To determine the correct belt size, you'll need to:
1. Identify the compressor being bypassed: Determine if it's the A/C compressor, power steering pump, or another component.
2. Visually inspect the belt routing: With the compressor disconnected, carefully trace the path the belt would take around the remaining pulleys.
3. Measure the existing belt (if possible): If you have the original belt, measure its length. This provides a starting point.
4. Consult a parts store or online retailer: Provide them with your vehicle's year, make, and model, and specify which compressor is being bypassed. They can then look up the appropriate belt size using their databases. You might even be able to show them a picture of your routing.
5. Use a belt measuring tool: Auto parts stores often have tools to accurately measure the belt length needed for your specific routing. This is the most accurate method.
Do not simply guess the belt size. Using an incorrectly sized belt can lead to slippage, premature belt wear, and potentially damage to other engine components.