How to Calculate the Ideal Aisle Width for Your Warehouse

In warehouse design, calculating the appropriate aisle width is an indispensable part of warehouse design.

Whether you're working with traditional racking systems or more advanced automated solutions, the right aisle configuration directly impacts your facility’s performance.

This article offers a comprehensive guide to help you determine the optimal aisle width for your warehouse, focusing on the most effective use of space.

Why Aisle Width Matters

Aisle width is the measurement of the open space between racks, allowing for the movement of material handling equipment (MHE) such as forklifts and pallet shuttles. It is not just a matter of convenience; the aisle width affects multiple aspects of your warehouse’s operation, including:

• Storage capacity: Wider aisles provide more room for equipment but take up valuable storage space. Narrower aisles maximize storage, but require more specialized equipment.
• Order fulfillment speed: Proper aisle width can help optimize the flow of goods, speeding up retrieval and order picking processes.
• Safety and maneuverability: Adequate space ensures that MHE can navigate aisles safely and efficiently without risking damage to products or equipment.

When determining aisle width, several factors must be considered, including the type of racking system used, the dimensions of pallets, the equipment available, and the operational flow of goods.

Key Factors in Determining Aisle Width

The width of your warehouse aisles will depend on several variables:

    1. Forklift Equipment: The dimensions and type of forklifts in use are the primary factors in defining aisle width. Larger, traditional forklifts require wider aisles to turn and navigate, while narrow-aisle equipment like VNA (Very Narrow Aisle) trucks can operate in smaller spaces.

    2. Pallet Size: The size of your pallets—typically measured in length and width—affects how much space is needed for maneuvering and accessing inventory.

    3. Racking System: The type of storage system also dictates aisle width. For example, pallet racks, shuttle systems, and automated storage and retrieval systems (ASRS) each have specific requirements for aisle space.

    4. Forklift Turn Radius: Forklifts require a certain amount of space to complete a full turn. This radius must be factored in when calculating aisle width, especially for machines that need to pivot and maneuver in tight spaces.

    5. Maneuverability: Aisles should allow enough space for forklifts to operate smoothly and safely. A minimum clearance of 12 inches is typically recommended for optimal maneuverability.

    6. Racking Depth and Height: Deeper racking systems, such as deep-reach pallet racks, may require additional aisle space to accommodate the increased depth.

Different Aisle Width Categories

Based on the type of equipment and operational needs, aisle widths generally fall into one of three categories:

• Wide Aisles (>10'): This configuration allows for the use of large forklifts and other material handling equipment, providing ample space for maneuvering. However, it reduces the overall storage density.
• Narrow Aisles (9'): Narrow aisles offer a good balance between accessibility and storage density, making them ideal for most traditional warehouses.
• Very Narrow Aisles (<9'): Used with specialized equipment such as VNA trucks or automated storage systems, very narrow aisles maximize storage space but require more advanced machinery to operate safely.

Choosing the Right Aisle Width for Your Facility

Selecting the ideal aisle width requires a careful analysis of your specific needs. Below is a general guide for determining aisle width based on the type of forklift and racking system in use.

Forklift Aisle Width Requirements

Racking System Aisle Width Requirements

• Selective Pallet Racking: Typically requires 10-12 feet for reach trucks and 12-16 feet for counterbalanced forklifts.
• Pushback Pallet Racking: Requires wider aisles, typically around 12-14 feet, due to the need for equipment to navigate deep lanes.
• Drive-in Racking: This system requires even wider aisles (up to 14 feet) because forklifts need to drive into the racking system to store and retrieve pallets.
• Automated Storage and Retrieval Systems (ASRS): Aisle width for ASRS is generally more compact, around 6-8 feet, as these systems are designed for very narrow aisle configurations and are operated automatically.

How to Calculate Aisle Width for Your Warehouse

To calculate aisle width, you must account for several measurements, including forklift head length, pallet size, maneuverability space, and racking system depth.

Basic Formula for Aisle Width Calculation:

    1. Forklift Head Length: The distance from the back of the truck to the front of the load backrest.

    2. Pallet Length: Measure the length of the pallet, typically around 48 inches for standard pallets.

    3. Pallet Overhang: Add 6-12 inches for pallet overhang, especially if your pallets are oversized.

    4. Maneuverability Space: Add at least 12 inches to ensure the forklift can navigate smoothly without hitting the racks or walls.

Example Calculation

Let’s assume the following:

• Forklift head length: 6 feet
• Pallet length: 4 feet
• Pallet overhang: 6 inches
• Maneuverability space: 12 inches

The calculation would be:

Aisle Width=Forklift  Head  Length+Pallet  Length + Pallet  Overhang + Maneuverability

Aisle  Width=6  feet + 4  feet + 0.5  feet + 1 foot = 11.5  feet

For this scenario, you would need at least 11.5 feet of aisle width.

Optimizing Aisle Width with Automated Solutions

Automated solutions like ASRS, shuttle systems, and autonomous mobile robots (AMRs) can significantly reduce the required aisle width by utilizing more compact equipment. These systems are designed for high-density storage and retrieval and often operate in very narrow aisles, as they don’t require the same turning radius as traditional forklifts.

Automated systems such as unit load ASRS and miniload ASRS are typically used in environments with high inventory turnover, where maximizing storage capacity and retrieval speed is essential. These systems allow for extremely tight aisle configurations, which would be impractical with conventional equipment.

For instance, a pallet shuttle system can work in aisles as narrow as 6 feet, improving space utilization without compromising operational efficiency. Similarly, autonomous mobile robots (AMRs) can navigate these smaller aisles, helping to reduce aisle width without sacrificing speed or reliability.

Table: Recommended Aisle Width for Different Racking Systems and Equipment

Conclusion

Careful planning is essential to strike the right balance between storage space and operational efficiency. Consult with material handling experts and forklift manufacturers to ensure that your aisle width calculation aligns with your warehouse goals.

Proper aisle width ensures that your warehouse operates smoothly, supports your inventory management strategy, and contributes to the success of your business.