The minimum age to rent a car in Ontario is 21 years old. However, rental agencies typically apply an additional "young driver fee" for renters under 25, which can range from $10 to $30 per day depending on the location and rental company. Some rental companies may also impose restrictions or additional requirements for drivers under 25 years old.

Summary of Age Requirements in Ontario

• Minimum age: 21 years old
• Young driver surcharge: Applies to renters under 25
• Additional fees or restrictions may apply for renters aged 21 to 24

This is the general standard across most Ontario car rental companies.