IP Address Lookup: What It Actually Reveals, How Accurate It Is, and When It Fails

In 2016, Joyce Taylor called the police again. For the third time that year, strangers had shown up at her rented farmhouse near Potwin, Kansas, demanding to know why she'd been sending them threatening emails. Federal marshals had come too. So had the IRS. Someone from the FBI once sat in her driveway for hours.

The farmhouse sat at 39.8333 N, -98.5855 W — the geographic center of the contiguous United States. And the company MaxMind, which operates one of the world's largest IP geolocation databases, had been using those exact coordinates as the default location for every IP address it couldn't precisely place. Over 600 million IP addresses pointed at this one house.

Taylor eventually sued MaxMind. They changed their default to the center of a lake. But the incident reveals something most "IP lookup" guides never mention: the entire system is built on probabilistic guesses, not precise coordinates. Understanding what IP lookup actually does — and where it breaks — matters more than any set of instructions.

What an IP Address Lookup Actually Returns

When you enter an IP address into a lookup tool, the system queries a geolocation database that maps IP address ranges to physical-world data. Here's what you get back, roughly in order of reliability:

Source: MaxMind published accuracy data

Highly reliable: Country, ISP name, ASN (Autonomous System Number), connection type (cable, cellular, corporate), and whether the IP belongs to a hosting provider or VPN.

Usually reliable: State or region, timezone, continent.

Often approximate: City (could be 10-50km off), postal code, latitude/longitude coordinates. These are educated guesses based on where the ISP has registered that IP block, not GPS-level precision.

Never revealed: The person's name, physical street address, email, or identity. An IP address identifies a network connection, not a human being.

The Accuracy Problem Nobody Talks About

The numbers above (99.8% country, 80% state, 66% city) come from MaxMind's own reporting. Independent research paints a different picture.

A 2023 IEEE study compared multiple commercial geolocation databases against each other and found an average pairwise distance discrepancy of 620 kilometers between providers. That means if one database says an IP is in Chicago, another might place it in Nashville. Both are "correct" within their own system; neither may be the actual location.

An APNIC study testing free-tier databases found country accuracy as low as 77.5% — significantly below the 99%+ numbers that commercial databases advertise for their paid products.

Where Accuracy Breaks Down

• Mobile IPs: Cellular carriers route traffic through regional gateways. Your phone might geolocate to a city 100km away from where you're actually standing.
• Satellite internet (Starlink): Early Starlink assignments often geolocated to the ground station location, not the user's dish. Starlink has been improving this, but it remains inconsistent.
• Developing regions: Accuracy outside North America and Western Europe drops significantly. WhatIsMyIPAddress reports only 55% city-level accuracy outside the US and Europe.
• VPNs and proxies: The lookup returns the VPN server's location, not the user's. This is by design — it's the entire point of a VPN.
• Recently reassigned IP blocks: When ISPs buy IP ranges from other regions (IPv4 transfers), the geolocation databases can take weeks or months to update.

The CGNAT Problem: When One IP Address Is Shared by Hundreds

Here's something that fundamentally changes what an IP lookup means, and almost every guide ignores it.

CGNAT (Carrier-Grade NAT) allows ISPs to share a single public IP address among hundreds — sometimes thousands — of customers. T-Mobile, one of the largest US carriers, uses CGNAT for its 130+ million customers. It's even more prevalent in Africa and Asia where IPv4 addresses are scarcer.

When you look up a CGNAT IP address, you're seeing the shared gateway's location, not any individual user's location. Cloudflare's research identified over 200,000 CGNAT IP addresses and found that these IPs get rate-limited 3x more often than non-CGNAT IPs — not because they're more malicious, but because their traffic looks suspicious due to the volume of different users sharing the address.

CGNAT IPs have a mean bot rate of 7%, compared to 13.1% for non-CGNAT IPs. Yet they get rate-limited far more often because the aggregate traffic from hundreds of users looks anomalous. — Cloudflare Research, 2025

The IPv4 Address Market: Why IP Addresses Are Traded Like Real Estate

There are only 3.687 billion routable IPv4 addresses in existence. As of January 2026, only 3.9 million remain in the global Available Pool. The rest are allocated.

This scarcity created a secondary market. Since 2012, 342 million IPv4 addresses have been transferred between organizations — 9.3% of the total delegated space. In 2025 alone, 33 million addresses changed hands across 5,619 transactions.

Why does this matter for IP lookup? When IP address blocks change ownership — a European company sells a /16 block to a North American ISP — geolocation databases need time to update. During that window, an IP lookup might show the wrong country entirely. The more transfers happen, the more stale data exists in any given database.

IPv6 Changes the Game

IPv6 offers 340 undecillion addresses (3.4 × 10³⁸). Global adoption is now around 45-49% of internet traffic. France leads at ~80%, Germany at ~75%, India at ~74%, and the US recently crossed the 50% threshold.

IPv6 theoretically allows more precise geolocation because each device can have its own unique address. But IPv6 adoption is uneven — China reports 865 million "active IPv6 users" while Google measures Chinese IPv6 traffic at under 10% — and geolocation databases have less historical data for IPv6 ranges than IPv4.

What Courts Say: IP Address Does Not Equal Identity

This is the most practically important thing to know about IP lookup, and the one thing almost every guide skips.

Multiple US federal judges have ruled that an IP address does not identify a specific person. The reasoning is straightforward: shared connections (roommates, families, open WiFi), CGNAT, VPNs, and compromised devices all mean the subscriber isn't necessarily the user.

The EFF has documented extensive case law on this. In copyright infringement cases, courts have repeatedly held that "being the registered subscriber of an infringing IP address does not create a reasonable inference that the subscriber is also the infringer."

This matters for anyone thinking about using IP lookup for investigations, fraud detection, or security. An IP address is a starting point for investigation, not proof of identity. To connect an IP to a person, law enforcement needs a subpoena to the ISP for subscriber records — and even then, the subscriber may not be the person who used the connection.

Practical Uses: Where IP Lookup Actually Works Well

Despite the limitations, IP lookup is a cornerstone of internet infrastructure. The key is knowing what it's good at.

Fraud Detection

Juniper Research projects $362 billion in online payment fraud losses between 2023 and 2028. IP geolocation is a frontline defense: if a credit card billing address is in Texas but the transaction IP geolocates to Romania, that's a fraud signal. Not proof — the cardholder could be traveling — but a meaningful data point in a risk scoring model.

Content Delivery and Compliance

Streaming services use IP geolocation for licensing compliance (different content catalogs per country). E-commerce sites show local currency and shipping options. News sites comply with GDPR by detecting EU visitors. These are high-value, country-level decisions where 99.8% accuracy is more than sufficient.

Security Monitoring

If your server logs show login attempts from 47 different countries in one hour, IP lookup helps you see the pattern. You don't need city-level precision — country-level is enough to identify credential stuffing attacks, unusual access patterns, or compromised accounts being accessed from unexpected regions.

Network Troubleshooting

When a user reports connectivity issues, looking up their IP reveals the ISP, ASN, and connection type. This immediately narrows the troubleshooting scope: is it a mobile carrier issue? A specific hosting provider? A known problematic network?

How to Actually Look Up an IP Address

There are several approaches depending on what you need:

1. Web-based lookup tool — The simplest method. Enter an IP at our IP Address Lookup tool and get instant results including location, ISP, ASN, timezone, and an interactive map. No registration required.
2. Command-line tools — whois queries the RIR database for registration info. nslookup or dig resolves hostnames. traceroute shows the network path. These are useful for network administrators who need raw data.
3. API access — For programmatic lookups, our geolocation API returns JSON/XML with location, ISP, ASN, connection type, and more. Useful for integrating IP intelligence into applications, fraud systems, or analytics platforms.
4. Email header analysis — If you have a suspicious email, the headers contain the sender's IP chain. Our email header analyzer extracts and geolocates each IP in the routing path.

What an IP Lookup Cannot Tell You

It's worth being explicit about what you won't find:

• The person's name or identity — An IP maps to a network, not a human.
• Their exact physical address — City-level at best, often just the ISP's regional hub.
• What they were doing — An IP tells you where, not what or why.
• Whether they're at that location right now — IP assignments can change. The person might have moved, or the ISP might have reassigned the address.
• Anything about VPN users' real location — You'll see the VPN server, not the person behind it.

If you need to understand how IP geolocation databases work at a technical level — the six data sources they combine, the RIPE Atlas measurement network, and why databases disagree — our deep-dive article covers that in detail.

For tracking who clicks a specific link, an IP logger captures visitor IPs automatically and plots them on an interactive map. And if you're investigating suspicious emails specifically, our guide on how to track an IP address covers that workflow step by step.

Frequently Asked Questions

Can someone find my exact address from my IP?

No. An IP lookup reveals your approximate city and ISP, not your street address. Only your ISP can connect your IP to your physical address, and they require a legal subpoena to disclose that information.

Is it illegal to look up someone's IP address?

No. IP address information is publicly available network data. Looking up an IP address is legal and widely practiced for security, analytics, and network administration. However, using IP data to harass or stalk someone may violate other laws.

Why does my IP address show a different city?

IP geolocation maps to the location where your ISP registered that IP block, which may be a regional hub rather than your actual city. Mobile connections often show the carrier's gateway city. This is normal and expected — city-level accuracy is about 66% for US IPs.

Does a VPN hide my real IP from lookups?

Yes. When using a VPN, any IP lookup will show the VPN server's IP address and location, not yours. This is the primary function of a VPN — to replace your public IP with the server's. Our VPN detector can identify when an IP belongs to a known VPN provider.