costed
“Cost” and “costed” can both be correct because they serve different verb senses. The ordinary price/loss sense usually stays “cost” in the past, while “costed” is standard when someone estimates or determines a cost.
Use “cost” for the ordinary past meaning “had a price” or “caused a loss”; use “costed” when the verb means calculated, estimated, or assigned a cost.
Key details
Choose the right form
| Meaning / situation | Form / construction | Decision |
|---|---|---|
| state what price something had | cost | Use the irregular past form “cost.” |
| state that something caused a loss | cost | Use “cost” for the ordinary past-tense loss sense. |
| calculate, estimate, or assign a cost | costed | Use “costed” for the costing/accounting sense. |
Quick tests
Meaning / construction test
Does the past-tense verb simply state a price or loss?
If yes: Use “cost.”
If no: If it means calculated or estimated the cost, use “costed.”
Caveat: Choose by the documented meaning or construction; a different pattern may be valid in a different sentence structure or variety.
Examples
The repair cost $800.
The verb states the price.
The delay cost us two days.
The verb states a loss.
The project was costed before approval.
“Costed” means that its cost was calculated or estimated.
Further guidance
Core difference
Use “cost” for the ordinary past meaning “had a price” or “caused a loss”; use “costed” when the verb means calculated, estimated, or assigned a cost.
Fast Test
If you can paraphrase the verb as “was priced at / required payment,” use “cost.” If you mean “calculated the cost of,” “costed” is the appropriate regular past form.
Sense Boundary
The distinction is semantic, not merely regional: “The repair cost $500” and “The team costed the repair at $500” use different senses of the verb.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
- COST — Merriam-Webster (opens in a new tab)Merriam-Webster · Direct dictionary evidence distinguishing ordinary unchanged cost from costed in the estimating/pricing sense