You should generally change your running shoes every 300 to 500 miles. This mileage range is when the midsole cushioning and overall support typically start to break down, reducing shock absorption and increasing the risk of injury to your feet, legs, and joints. The exact timing depends on factors such as your running style, body weight, running surface, and shoe quality. For example, heavier runners or those running on rough terrain may need to replace shoes closer to 300 miles, while lighter runners on smoother surfaces might get up to 500 miles. In terms of time, casual runners (under 10 miles per week) might replace shoes every 8 to 12 months. Runners covering 10 to 20 miles weekly replace them every 5 to 8 months, half-marathon trainers every 4 to 6 months, and marathon-level runners every 2 to 3 months due to higher mileage and wear. Besides mileage, watch for signs such as worn outsole tread, flattened cushioning, joint pain, discomfort, or sudden difficulty in running. These symptoms indicate your shoes have lost their effectiveness and should be replaced regardless of the exact miles logged. Tracking your mileage via a running app or smartwatch can help manage shoe replacement proactively.