IP ranges in Czechia

This page lists the IPv4 address blocks registered to organisations in Czechia and checks single addresses. The basics of IP addresses, masks and subnets are in Networks; the other countries are in IP ranges by country.

Czechia in numbers

The 48 countries here hold 725,908,608 IPv4 addresses; Czechia has 9,160,384 in 1,784 blocks, 1.26% of the total, rank 17 of 48. The country just above it is Ireland with 10,010,432 addresses (1.38%), the one just below Ukraine with 9,090,560 addresses (1.25%). There are 1,784 blocks: 1,511 allocated (84.7%) and 273 assigned (15.3%). The oldest block was delegated in 1984 and the newest in 2026; 2019 is the year with the most new blocks. The largest share of the addresses, 5,572,224 of 9,160,384 (60.8%), came in the 2000s. The same RIPE file lists 676 IPv6 prefixes and 715 AS numbers for Czechia.

Check an IP address

Type an IPv4 address. The answer comes from the Sypex Geo database on this server; like every geolocation database it can be wrong, especially about the city.

Where the list comes from

IP addresses are handed out by five regional internet registries. For Czechia the registry is RIPE NCC, which publishes every day which address blocks it has delegated to which country. A block registered in Czechia is usually used there, but not always: a company may use its addresses abroad, and a VPN makes any visitor look like someone else.

The table below is the RIPE file of 2026-10-29: 1,784 blocks with 9,160,384 addresses. The largest block holds 262,144 addresses and starts at 88.100.0.0.

Get the list yourself

Download the statistics file of RIPE NCC:

curl -s -O https://ftp.ripe.net/pub/stats/ripencc/delegated-ripencc-latest

The first line says when it was made; the sixth field is the date:

head -1 delegated-ripencc-latest

2|ripencc|1793314799|167770|19700101|20261029|+0100

Each later line is one block: registry, country, type, first address, number of addresses, date and status. The IPv4 blocks of Czechia, sorted by first address:

awk -F'|' '$2=="CZ" && $3=="ipv4"' delegated-ripencc-latest | sort -t'|' -k1,1V | head -3

ripencc|CZ|ipv4|2.59.220.0|1024|20190327|allocated ripencc|CZ|ipv4|5.1.56.0|2048|20120425|allocated ripencc|CZ|ipv4|5.39.200.0|1024|20180611|allocated

How many blocks, and how many addresses they hold together:

awk -F'|' '$2=="CZ" && $3=="ipv4"' delegated-ripencc-latest | wc -l

1784

awk -F'|' '$2=="CZ" && $3=="ipv4" {s+=$5} END {print s}' delegated-ripencc-latest

9160384

allocated means RIPE gave the block to a provider (a LIR) to hand out further; assigned means it went to an end user directly.

Who owns a block

The statistics name no owners. The RIPE database does: ask it with whois for any address of a block, and look at the lines netname, descr and org:

whois 88.100.0.1

All IPv4 blocks in Czechia

From the RIPE file of 2026-10-29, sorted by address. The last address is the first one plus the size minus one.