F1 drivers weigh themselves after a race primarily for two reasons: to ensure compliance with the minimum weight regulations that include the driver's weight as part of the car, and for health monitoring due to the significant weight loss drivers experience during a race.

Weight Regulations Compliance

• Formula 1 cars have a minimum weight limit, which includes the driver's weight with all safety gear (helmet, race suit, gloves, shoes, etc.).
• Since 2019, drivers must weigh at least 80 kg (increased to 82 kg in 2025) fully equipped. If a driver weighs less than this, ballast must be added to the car to meet the minimum weight.
• Teams and officials weigh drivers after races to confirm they still meet the minimum weight after the physical demands of the race, as failing to meet requirements can result in penalties or disqualification.

Health Monitoring

• Drivers lose 2 to 4 kilograms of body weight during a race due to sweating from intense physical exertion, high cockpit temperatures, and G-forces.
• The weigh-in informs teams and medical staff about the driver's hydration and condition after the race, guiding recovery and ensuring driver health safety.
• Races in hot and humid locations can cause even greater weight loss, highlighting the importance of this measure.

In summary, F1 drivers weigh themselves after races to check they comply with strict weight rules ensuring fair competition, and to monitor their physical well-being after enduring extreme race conditions. This dual purpose is critical for both regulatory fairness and driver safety in the sport.