Prioritize throughput metrics (orders/hour, picks/line), on‑time shipping rate, inventory accuracy, and dock turn time. Ensure the 3PL supports API or EDI integration with your WMS/ERP, real‑time tracking, exception workflows, and a clear SLA for peak volumes.

Location drives zone distribution and carrier chargeable weight; sites closer to major highways, rail yards, or ports reduce transit days and LTL spend. Use a nodal approach: position fast‑moving SKUs closer to demand centers and slow movers in lower‑cost storage to optimize carrying costs.

Confirm reverse logistics processes, returns disposition SLAs, inspection and refurbishment capacity, multi‑channel pick/pack workflows, and marketplace integration. Also verify label compliance, batching for sellers, and reporting for chargebacks and reconciliations.

Key drivers: transportation lane density, zone count, storage rates, labor overtime, and cross‑dock fees. Mitigate by inventory repositioning, zone skipping, consolidating shipments, negotiating carrier accessorials, and using seasonal labor flex rather than permanent hires.

Assess the 3PL's peak capacity history, temp labor pools, overflow agreements, and secondary site options. Review disaster recovery plans, alternate carrier contracts, and technology for rapid SKU onboarding to ensure continuity during spikes or supply chain interruptions.