Picking & Packing
Picking and packing are the core activities in warehouse order fulfillment. Picking involves retrieving items from storage locations to fulfill customer orders, while packing involves preparing those items for shipment in appropriate containers with protective materials. Together, these operations determine fulfillment speed, accuracy, and cost.
Modern warehouses use a combination of picking methods, technologies, and packing strategies to optimize throughput while maintaining high accuracy rates. The right approach depends on order profiles, SKU velocity, facility layout, and customer requirements.
Picking Methods
Warehouses employ different picking strategies based on order volume, SKU count, and operational priorities. Most facilities use a combination of methods across different zones or shifts.
Picking Method Selection Guide
The following decision tree helps determine the optimal picking method based on operational characteristics:
Picking Method Comparison Matrix
| Method | Picks/Hour | Best Order Volume | Complexity | Training | Investment | Best For |
|---|---|---|---|---|---|---|
| Discrete | 80-120 | <100/day | Low | Easy | Low | B2B, custom orders, low volume |
| Batch | 120-180 | 100-1,000/day | Medium | Moderate | Low-Medium | E-commerce with SKU overlap |
| Zone | 150-250 | 500-5,000/day | High | Moderate | Medium | Large warehouses, diverse SKUs |
| Wave | 120-200 | 1,000-10,000/day | High | Moderate | Medium | Deadline-driven operations |
| Cluster | 200-350 | 1,000-10,000/day | Medium | Moderate | Medium-High | Small-item e-commerce |
Discrete Picking (Pick-and-Pass)
Discrete picking assigns one picker to one order at a time. The picker travels through the warehouse collecting all items for a single order before moving to the next.
Advantages:
- Simple to implement and train
- Clear accountability (one picker per order)
- No order consolidation required
- Ideal for low-volume, high-value orders
Disadvantages:
- High travel time per order
- Lower picks per hour
- Inefficient for high-volume operations
Best for: B2B orders, custom configurations, hazardous materials, high-value items requiring individual attention.
Batch Picking
Batch picking groups multiple orders together. A picker collects the same SKU for multiple orders in a single trip, then sorts items by order during consolidation.
Advantages:
- Reduces travel time (one trip for multiple orders)
- Higher picks per hour than discrete picking
- Works well with similar order profiles
Disadvantages:
- Requires sorting/consolidation step
- Risk of mixing orders during sort
- Batch size optimization needed
Best for: E-commerce with similar SKUs across orders, moderate SKU velocity, facilities with dedicated consolidation areas.
Optimal batch size balances travel reduction against sorting complexity. Most operations use batches of 4-12 orders depending on SKU overlap and cart capacity.
Zone Picking
Zone picking divides the warehouse into zones, with dedicated pickers assigned to each zone. Orders flow through zones sequentially, with each picker adding their zone's items.
Advantages:
- Pickers develop zone expertise
- Reduced congestion (dedicated zones)
- Parallel processing across zones
- Scalable with volume
Disadvantages:
- Requires zone balancing (workload distribution)
- Handoff coordination between zones
- Partial orders travel through facility
Best for: Large facilities, high SKU count, operations with distinct product categories.
Zone Picking Variants
| Variant | Description | When to Use |
|---|---|---|
| Sequential zone | Order passes through zones in sequence | Multi-category orders, traditional layout |
| Parallel zone | All zones pick simultaneously, consolidate at end | High volume, balanced zones |
| Zone-batch hybrid | Batch picking within each zone | Combines zone expertise with batch efficiency |
Wave Picking
Wave picking schedules picking activities in time-based waves aligned with shipping cutoffs, carrier pickups, or production schedules. Waves can use any picking method (discrete, batch, zone).
Advantages:
- Aligns picking with downstream operations (packing, shipping)
- Balances workload across shifts
- Enables priority order handling
- Optimizes labor deployment
Disadvantages:
- Requires wave planning and release logic
- Orders may wait for wave start
- Complexity in multi-wave environments
Best for: Operations with shipping deadlines, multiple carrier pickups, facilities coordinating picking with packing capacity.
Waves are typically defined by: carrier pickup time, shipping service level (same-day, next-day), order priority, destination zone, or product category.
Cluster Picking (Pick-to-Cart)
Cluster picking uses multi-compartment carts where a picker collects items for multiple orders simultaneously, placing each item directly into the correct order compartment.
Advantages:
- Very high picks per hour
- No consolidation step needed
- Reduced travel time
- Real-time order completion
Disadvantages:
- Cart capacity limits order count
- Complex routing to avoid congestion
- Requires specialized equipment
Best for: E-commerce with small orders (1-8 items), high volume, facilities with wide aisles for carts.
Picking Workflow
The standard picking process follows these steps:
Pick List Optimization
Modern WMS systems optimize pick lists by:
- Shortest path routing: Minimizes travel distance through warehouse
- Product slotting: Places fast-movers near packing area
- Pick density: Groups nearby items together
- Traffic management: Avoids picker congestion in narrow aisles
Picking Technologies
RF Scanning (Barcode-Directed Picking)
Pickers use handheld RF scanners to receive pick instructions and confirm picks by scanning location and SKU barcodes.
Workflow:
- Scan location barcode to confirm correct pick location
- Display shows SKU, description, quantity
- Scan item barcode to confirm correct SKU
- Enter quantity picked
- System confirms and advances to next pick
Advantages:
- High accuracy (99.9%+ with dual scanning)
- Audit trail for every pick
- Real-time inventory updates
- Works with any warehouse layout
Disadvantages:
- Requires both hands (scanner + item)
- Slower than light-directed systems
- Barcode quality dependent
Best for: General-purpose picking, facilities with diverse SKU types, operations requiring strong audit trails.
Voice Picking
Pickers wear headsets connected to a voice-directed system. The system speaks pick instructions, and pickers confirm using voice commands and check digits.
Workflow:
- System: "Go to aisle 12, position 4, level B"
- Picker navigates to location
- System: "Pick 3 units of item ending in 7-2-9"
- Picker: "7-2-9" (confirms location check digit)
- Picker: "3" (confirms quantity)
Advantages:
- Hands-free and eyes-free operation
- Higher picks per hour than RF scanning
- Safer (forward vision maintained)
- Works in cold storage and harsh environments
Disadvantages:
- Requires quiet environment or noise-canceling headsets
- Check digit system adds step
- Less effective for complex SKU descriptions
Best for: High-volume operations, grocery/beverage distribution, cold storage, facilities with experienced picking staff.
Pick-to-Light
Pick-to-light uses illuminated displays mounted at each pick location. Lights indicate which items to pick and the quantity.
Workflow:
- Picker scans order barcode to start
- Lights illuminate at all required locations
- Display shows quantity at each location
- Picker retrieves items, presses button to confirm
- Light turns off, picker moves to next lit location
Advantages:
- Fastest picking method (300+ picks/hour possible)
- Minimal training required
- Very high accuracy
- Ideal for piece picking
Disadvantages:
- High capital cost for light installations
- Best for small SKU count in dense zones
- Fixed infrastructure (difficult to reconfigure)
Best for: E-commerce split-case picking, pharmacy, parts distribution, facilities with stable SKU layouts.
Put-to-Light
Put-to-light is the reverse of pick-to-light. Pickers batch-collect items, then use lights to direct placement into order containers.
Workflow:
- Picker batch-picks a SKU from storage
- Scans SKU at put wall
- Lights illuminate at all orders needing that SKU
- Displays show quantity for each order
- Picker places items, confirms at each location
Advantages:
- Extremely fast sortation (500+ units/hour)
- Efficient for many orders with overlapping SKUs
- Reduces travel time
- Ideal for small-item e-commerce
Disadvantages:
- Requires put wall infrastructure
- Limited by number of order positions
- Best for high-order volume
Best for: E-commerce with small items, high order volume with SKU overlap, operations using wave picking.
Picking Technology Comparison
| Technology | Picks/Hour | Accuracy | Capital Cost | Best For |
|---|---|---|---|---|
| RF Scanning | 80-120 | 99.5-99.9% | Low | General purpose |
| Voice Picking | 120-180 | 99.5-99.9% | Medium | Case picking, cold storage |
| Pick-to-Light | 200-350 | 99.9%+ | High | Piece picking, dense zones |
| Put-to-Light | 300-500 (sort) | 99.9%+ | High | E-commerce sortation |
| Manual (paper lists) | 40-80 | 95-98% | None | Low-volume operations |
Most modern warehouses use multiple technologies: voice for case picking in bulk storage, pick-to-light for piece picking in forward pick zones, and RF scanning for slow-movers.
Packing Operations
After picking, items move to packing stations where they are prepared for shipment.
Packing Station Design
A well-designed packing station includes:
Essential components:
- Work surface: 4-6 ft wide, 30-34" height for ergonomics
- Box storage: Flat boxes stacked by size for quick access
- Packing materials dispenser: Tape, bubble wrap, air pillows, dunnage
- Scale: For weight verification and shipping label generation
- Computer/scanner: WMS access, label printing
- Label printer: Thermal printer for shipping labels
- Waste/recycling bin: For packing material waste
Layout principles:
- Materials within arm's reach
- Box sizes arranged by frequency (most common closest)
- Scale positioned to avoid lifting packed boxes
- Printer accessible without blocking work surface
Packing Workflow
Cartonization (Box Selection)
Cartonization is the process of selecting the optimal box size for a given set of items. Manual selection leads to oversized boxes, excess dunnage, and higher shipping costs.
Manual cartonization:
- Packer visually estimates box size needed
- Often results in 20-30% excess box volume
- Inconsistent across packers
Automated cartonization:
- WMS/TMS runs 3D bin-packing algorithm
- Considers item dimensions, weight, fragility, stacking rules
- Recommends smallest box that fits all items
- Calculates exact dunnage needed
Benefits of automated cartonization:
- 15-25% reduction in box costs
- 10-20% reduction in dimensional weight charges
- Faster packing (no decision time)
- Reduced dunnage waste
- Consistent packing across all orders
Cartonization systems integrate with WMS during order release or at packing station. Real-time cartonization at packing allows last-minute order changes.
Packing Materials
| Material Type | Purpose | Common Forms | When to Use |
|---|---|---|---|
| Corrugated boxes | Primary container | RSC (Regular Slotted Container), various sizes | All shipments |
| Bubble wrap | Cushioning for fragile items | Rolls, pre-cut sheets, bubble mailers | Glass, electronics, ceramics |
| Air pillows | Void fill, light cushioning | Inflatable pillows, various sizes | Void fill in oversized boxes |
| Paper dunnage | Sustainable void fill | Crinkle paper, kraft paper rolls | Eco-friendly cushioning |
| Foam inserts | Custom protection | Die-cut foam, foam-in-place | High-value or precision items |
| Packing peanuts | Void fill | Expanded polystyrene or biodegradable | Filling large voids (decreasing use) |
| Corrugate pads | Layer separation, cushioning | Flat pads, various sizes | Protecting flat items, layer dividers |
| Edge protectors | Corner/edge protection | Cardboard or plastic angles | Protecting corners, pallet edges |
| Stretch wrap | Pallet stabilization | Plastic film rolls | Pallet wrapping, bundling |
| Tape | Sealing | Hot melt, water-activated, reinforced | Box sealing (3" minimum overlap) |
Dunnage selection criteria:
- Item fragility: Glass requires bubble wrap; books need minimal protection
- Void space: Use air pillows or paper to prevent shifting
- Sustainability goals: Recyclable/biodegradable materials preferred
- Cost: Balance protection against material cost
- Carrier requirements: Some carriers specify minimum cushioning standards
Box Sizes and SKU Rationalization
Most warehouses stock 5-12 standard box sizes to balance flexibility against inventory complexity.
Common box size strategies:
| Strategy | Box Count | Approach | Best For |
|---|---|---|---|
| Minimal | 3-5 sizes | Small, Medium, Large, XL | Low SKU variation, simple products |
| Standard | 8-12 sizes | Tiered sizing across dimensions | E-commerce, diverse SKUs |
| Custom | 15+ sizes | Product-specific boxes | Branded unboxing, specialty items |
Box selection criteria:
- Carrier dimensional weight tiers (avoid crossing thresholds)
- Product protection requirements
- Branding and customer experience
- Pallet utilization (boxes should tessellate on pallets)
Quality Control in Picking & Packing
Quality checks prevent errors from reaching customers. Checkpoints can be inserted at multiple stages:
Pre-Pack Quality Checks
| Check Type | Method | What It Catches | Accuracy Impact |
|---|---|---|---|
| Pick verification | Scan SKU during pick | Wrong item picked | 99%+ |
| Location verification | Scan location before pick | Wrong location accessed | 99%+ |
| Quantity verification | Count confirmation prompt | Quantity errors | 98%+ |
| Consolidation check | Scan items into order tote | Missing items, mixed orders | 99%+ |
Pack Verification
| Check Type | Method | What It Catches | Implementation |
|---|---|---|---|
| Weight verification | Compare packed weight to expected | Missing/extra items | Scale at each station |
| Visual inspection | Packer reviews items before boxing | Damaged items, wrong items | Manual, every order |
| Barcode scan | Scan each item during packing | Wrong items | Adds 10-15 sec/order |
| Dimensioning | Automated dimension capture | Oversized boxes, DIM weight errors | Automated systems |
| Random audit | QC staff inspects sample of packed orders | Systemic errors | 5-10% of orders |
Industry data shows shipping errors cost $15-50 per incident (return shipping, restocking, customer service, replacement shipment). A 1% error rate in a 10,000 order/day operation costs $1.5M-5M annually.
Error prevention best practices:
- Use vision systems or weight verification at packing
- Implement mandatory scan-to-pack for high-error SKUs
- Provide packing images or instructions for complex items
- Track error rates by picker and provide retraining
- Use color-coded pick locations for look-alike SKUs
Performance Metrics
Picking Metrics
| Metric | Definition | Target Range | How to Calculate |
|---|---|---|---|
| Picks per hour | Units picked per labor hour | 80-300 (method dependent) | Total picks ÷ picker hours |
| Lines per hour | Order lines picked per labor hour | 25-80 | Order lines ÷ picker hours |
| Travel time % | % of shift spent traveling | <40% | Travel time ÷ total shift time |
| Pick accuracy | % of picks with correct SKU and quantity | >99.5% | Correct picks ÷ total picks |
| Order cycle time | Time from order release to pick complete | <30 min (standard) | Average time per order |
Packing Metrics
| Metric | Definition | Target Range | How to Calculate |
|---|---|---|---|
| Packs per hour | Orders packed per labor hour | 30-80 | Orders packed ÷ packer hours |
| Pack accuracy | % of shipments with no packing errors | >99% | Correct shipments ÷ total shipments |
| Box utilization | % of box volume filled by items | 65-85% | Item volume ÷ box volume |
| Dunnage cost per order | Average cost of packing materials | $0.50-2.00 | Total dunnage cost ÷ orders |
| Dimensional weight efficiency | % of shipments at or below actual weight | >70% | Non-DIM shipments ÷ total shipments |
WERC benchmarks show top-quartile operations achieve 150+ picks/hour with 99.8%+ accuracy using voice or light-directed systems. Bottom quartile averages 60-80 picks/hour with 98.5% accuracy using paper or basic RF.
Best Practices
Picking Best Practices
- Optimize slotting: Place A-items (fast movers) in golden zone (waist to shoulder height) near packing
- Use forward pick zones: Keep high-velocity SKUs in piece-pick areas to reduce case-break travel
- Implement directed picking: Let WMS optimize routes, don't allow free-form picking
- Monitor picker productivity: Track picks/hour by picker, identify training needs
- Reduce picker travel: 50-60% of pick time is travel; layout and slotting are critical
- Use exception handling: Flag short-picks, damaged inventory for immediate resolution
- Batch intelligently: Optimize batch size based on SKU overlap and cart capacity
- Zone balance: Monitor zone workload distribution, rebalance when imbalanced
Packing Best Practices
- Standardize box sizes: Limit to 8-12 sizes, rationalize annually based on order profiles
- Implement cartonization: 20%+ savings in materials and shipping costs
- Verify weight: Catch errors before shipment (missing items, wrong items)
- Ergonomic stations: Reduce repetitive strain injuries with proper height, layout
- Material accessibility: Keep high-use materials within arm's reach
- Train on fragile items: Provide specific packing instructions for breakable SKUs
- Monitor dunnage usage: Track cost per order, identify waste
- Automate label application: Reduce labeling errors with print-and-apply systems
- Pre-kit common configurations: For repeat orders, pre-pack items in ready-to-ship kits
- Continuous improvement: Review error root causes weekly, implement corrective actions
Technology Evolution
Automation in Picking & Packing
| Technology | Description | Throughput Impact | Implementation Cost |
|---|---|---|---|
| Goods-to-Person (GTP) | AutoStore, Shuttle systems bring items to picker | 3-5x productivity | $2M-10M+ |
| Autonomous Mobile Robots (AMRs) | Robots carry shelves or bins to pickers | 2-3x productivity | $500K-2M |
| Automated packing systems | Robotic case erectors, box formers | 2-4x packs/hour | $200K-1M per line |
| Print-and-apply labelers | Automated label printing and application | Eliminates labeling errors | $20K-50K per station |
| Vision systems | Cameras verify contents before sealing | 99.9%+ accuracy | $30K-100K per station |
| Collaborative robots (cobots) | Assist with heavy lifting, repetitive tasks | 10-30% productivity | $50K-150K per unit |
Automation investments typically target 2-3 year payback through labor reduction and error prevention. GTP systems suit operations with 5,000+ orders/day and stable SKU profiles.
Resources
| Resource | Description | Link |
|---|---|---|
| MHI Picking & Packing Solutions | Material Handling Institute guides on automation and best practices | mhi.org |
| WERC Warehouse Metrics | Warehousing Education and Research Council benchmarking data | werc.org |
| Honeywell Voice Solutions | Voice-directed picking technology and implementation guides | honeywellaidc.com |
| Kardex Picking Methods Guide | Comparison of picking strategies and technologies | kardex.com |
| ShipHawk Cartonization Tools | Packing optimization and dimensional weight guides | shiphawk.com |
Related Topics
- Labels & Barcoding — barcode standards for pick verification
- Warehouse Zones — zone layout impacts picking efficiency
- Receiving & Putaway — proper putaway enables efficient picking
- Inventory Management — inventory accuracy is critical for pick success
- Shipping Labels — final step after packing