Series context: This is Part 7 of the E-commerce Order Allocation series. The distance matrix built here feeds directly into the OR-Tools VRP solver in Part 6.
The Invisible yet Most Expensive Bottleneck in E-commerce Routing
Answer-first: For 1 warehouse + 100 delivery stops, you need 10,201 pairwise distances. Self-hosting GraphHopper or OSRM on a $20/month VPS delivers this in under 50ms per batch — completely free. Using Google Maps Distance Matrix API for the same workload costs $510/day. This guide shows you exactly when to use which tool, with Docker setup and production Python code.
For any VRP (Vehicle Routing Problem) solver to find the optimal delivery route, it needs to know the exact cost between every pair of stops — this is the distance matrix. For 1 warehouse + 100 orders (101 points), that is 101 × 101 = 10,201 pairs. Choosing the wrong tool for this step can cost $510/day in API fees or cause multi-second latency spikes under load.
1. As the Crow Flies: The Haversine Formula
