diff --git a/src/api/providers/openrouter.ts b/src/api/providers/openrouter.ts
index 31300b868b..26019ce34a 100644
--- a/src/api/providers/openrouter.ts
+++ b/src/api/providers/openrouter.ts
@@ -48,8 +48,13 @@ interface CompletionUsage {
 	}
 	total_tokens?: number
 	cost?: number
+	is_byok?: boolean
 }
 
+// with bring your own key, OpenRouter charges 5% of what it normally would: https://openrouter.ai/docs/use-cases/byok
+// so we multiply the cost reported by OpenRouter to get an estimate of what the request actually cost
+const BYOK_COST_MULTIPLIER = 20
+
 export class OpenRouterHandler extends BaseProvider implements SingleCompletionHandler {
 	protected options: ApiHandlerOptions
 	private client: OpenAI
@@ -164,7 +169,7 @@ export class OpenRouterHandler extends BaseProvider implements SingleCompletionH
 				// and how to best support it.
 				// cacheReadTokens: lastUsage.prompt_tokens_details?.cached_tokens,
 				reasoningTokens: lastUsage.completion_tokens_details?.reasoning_tokens,
-				totalCost: lastUsage.cost || 0,
+				totalCost: (lastUsage.is_byok ? BYOK_COST_MULTIPLIER : 1) * (lastUsage.cost || 0),
 			}
 		}
 	}