Czech Republic phone number validator
How the phone number format works
- Format
- Czech Republic phone number in national or international (+420) format
- Example
- +420601123456
Things to watch for
- Accepts national or international (E.164, e.g. +420...) format
- Validated with Google's libphonenumber; confirms the number is possible/valid for this country, not that it is currently assigned or reachable
^[+]?[0-9 ()\-]{6,}$A Czech phone number is 9 digits long in national form, with no trunk prefix to drop — unlike Germany or France next door, Czechia’s numbering plan never adds a leading 0, so the national number and the digits after +420 are identical. Mobile numbers start with 6 or 7 (601 123 456), while landlines start with 2 through 5 depending on region (2 for Prague). That absence of a trunk digit is the one habit that trips up people used to other European formats.
How this validator works
Enter the number as 9 plain digits (601123456) or with the country code (+420601123456) — this tool checks digit count and prefix range against Czechia’s real numbering plan using Google’s libphonenumber library, entirely in your browser, nothing sent to a server. Because there’s no trunk zero to strip, converting a Czech number to +420 format is just concatenation: no digit is added or removed, which also means a validator can’t quietly fix a wrong number by dropping a zero — the 9 digits themselves have to be right from the start.
What a pass doesn’t tell you
A pass confirms the 9 digits match a plausible Czech mobile or landline pattern — it doesn’t confirm the SIM is active or the landline is connected. Prague’s shared 2-prefix, for instance, covers a huge range of fixed and VoIP numbers, and format alone can’t distinguish a live line from a disconnected one.
Scope: catch a missing digit or a wrong prefix before a Czech number goes into a shipping form or SMS platform — not a substitute for a carrier lookup.
Content last reviewed 2026-07-07.
phone number FAQ
Does a Czech phone number use a trunk prefix like 0 that gets dropped for +420?
No. Czechia's 9-digit numbers don't use a leading 0 at all, domestically or internationally — a mobile number is 601123456 in both national dialing and after +420, with no digit added or removed.
How can I tell a Czech mobile number from a landline by its first digit?
Mobile numbers start with 6 or 7; landlines start with 2 through 5, with 2 covering Prague. Both are 9 digits total, so the leading digit — not the length — is what separates them.
Does a valid format check mean the Czech number is reachable?
No. It confirms the 9 digits match a real Czech mobile or landline pattern, not that the line is currently active or assigned to anyone — that requires a carrier-side lookup, which this free tool doesn't perform.