I work in the car rental industry in Australia and can tell you. From a car rental perspective. Most don’t care if it’s international. The only thing that we typically need is a credit card(can’t be debit) and a copy of your license that needs a photo of you on it. You may be able to have an additional card if yours doesn’t have an id. Word of warning, if you do have a license that isn’t in English. This will need a translation.

The other piece we typically tell renters, Although we accept it, some countries weirdly enough require the international license. So make sure you check with the local laws. It’s good to check these anyway as road rules may change. For e.g. Italy has different speed limits for different lanes.

this is the case across several companies including EHI (Enterprise, National, Alamo & Redspot), Hertz Group (Hertz & Thrifty), Europcar, ABgroup (Avis & Budget).

Kind Regards,
Car rental guy

TLDR

International driving licenses are accepted everywhere, however, they don’t circumvent other restrictions, like age restrictions. No single national license is accepted everywhere.

Basic understanding

Some countries driving licenses are accepted by others, sometimes reciprocally, but often not. The reason for this is due to the tests that the typical license holder went through and the restrictions their license applies.

For driving in the EU (and the UK) an EU or UK license is required if driving for more than a short visit (something in the order of months). These were standardised with each other and are accepted as one in the same.

For short visits to the UK, all licenses are accepted due to fairly recent relaxations in the regulations to aid with trade and tourism.

US licenses were not accepted until recently as they were considered too simple to obtain (the DMV queues and hassle don’t count for testing your driving competency) and don’t restrict access sufficiently (3.5 tonnes being the limit on a car license in the EU and the UK). Granted, applying for an international license doesn’t test your driving competency, but it was an additional step that if you went through showed competency in another way – checking what you need to do to drive in another country before you get there.

The UK has a helpful form to find out your restrictions, though the information is incomplete: https://www.gov.uk/driving-nongb-licence

Other Restrictions and Requirements

Other restrictions, like age, can result in a normally acceptable license not being sufficient. It’s my understanding that some states allow children to drive from as young as 14 – even with an international license, they would not be allowed to drive in the EU or the UK until they reach the age requirement by the driving country.

There are further exceptions to the above, but generally it’s worth reading up on the destinations driving regulations and requirements. Little things like additional road signs, recovery equipment, and spares can also trip visitors up.

Some other legal requirements for EU countries I drive in that differ from the UK:

• spare bulbs
• breathalysers
• high vis jackets per seat
• warning triangles
• stopping to help broken down vehicles
• lights on in tunnels
• tire chains (and in some countries, no tire chains)
• no radar detectors

Consequences

First, it’s worth noting that you can hire cars, vans, lorries, motorbikes, and other vehicles from most countries without showing your driving license. That does not mean you can drive them. It’s also not to their benefit to try to restrict who can hire, unless the responsibility has been placed upon them by their insurers.

Insurance – insurance is null and void if you aren’t allowed to drive the vehicle. In some countries, this is a criminal offence that could result in prison time. If you’re involved in an accident and found not to have valid insurance, you could face prison time in many more countries.

In some countries, vehicles are confiscated from the drivers for lack of sufficient insurance, or driving without a valid license, along with on the spot fines. This could have knock-on fines from the hire companies.

Summary

Check your license for the destination country, get an international license if necessary, and learn the destinations rules and regulations.

They’re only necessary if local car rental offices say that they’re necessary to rent a car for license holders from your country. For example Avis Japan is very clear that an IDP is mandatory:

You will need your passport and International Driving Permit (IDP), recognized under the Geneva Convention. The IDP must have an expiry date of one year after issue. It will be valid in Japan one year after entering the country (immigration stamp).IDP recognized under the Paris Convention (1926), Washington Convention (1943), Vienna Convention (1968) are not permitted in Japan. *IDP issued in Japan will not be accepted.

On the other hand Avis Australia only requires an IDP if your license is not in a "Roman alphabet":

The Driver must (i) hold a full and valid driving licence (not being a learners licence or provisional licence), (ii) have an International Driving Permit (IDP) or official translation (if licence is not in Roman alphabet), (iii) have held their licence for minimum 12 consecutive months immediately prior to signing the Rental Agreement.

Avis UAE has a list of countries for which an IDP is not required:

All non-UAE residents wishing to rent, are required to hold a valid
International Driving License along with their National Driving
License, except drivers holding driver’s license from the following
countries: GCC countries – Kingdom of Saudi Arabia, Qatar, Oman,
Bahrain, Kuwait European Countries – Germany, Italy, Switzerland,
Poland, Slovakia, Finland, Spain, Netherlands, Greece, Sweden,
Belgium, Ireland, Turkey, Denmark, Portugal, Austria, France, United
Kingdom, Norway, Romania, Luxemburg, Latvia, Serbia, Lithuania North
American Countries – United States of America, Canada East Asian
Countries – Japan, Australia, Singapore, People’s Republic of China,
South Korea, New Zealand, Hong Kong Africa States – South Africa Note
that the original license should be from the same country as the
passport issuing country.

So the answer is yes, its sometimes required. You have to check if your particular license/destination combo is valid by looking up the rental car T&Cs before traveling.

For my first adventure outside Europe, a trip that covered 18 countries (Asia and Australia), I got not just one but two IDPs. My research told me that there were two conventions and that not all of the countries that I hoped to visit had signed the same one. These got very little use, partly because I did not drive much except in Australia and also because on the few times that I did, no one cared.

That was a very long time ago (early 1980s). I have had not had an IDP since. I have driven in the US, Canada, and quite a few Asian countries since and no one has every asked for one.

As other have said, if you are resident then different rules may apply.

In the 1990s, I lived in Sri Lanka and I needed a local licence. I visited a police station, showed my UK licence, and an officer typed my details onto a pre-printed card. Later again, I lived in the Philippines and again got a local licence. This was a bit more complex; I had to take the theory test but not the practical test. I received a credit card sized photo licence similar to my UK one. The procedure took several hours but did not cost much. Renewal can be slow. Once I needed to give a urine sample and take an eye test. The eye test was not hard; the optician asked: “Do you wear glasses?”, I said: “No”, she said: “Are you sure?”, I said: “Yes” and the test was complete.

There may be other things to watch. Here in the UK when we switched to credit card sized photo licences, we were issued paper counterpart licences. In principle, you needed this when renting or driving abroad. I have been asked for a couple of times in the UK (renting a van and test driving a car and a motorbike) but never abroad. I remember once on holiday in Florida, I noticed that some of the people ahead of me in the queue for the rental cars had these counterparts. I was a bit nervous as I had forgotten mine. Fortunately, I was not asked for it.

These counterparts are now obsolete; they have been replaced with a web service. You should visit this before renting. I did before my last US visit but, of course, I was not asked about it.

DVLA View Driving Licence

In the GCC – much like EU – a valid license issued by a GCC member state is valid for other GCC member states.

GCC = Kuwait, Saudi Arabia, Bahrain, Qatar, The United Arab Emirates and Oman.

Visitors to the GCC need to carry their home country license, passport and IDP at all times.

Once you are a permanent resident, you need to get a GCC license – holding permanent residency and driving on your foreign license is a crime punishable by fine, arrest and/or deportation.

I have heard friends renting cars without issue with their GCC driver’s licenses (the licenses have both English and Arabic content) in various EU countries, but none of my friends were ever stopped by the police so I don’t know if this is a hard requirement.

For Spain other than the EU, Switzerland, Norway, Iceland or Liechtenstein all other drivers need the IDP.

Beware – Korea requires one. I arrived to collect my Avis rental, and they refused to give me the keys as I didn’t have an IDP. They were adamant that this is a requirement of Korean law, not just of Avis.

They directed me to the Department of Motor Vehicles and said that the DMV could issue an IDP based on my UK licence. So I spent the morning going to DMV – who said that the IDP can only be bought in home country. So the end result was that I couldn’t get my rental and am taking the train. It messed up my travel plans big time!

Since an IDP is mostly just a dictionary on a very specific topic (being able to drive), the answer depends on reciprocity and ego. To find out if you need an IDP, it is best to learn which countries need an IDP in your country.

The ego comes into the equation, when there are hostile feelings in the general public towards the country you are a citizen of. If you are for example a citizen of a former colonial power visiting a former colony, better bring an IDP, otherwise your license is just a proverbial stick to hit the dog. I have seen it many times, where between two EU drivers one got a penalty because he happened to be from the former colonial power, whereas the other from another EU country was perfectly okay. Yet, technically all EU drivers licenses are the same.

For European countries, you’re at least technically supposed to have one. My friends got fined 250 euros each for riding scooters without international licenses in Barcelona. The scooter rental didn’t request the license, but the cops cared.

I’ve always had one to rent a car, but I’ve never had a rental agent request the license. A USA drivers license, passport and credit card has been always been sufficient to rent a car. I’ve rented cars in Japan, Brazil, Argentina, Chile, Portugal, France and Germany. I have never been stopped by the police and I do not know what would happen in this case. Given that the cost of getting a IDP is small (at least in the USA) and in theory it’s required I would recommend you get one, but in practice it seems like they are not really necessary in many places.

Most Asian countries do not accept a foreign driving license as a valid document for driving vehicles, and legally most of them require International Driving Permits. In practice however, a lot of tourists do not bother to get an IDP and instead leave their passport wherever they are hiring a car/motorcycle from.

If you get stopped by the traffic police though – and in Asian countries, stopping anyone looking foreign driving a vehicle is a big business because they know most people break rules – you will be asked to pay a fine on the spot. Official fines should result in you getting a receipt for the transaction; otherwise, you know the payment you make is a bribe. Many tourists bribe their way out of a situation to save themselves from the ‘hassle’ of getting an IDP but it’s worth remembering that encouraging corrupt practices is not the best thing to do as a traveller.

Even if technically you might be allowed to drive without one, awareness may be low among rental owners or local police. I see in Gagravarr’s answer, for instance, on the Australian RACV list that for Indonesia they list ‘recommended’ instead of ‘required’. I don’t know whether this is a specific waiver for Australian driving license holders, but I know friends who got fined for trying to use an EU driving license when stopped by police. An IDP leaves no room for doubt.

It does vary a lot, depending on both the issuing and visited countries.

For visiting Australia for an example, you either need your license to be in English, or have an IDP that translates it. There’s a much narrower list of countries for whom getting an Australian license doesn’t require a test, see here for more details on those things.

As an Australian, RACV maintain a handy list of which countries need an IDP, which one’s it’s merely recommended for, and which ones you can just drive with your Australian license in. For some examples, UK doesn’t require it, USA recommends it, and UAE requires it.

For how to get an IDP as an Australian, see smart traveller.

Also worth noting that they’re more commonly called an International Driving Permit (IDP) in official circles, rather than an International Driving License.