The +421 country code connects calls to Slovakia, a landlocked country of 5.4 million people in Central Europe. Slovakia split from the Czech Republic in 1993 (the "Velvet Divorce"), and the two countries still share deep cultural ties. Bratislava, the capital, sits on the Danube River just 60 kilometers from Vienna, making it one of the closest pairs of capital cities in the world.
If you see a phone number starting with +421, it originates from Slovakia. The country uses 9-digit subscriber numbers and has a trunk prefix of 0 that you drop when dialing from abroad.
Quick answer: Dial +421 followed by 9 digits. Mobile numbers start with 9. Landlines use area codes (2 for Bratislava, 55 for Košice). Drop the leading 0 used in domestic calls when dialing from abroad.
How to call Slovakia: quick reference
Slovakia uses the international exit code 00 for outgoing calls, but most callers outside Slovakia just need the +421 prefix. Drop the domestic trunk prefix 0 before the area code or mobile prefix.
| Calling from | Dialing format |
|---|---|
| US/Canada mobile | +421 [local number] |
| US/Canada landline | 011-421-[local number] |
| UK | 00-421-[local number] |
| Australia | 0011-421-[local number] |
| Germany | 00-421-[local number] |
| France | 00-421-[local number] |
Understanding Slovakia phone numbers
Slovak phone numbers are 9 digits long after the +421 country code. The system distinguishes mobile and landline numbers by their leading digits.
Mobile numbers
Mobile numbers start with 9 and follow the format +421 9XX XXX XXX (9 digits total). The second and third digits identify the carrier: 0x for O2, 1x for Orange, 4x/5x for Telekom. In practice, number portability means these prefixes no longer reliably indicate the current carrier.
Landline numbers
Landlines use geographic area codes. Bratislava has the shortest area code (2), giving it 8 local digits: +421 2 XXXX XXXX. Other cities use 2-digit area codes with 7 local digits: +421 XX XXX XXXX.
Area codes
| City | Area code | Example format |
|---|---|---|
| Bratislava | 2 | +421 2 XXXX XXXX |
| Košice | 55 | +421 55 XXX XXXX |
| Prešov | 51 | +421 51 XXX XXXX |
| Žilina | 41 | +421 41 XXX XXXX |
| Banská Bystrica | 48 | +421 48 XXX XXXX |
| Nitra | 37 | +421 37 XXX XXXX |
| Trnava | 33 | +421 33 XXX XXXX |
| Trenčín | 32 | +421 32 XXX XXXX |
Mobile carriers in Slovakia
Slovakia has three mobile network operators covering most of the country.
Slovak Telekom
Owned by Deutsche Telekom, Slovak Telekom is the incumbent operator with the largest 4G/5G network. They also operate the fixed-line infrastructure inherited from the state telephone monopoly. Mobile numbers typically start with +421 94x or +421 95x.
Orange Slovensko
Part of the Orange Group, Orange Slovensko has the largest mobile subscriber base in the country. They were the first operator in Slovakia (originally Globtel, rebranded in 2002). Mobile numbers historically start with +421 91x or +421 90x (before porting).
O2 Slovakia
The newest of the three, O2 entered the market in 2007 and positioned itself as a budget-friendly alternative. They have strong coverage in urban areas and along highways. Numbers historically start with +421 94x or +421 95x, though porting has shuffled things around.
MVNOs
Several virtual operators run on these networks, including 4ka (on O2's network, operated by SWAN) and Tesco Mobile (on O2's network). They typically offer lower prices with fewer frills.
Don't confuse +421 with nearby codes
The +421 code sits near several other Central European codes that are easy to mix up.
| Code | Country | How to tell apart |
|---|---|---|
| +420 | Czech Republic | Slovakia's closest neighbor and former partner. Off by just one digit. Czech numbers are 9 digits with no trunk prefix. |
| +43 | Austria | Borders Slovakia to the west. Austrian numbers start with +43 and use area code 1 for Vienna. |
| +36 | Hungary | Borders Slovakia to the south. Large Hungarian-speaking minority in southern Slovakia, so calls between the two are common. |
| +48 | Poland | Borders Slovakia to the north. Polish numbers are 9 digits after +48. |
The most common mistake is mixing up +420 (Czech Republic) and +421 (Slovakia). Before the 1993 split, both countries shared +42. When they separated, Slovakia got +421 and the Czech Republic took +420.
Time zone considerations
Slovakia uses Central European Time (CET, UTC+1) in winter and Central European Summer Time (CEST, UTC+2) from late March to late October.
| Your location | Time difference | Best calling window |
|---|---|---|
| US East Coast (EST/EDT) | +6 hours | 8 AM - 12 PM your time (2 PM - 6 PM Slovakia) |
| US West Coast (PST/PDT) | +9 hours | 7 AM - 10 AM your time (4 PM - 7 PM Slovakia) |
| UK (GMT/BST) | +1 hour | 9 AM - 8 PM your time |
| Australia (AEST/AEDT) | -9 hours | 5 PM - 10 PM your time (8 AM - 1 PM Slovakia) |
| Japan (JST) | -8 hours | 4 PM - 10 PM your time (9 AM - 3 PM Slovakia) |
Slovakia shares the same time zone as its neighbors Czech Republic, Austria, Hungary, and Poland, so cross-border calls within Central Europe don't require time zone math.
Communication in Slovakia
Business hours
Standard business hours are 8 AM to 4 PM or 9 AM to 5 PM, Monday through Friday. Government offices often close at 3 PM on Fridays. Lunch breaks between 12 PM and 1 PM are still common, and some smaller businesses may not answer phones during that window.
Communication style
Slovaks tend to be direct in phone conversations. Business calls get to the point quickly. When calling someone you don't know, start with "Dobrý deň" (good day). Many younger Slovaks and business professionals speak English, but older generations in rural areas may only speak Slovak. In southern Slovakia, Hungarian is widely spoken as a first language.
Network quality
Slovakia has reliable mobile and fixed-line infrastructure. 4G LTE covers over 95% of the population, and 5G is expanding in Bratislava and Košice. Call quality on VoIP services like CallSky is generally excellent over Slovak mobile data or WiFi connections. Rural mountainous areas in the north (Tatras region) may have weaker signals.
The Slovakia diaspora
Where they went
An estimated 300,000+ Slovaks live abroad, with the largest communities in the Czech Republic (the most natural destination given shared language and history), the UK (a popular post-EU-accession destination), Germany, and Austria. The US has a historic Slovak-American community of over 700,000 people with Slovak ancestry, concentrated in Pennsylvania, Ohio, and New Jersey, dating back to steel mill immigration in the late 1800s.
Why they call
Many Slovaks working in the UK, Germany, or Czech Republic call family back home weekly. The calls tend to cluster around Sunday afternoons and weekday evenings. The Slovak-American community, now several generations deep, calls less frequently but still maintains connections during holidays (Christmas, Easter) and name days, which Slovaks celebrate similarly to birthdays. Bratislava's proximity to Vienna also means many Slovaks commute across the border for work, creating daily cross-border calling patterns.
Dialing examples
Calling a mobile phone in Slovakia
To call a Slovak mobile number 0912 345 678 from abroad, drop the leading 0 and dial: +421 912 345 678. From a US landline: 011 421 912 345 678.
Calling a landline in Bratislava
To call a Bratislava landline 02 1234 5678 from abroad, drop the 0 and dial: +421 2 1234 5678. From a UK phone: 00 421 2 1234 5678.
Calling a landline in Košice
To call a Košice landline 055 123 4567 from abroad, drop the 0 and dial: +421 55 123 4567. From an Australian phone: 0011 421 55 123 4567.
Calling within Slovakia
For domestic calls, keep the trunk prefix 0. Dial 0912 345 678 for mobiles or 02 1234 5678 for Bratislava landlines. You always dial the full number including the 0, even for local calls.
Common mistakes to avoid
Mixing up +420 and +421
This is the single most common error. +420 is the Czech Republic, +421 is Slovakia. They shared +42 before 1993, and the codes are still confused constantly. Double-check before dialing.
Keeping the trunk prefix 0
Inside Slovakia, all numbers start with 0 (e.g., 0912 for mobile, 02 for Bratislava). When calling from abroad, drop that 0. Dial +421 912... not +421 0912... The extra zero will cause the call to fail.
Wrong digit count
All Slovak numbers are 9 digits after +421. Bratislava landlines look different (1-digit area code + 8 local digits) from other cities (2-digit area code + 7 local digits), but the total is always 9. If you have more or fewer digits, something is wrong.
Confusing Hungarian-speaking areas
Southern Slovakia has a large Hungarian-speaking population. If someone gives you a phone number while speaking Hungarian, make sure it starts with +421 (Slovakia) and not +36 (Hungary). The person may live in Slovakia but have cultural ties to Hungary.
Prefer calling over WiFi? See our guide to the best apps for WiFi calling.
Frequently asked questions (FAQ)
What country uses the +421 code?
Slovakia. The +421 country code has been assigned to Slovakia since 1993, when Czechoslovakia split into the Czech Republic (+420) and Slovakia (+421).
How many digits are in a Slovak phone number?
9 digits after the +421 country code. This applies to both mobile and landline numbers. Domestically, numbers are 10 digits including the trunk prefix 0.
What is the difference between +420 and +421?
+420 is the Czech Republic and +421 is Slovakia. Before the 1993 Velvet Divorce, both countries shared +42. The codes differ by a single digit, which causes frequent mix-ups.
Do I need to drop the 0 when calling Slovakia from abroad?
Yes. The leading 0 is a trunk prefix used only for domestic calls. When dialing from abroad with +421, skip the 0 entirely. For example, if the local number is 0912 345 678, dial +421 912 345 678.
How much does it cost to call Slovakia?
With CallSky, calls to Slovak landlines start at $0.01/min (Economy) or $0.05/min (Premium). Mobile calls start at $0.19/min (Economy) or $0.16/min (Premium). No subscription required.
For more Central European dialing guides, see Czech Republic (+420), Austria (+43), or Hungary (+36). Or browse the full country codes directory.