diff --git a/includes/providers/class-open-router-pricing.php b/includes/providers/class-open-router-pricing.php
index 89b58e8..09e4c60 100644
--- a/includes/providers/class-open-router-pricing.php
+++ b/includes/providers/class-open-router-pricing.php
@@ -114,8 +114,8 @@ class PRAutoBlogger_OpenRouter_Pricing {
 	 * @return float Estimated cost in USD.
 	 */
 	public function estimate_cost( string $model, int $prompt_tokens, int $completion_tokens ): float {
-		// OpenRouter `:free` suffix models cost nothing.
-		if ( ':free' === substr( $model, -5 ) ) {
+		// OpenRouter free models: the `openrouter/free` router and any `:free` suffix model.
+		if ( 'openrouter/free' === $model || ':free' === substr( $model, -5 ) ) {
 			return 0.0;
 		}