What Is IP Geolocation? How It Works, Accuracy & Use Cases

Introduction

IP geolocation (also called GeoIP) is the process of estimating the real-world location of an Internet-connected device, such as its country, region, city, and network, from its IP address. An IP geolocation lookup maps an IP address to location and network data so a website or app can know roughly where a visitor is connecting from, without asking them.

Leading companies on the Internet have relied on IP geolocation for many years to understand their customers and visitors better. Today, most businesses access this data through an IP geolocation API or an IP geolocation database, and use it for content localization, analytics, compliance, and fraud prevention.

In this article, we'll cover what IP geolocation is, how it works, how accurate it is, the difference between an IP geolocation database and an API, and the most common use cases.

What is an IP Address?

An Internet Protocol address (IP address) is a numerical label such as 192.0.2.1 that is assigned to a device connected to a computer network that uses the Internet Protocol for communication.

The main functions of an IP address are identifying the host, or more specifically its network interface, and providing the location of the host in the network, which makes it possible to establish a path to that host. Its role has been characterized as follows: "A name indicates what we seek. An address indicates where it is. A route indicates how to get there."

What are the use cases of IP Geolocation?

Many systems use IP geolocation services to benefit from the information they provide. Some of the most common use cases are:

• Geomarketing: Providing web content or products that are popular or useful in the visitor's specific location.
• Content Localization: Personalizing web content according to the geographic location of the visitor. For example, showing the Arabic version of a website to visitors from Arab countries, or the UK version of a website to visitors from the United Kingdom.
• Analytics: Understanding where a website's or app's audience comes from, so teams can plan marketing, pricing, and infrastructure.
• Criminal investigations and compliance: Banks, software vendors, and other online businesses in the US and elsewhere became subject to strict "know your customer" (KYC) laws imposed by the USA PATRIOT Act, the Bank Secrecy Act, the US Treasury Department's Office of Foreign Assets Control (OFAC), and other regulators in the US and Europe from the early twenty-first century. These laws are intended to prevent money laundering, financing of terrorist organizations, and trading with sanctioned countries. When it is possible to identify the true location of online visitors, geolocation helps banks avoid taking part in transfers of funds for illicit purposes.
• Fraud Prevention: Online retailers and payment processors use IP geolocation to detect possible payment fraud by comparing the user's IP location with the billing address on the card or the shipping address provided. A mismatch, such as an order placed from one country using a card issued in another, is a strong indicator of potential fraud. Fraud teams also check whether the IP address belongs to a VPN, proxy, Tor exit node, or hosting provider, because fraudsters often use these to hide their real location. You can learn more about Greip's IP location intelligence and VPN & proxy detection.
• Enforcing Policies: Applying GDPR or other terms and policies according to the visitor's location, as well as geo-restricting content, licensing, or sanctioned regions.

IP geolocation is not designed to be a harmful tool for tracking down a specific person or device. It is a helpful way for organizations to personalize their websites and apps for their users according to their needs, and to enforce policies for their visitors and users.

These services are used in legitimate and important business practices across many industries, including banking, telecommunications, travel, hospitality, entertainment, and law enforcement. Banks, for example, help prevent phishing attacks, money laundering, and other security breaches by checking the user's location as part of the authentication process.

How does IP geolocation work?

IP geolocation services estimate the geographic location of a device connected to the Internet. They cannot return the user's exact physical location; they return an approximate location (an estimate).

It is not possible to get the exact real-time location of a device from its IP address, because the Internet Protocol was not designed to identify the physical location of devices. Instead, providers combine many data sources to estimate where an IP address is most likely being used.

Almost all IP geolocation services work by looking up a given IP address in databases that contain location data for IP address ranges. At Greip, as an IP geolocation provider, we go further than a single database: we combine multiple data sources with our own algorithms to get the most accurate and complete data possible for each IP address.

IP geolocation techniques can be classified into two main types [4]:

1. Static techniques

This is the most popular type, used by almost all IP geolocation providers. It relies either on a database that lists IP address ranges with their geographic location data, or on the Domain Name System (DNS) names of nearby routers to geolocate an IP address:

• Database lookup: A database that maps IP address ranges to geographic location information. This information is often gathered from public WHOIS databases, which describe the registrant or assignee of an IP address block. However, WHOIS information can be incomplete, outdated, or inaccurate. Also, if a large block of IP addresses is allocated to a single organization, WHOIS does not show where the individual IP addresses inside that block are actually used. Such databases are difficult to build and maintain, and because Internet service providers regularly reassign IP addresses to their customers, they need to be updated frequently.
• Domain Name System (DNS): An alternative approach that extracts geographic hints from the DNS name of the end host or of nearby routers. Network operators often give routers domain names that include geographic codes (for example, airport or city codes). Identifying these codes on a router close to the target can provide a useful estimate of its location. However, this approach is not always reliable, because not all routers have descriptive names and there is no standard for naming them.

2. Measurement-based techniques

Measurement-based geolocation uses active measurements of round-trip times (RTTs) to a target IP address from machines at known locations. Internet Control Message Protocol (ICMP) echo requests (pings) are used to collect RTT values between pairs of machines. These techniques assume that network delay and physical distance are correlated, so several measurements from different known locations can narrow down where the target is.

This is a simplified description; these techniques are more complex in practice, and we recommend following the references below to learn more about them.

How accurate is IP geolocation?

IP geolocation is an estimate, so its accuracy depends on the level of detail you need and on the type of network behind the IP address:

• Country level vs city level: Country-level results are generally very reliable, because IP address blocks are allocated and routed regionally. City-level results are less precise: an IP address may resolve to the nearest city where the ISP's infrastructure is located rather than the user's actual city, and results can vary between providers.
• VPNs and proxies: When a user connects through a VPN, proxy, or Tor, the IP address shows the location of that server, not the user. This is why serious fraud and compliance checks combine geolocation with VPN & proxy detection.
• Mobile networks: Mobile carriers often route traffic through a small number of gateways, so many users across a large area can share IP addresses that appear to be in one city.
• iCloud Private Relay: Apple's Private Relay hides the user's real IP address and only exposes an approximate region. Learn more in How to Effortlessly Detect iCloud Private Relay in Action.
• Reassigned IP blocks: IP address ranges are regularly sold, transferred, or reassigned between networks and countries. Databases that are not updated frequently can return outdated locations.

Because of these limits, IP location should be treated as a strong signal rather than proof of where a user is. For transactions, it works best combined with other checks; see Using IP Geolocation to Prevent Location Spoofing in Online Transactions.

IP geolocation database vs IP geolocation API

There are two main ways businesses use IP geolocation data:

• IP geolocation database: A downloadable file (for example, CSV or binary) that you host and query on your own servers. It offers very fast local lookups, but you are responsible for downloading updates regularly. If the file is not refreshed often, results become outdated as IP ranges change.
• IP geolocation API: A web service you call with an IP address to get location, network, and often security data in real time, usually as JSON. There is no data to maintain on your side, the data stays up to date, and many APIs also return extra fields such as ASN, ISP, time zone, currency, and VPN/proxy/Tor flags.

For most websites, SaaS products, and fintech or e-commerce platforms, an IP geolocation API is the simpler option, because the data is always fresh and it can be integrated with a single HTTP request. For example, see the Greip GeoIP lookup endpoint documentation.

If you are comparing providers, these guides can help:

• How to Choose the Right IP Geolocation API for Your Business (Free Checklist)
• Free vs Paid IP Geolocation APIs: Which Is Right for Your Fintech Security Stack?

Conclusion

IP geolocation has become an important part of most websites and applications because of the valuable information it provides. Businesses use it to enforce policies like GDPR, personalize content, understand their audience, and protect their systems from fraud and abuse. Just remember that it is an estimate: country-level data is generally reliable, while city-level data and IPs behind VPNs, proxies, mobile networks, or iCloud Private Relay need extra care.

If you want to put this into practice, try the Greip IP Geolocation API with a 3-day free trial that includes 1,000 requests. To see how location data fits into a full fraud workflow, read How to Detect and Mitigate Fraudulent Activities Using IP Geolocation Data.

For more background on IP geolocation and how it works, we recommend the references below.

References

1. Internet geolocation - Wikipedia
2. IP address - Wikipedia
3. What is IP Geolocation and How Does It Work?
4. IP Geolocation in Metropolitan Areas