What Is GeoIP

GeoIP is the umbrella term for technologies that estimate geographic location from an IP address. It is widely used by websites to determine a visitor's country or region and to tailor content accordingly.

The country, region, city, ISP, and AS number displayed on the IP Check-san homepage are all retrieved using a GeoIP database. Simply by visiting IP Check-san, you can instantly see which country and region your IP address is associated with and which ISP you are connecting through.

The underlying principle is straightforward. IP addresses on the internet are allocated to ISPs and organizations by Regional Internet Registries (RIRs). By cross-referencing this allocation data with the physical locations of ISP connection points, it is possible to estimate an approximate geographic location from an IP address. That said, this mechanism has inherent limitations - it is important to understand that "IP address" does not equal "exact street address."

How GeoIP Databases Work

A GeoIP database is essentially a lookup table that maps IP address ranges to geographic information. It is built from the following data sources:

  • IP address allocation records from RIRs (Regional Internet Registries): managed by five RIRs - ARIN (North America), RIPE NCC (Europe), APNIC (Asia-Pacific), LACNIC (Latin America), and AFRINIC (Africa)
  • Location data for ISPs and data centers
  • BGP (Border Gateway Protocol) routing information: data showing which network paths IP address blocks traverse
  • User feedback and correction reports
  • Location data from Wi-Fi access points and mobile base stations

How MaxMind GeoLite2 Works

IP Check-san uses the MaxMind GeoLite2 database. MaxMind is the leading GeoIP database provider, offering the free GeoLite2 and the paid GeoIP2. GeoLite2 is updated twice a week, reflecting IP address reassignments and ISP changes.

The GeoLite2 database stores location information for each IP address CIDR block (e.g., 203.0.113.0/24). During a lookup, the system identifies the CIDR block that contains the target IP address and returns the location data associated with that block. Because of this design, all IP addresses within the same CIDR block return the same location information.

Other Major Providers

  • IP2Location: offers high-accuracy location databases with detailed data geared toward commercial use
  • DB-IP: a GeoIP service with both free and paid tiers, employing proprietary data collection methods
  • ipinfo.io: an API-based GeoIP service known for its real-time responsiveness

With the growing adoption of IPv6, GeoIP databases have been expanding their IPv6 coverage. However, because IPv6 address allocation structures differ from IPv4, location accuracy for IPv6 tends to be more variable. ISPs acquire vast IPv6 address blocks in bulk, making fine-grained regional classification within those blocks more difficult.

GeoIP Accuracy and Limitations

GeoIP accuracy varies significantly depending on the level of granularity. The belief that "GeoIP can pinpoint your exact address" is a common misconception - in reality, it only indicates an ISP's connection point or the center of a region. Unlike GPS, which uses satellite signals to determine precise coordinates, GeoIP relies on database lookups and is inherently approximate. For a deeper understanding of how IP-based geolocation works, books on IP geolocation and networking offer thorough technical explanations.

Country-Level Accuracy

Country-level accuracy is very high at 95–99%, correctly identifying the country for the vast majority of IP addresses. According to MaxMind's official data, GeoIP2's country-level accuracy exceeds 99.5%. However, misidentification can occur when ISPs near national borders use IP address blocks assigned to a neighboring country.

Region and City-Level Accuracy

City-level accuracy is around 50–80%, with errors of several tens of kilometers possible. This variation stems from how ISPs allocate IP addresses. Major ISPs manage large IP address blocks covering wide areas, so the actual user location and the ISP's registered location can differ significantly.

For example, if a user living in a rural area uses an ISP headquartered in a major city, GeoIP may identify their location as that major city. This happens because the ISP registers the IP address block's location as its headquarters address.

Common Cases Where Accuracy Decreases

  • Mobile networks: mobile carriers use IP address blocks covering wide areas, so the carrier's registered location is often returned rather than the base station's position. City-level accuracy drops significantly compared to fixed-line connections
  • Via VPN or proxy: the VPN server's location is displayed, producing results unrelated to the user's actual position. GeoIP results during a VPN connection reflect the country and city of the connected server
  • CGNAT (Carrier-Grade NAT) environments: a setup where the ISP shares a single global IP address among many users. Under CGNAT, a wide range of users share the same IP, so location information is aggregated to the ISP's representative location. As of 2024, the majority of mobile connections and some fixed-line connections operate under CGNAT
  • Corporate networks: the headquarters' IP address is used, which may differ from the actual location of branch offices or remote workers
  • Satellite internet (e.g., Starlink): IP addresses unrelated to the ground location may be assigned. In Starlink's case, the ground station's location is returned as the GeoIP result
  • Via cloud services: IP addresses from AWS or Google Cloud regions are used, so the physical location of the server is returned

Accuracy Improvement Trends in 2024–2025

GeoIP providers are working on improving accuracy using machine learning. By combining network topology analysis with real-time routing data, accuracy improvements are progressing, particularly for mobile connections. MaxMind implemented updates to improve GeoIP2's city-level accuracy in 2024, reporting improvements in the Asia-Pacific region.

GeoIP Use Cases

Content Localization

GeoIP is used to automatically switch languages and currencies based on a visitor's country. For example, an e-commerce site might serve Japanese with yen pricing for visitors from Japan, and English with dollar pricing for visitors from the United States. GeoIP is just one of several signals websites use for this purpose - for a broader look at how sites detect your preferred language, see our article on why websites know your language.

Regional Restrictions: Geo-Blocking

Video streaming services and similar platforms use GeoIP to permit access only from specific countries due to licensing agreements. Netflix and Amazon Prime Video offering different content libraries by country is a classic example of GeoIP-based geo-blocking.

Fraud Detection and Security

GeoIP is used to detect logins from unusual countries and flag potential unauthorized access. Online banking and e-commerce sites commonly require additional authentication for access from unfamiliar locations. It is also combined with firewalls to block access from specific countries entirely.

Ad Targeting

GeoIP is used to display region-specific advertisements. For locally focused businesses, GeoIP-based ad delivery is a cost-effective approach.

Regulatory Compliance

GeoIP is used to restrict service availability based on the laws of specific countries (e.g., online gambling regulations, data processing restrictions under data protection laws).

GeoIP and Privacy

GeoIP-based location estimation raises privacy concerns:

  • An approximate residential area can be estimated from an IP address alone
  • ISP information reveals which internet service is being used
  • An AS number may allow the user's affiliated organization to be inferred

However, GeoIP cannot determine an individual's exact home address or name. The information remains at the "approximate region" level. The fear that "GeoIP will reveal my home address" is a technically unfounded misconception.

Under the GDPR (EU General Data Protection Regulation) and Japan's Act on the Protection of Personal Information, IP addresses may be treated as personal data or equivalent. As privacy regulations tighten worldwide from 2024 onward, careful handling of GeoIP data is increasingly important. Consulting a guide to data privacy compliance can help website operators navigate these evolving requirements. Website operators are expected to establish appropriate privacy policies regarding the collection and use of GeoIP data.

GeoIP misidentification can also cause real-world problems. For instance, if you are actually in Japan but are identified as being overseas, you may be unable to view content on streaming services or may trigger security alerts on online banking. In such cases, you can contact your ISP or submit a correction through MaxMind's GeoIP location correction form.

GeoIP Information Available on IP Check-san

The IP Check-san homepage displays the following GeoIP information associated with your IP address in real time:

  • Country name and flag: the country to which your IP address is allocated
  • Region and city: regional information based on the ISP's connection point
  • ISP name: your Internet Service Provider
  • AS number: the identification number of your Autonomous System
  • Latitude and longitude: estimated coordinates (displayed on a map)

Practical Examples

  • Verify that GeoIP results change to the VPN server's country when connected to a VPN
  • Confirm that your ISP information is displayed correctly
  • Check how closely the displayed city matches your actual location and experience GeoIP accuracy firsthand
  • Combine with a DNS leak test to comprehensively verify that your VPN's anonymity is maintained

How to Hide Your Location

The following methods can help you avoid GeoIP-based location estimation:

  • Use a VPN: the VPN server's location is displayed instead, hiding your actual position. However, if a DNS leak occurs, your real location may still be exposed even while using a VPN
  • Use the Tor browser: the exit node's location is displayed. The trade-off is a significant reduction in connection speed
  • Route through a proxy server: the proxy's location is displayed. However, traffic may not be encrypted

When connected to a VPN, GeoIP results change to reflect the VPN server's country. For example, connecting from Japan to a US-based VPN server will cause GeoIP to identify you as being in the United States. However, even with a VPN, your actual location may be exposed in the following cases:

  • DNS leak: DNS queries are sent outside the VPN tunnel, and your actual IP address is recorded by the ISP's DNS server
  • WebRTC leak: the browser's WebRTC functionality exposes your local IP address
  • VPN connection drops: when the VPN connection is temporarily interrupted, communication occurs using your real IP address

Check your IP address and location on IP Check-san to verify that your location is properly hidden when connected to a VPN.

Actions You Can Take Right Now

After reading this article, try the following steps:

  • Visit the IP Check-san homepage and check your GeoIP information (country, region, city, ISP)
  • Compare the displayed city name with your actual location to experience GeoIP accuracy firsthand
  • If you use a VPN, compare GeoIP results with and without the VPN connection
  • Compare GeoIP results between mobile and Wi-Fi connections to observe accuracy differences by connection type
  • If GeoIP results differ significantly from reality, submit a correction through MaxMind's correction form

Related Glossary Terms

GeoIP A technology that estimates approximate geographic location (country, region, ci…