What Is IP Geolocation and How Does It Work?
IP geolocation maps an IP address to a physical location using databases built from ISP data, BGP routing tables, and active probing.
Every device on the internet has an IP address — a unique identifier assigned by its internet service provider. IP geolocation is the process of mapping that address to a physical location: a country, city, or even a postal code.
How geolocation databases are built
The core of any IP geolocation service is its database. These databases are built from multiple sources:
- RIR delegation files — RIPE, ARIN, APNIC, LACNIC, and AFRINIC publish which IP ranges are allocated to which organizations.
- BGP routing tables — Border Gateway Protocol tables show how traffic flows across the internet, revealing geographic patterns.
- ISP data — Internet service providers know exactly where their customers are. Some share anonymized data with geolocation vendors.
- Active probing — Sending packets to an IP and measuring round-trip latency from multiple known locations triangulates position.
Accuracy expectations
Country-level accuracy is typically 95–99%. City-level drops to 70–85%. Postal code accuracy varies widely — urban areas in Western countries tend to be much more accurate than rural or emerging-market regions.
Mobile IPs are particularly challenging because carriers often route all traffic through a central gateway in a different city from the actual user.
IPv6 vs IPv4
IPv6 geolocation is generally less accurate than IPv4 because IPv6 deployment is newer and the databases have less historical data. Large ISPs are still building out their IPv6 infrastructure, and allocation practices differ from IPv4.
What OpenIPApi adds
Beyond standard database lookups, OpenIPApi runs active probing from 50+ nodes worldwide. This lets us verify whether an IP responds, identify hosting environments, detect proxy behaviors, and refine confidence scores — all updated continuously.