Tipping has reached the tipping point for most of us. Everywhere we turn, the unwritten rules are different. Waiters and hotel porters in Japan consider tips to be rude, as it implies they are not paid enough.

In the US, it's become customary in many restaurants and bars to add 25 per cent to bills, whether service was good, bad or indifferent.

Yet respecting the culture is an important part of any trip. So how best to show your gratitude?

With help from the travel experts at consumer champion Which?, here's what you need to know.

Understanding the basics

Confusion reigns over the difference between 'service charge' and 'gratuity', but the terms can be used interchangeably and refer to an additional payment on the bill. A tip is any payment you choose to make in addition to the bill.

Unlike in Ireland, the service charge in the rest of Europe is usually included. You can expect to find it in restaurants in France ('service compris'), Italy ('servizio' or 'coperto'), as well as Greece and Portugal. A 10 per cent service charge is increasingly the norm in Australia, too.

The bottom line

There are no hard and fast rules, but at most European restaurants an additional 5 to 10 per cent, on top of the service charge, is considered generous. In countries such as the US, where tipping is firmly engrained, 20 per cent has become standard - rising as high as 25 per cent in places such as New York City and California. So between 5 and 25 per cent is the tip 'wiggle room'.

In France or Italy, no matter how grumpy or slow your waiter, service charge is mandatory and can't be refused. But it's illegal to add a compulsory charge in Spain, and you can request its removal should you see fit. There's no legal obligation to tip in the US, but not doing so is generally considered a social faux pas.

Cash versus card CASH is usually preferred. If you pay by card, it may not get to staff.

Tip before tax is added

Wherever you are in the world, calculate tips as a percentage of your bill's total before tax is added.

For holidays free of fretting over tipping etiquette, go all-inclusive. Gratuities are usually included in these packages. But for staff who have gone above and beyond, an extra tip is always appreciated.

Rules for the high seas

Operators such as Saga and APT River Cruises are all-inclusive. Otherwise, around €15 per day, per passenger for ship staff and your programme director is recommended. If that doesn't float your boat, look out for cruise lines such as Oceania, which automatically adds €15pp/pd to your bill.

Tour guide tipping

Again, there are no set rules here - the expected tip varies between countries. However, a 10 to 20 per cent tip is common in most countries, with contributions on the higher end of that scale expected for private tours.

'Free' walking tours

Popular in lots of cities, free walking tours are usually given by locals and have a 'pay what you want' approach to tipping. You're not required to pay anything, but it's polite to give a €5-10 donation (in local currency) to the guides.

At the bar THE French word for gratuity is 'pourboire' - literally 'drinking money'. But don't be fooled - it's not customary to tip in bars in France. In the US, Canada and Mexico, a tip of $1-2 dollars per drink is usually expected. Tipping in bars is also becoming common in Asian countries such as Thailand and Vietnam.

Hotel porter etiquette

It's customary to tip porters in high-end hotels - $5 a bag in the US is considered normal, or €5 for two bags in Europe.

Chambermaids

Housekeeping staff should be tipped - with daily cash contributions preferred to a lump sum at the end of your stay (as staff rotate shift patterns). Leave tips in a visible location.

'Baksheesh' basics

A tip or charitable donation associated with Egypt, it's also present in other parts of North Africa, the Middle East and Asia. Expect to pay around 10-20 per cent of a restaurant bill. Dollars in cash are usually welcome.

Best tip-free spots

The etiquette in Japan is fairly explicit: if in doubt, leave it out. The same goes in China, though tips are acceptable in touristy areas. Denmark is tip-free, but it's considered polite to round up restaurant and bar bills.

Do your research

Be aware of cultural quirks. In Poland, saying 'thank you' before getting your change implies staff can keep it. Wherever you go, carry change in local currency and be discreet when giving it.