The image of wannabe hip-hop moguls drinking oversized bottles of Cristal in club corners has done nothing for the reputation of the magnum. But when it comes to wine, bigger often means better. There is something about a magnum, or “large formats” as they are called in the wine trade, that screams “celebration”. There is a certain theatre to ordering and pouring them, and the sight of a gargantuan bottle of wine is always going to make the centrepiece of the dinner table a real magnum opus.

The fact that restaurants and wine merchants are stocking increasing amounts of their wine in magnum size – Mr Jason Atherton’s Social Wine & Tapas in London recently doubled its magnum list, for example – shows there’s more to it than pure show. They last longer, of course, but a magnum, which clocks in at 1.5 litres, twice the size of a standard bottle, is seen as the optimum for ageing wine. And if you’re savvy, larger formats can return a tidy profit.

We spoke to five wine experts to find out exactly why we should be delving a bit deeper into the wine list this holiday season.

If you’re throwing a dinner party, it’s all about setting the correct tone. And, according to two-Michelin-star chef Mr Michel Roux Jr, there is no better way of doing that than with a magnum. “There’s a spirit of generosity and conviviality as soon as you see a magnum on the table,” he says. “When we’re having a family celebration, there will always be a couple on the table – they look impressive.”

If you’re attending a party where you need to bring a bottle, turning up with something opulent in size shows you mean business. Mr Alex Whyte, co-founder of world-renowned Italian wine importer Tutto Wines, recommends selecting something from a grower that produces only its top cuvées in magnum. “Roberto Voerzio’s Barbera d’Alba Riserva Vigneto Pozzo dell’Annunziata from Piedmont, Italy, is extra special and it gives another level of oomph by going all out in terms of presentation with a unique embedded label and hand-blown glassware,” he says.

Do the maths. If you’re going out to dinner with a large group, ordering a bigger bottle makes sense. “Pouring wines by the glass from a big bottle, be it a magnum, a jeroboam, or nebuchadnezzar [see our sizing guide below], makes a whole lot of sense for groups of any size,” says Mr Whyte. “Why switch wines every five minutes or risk having two bottles of the same wine that are different when you can all sit around enjoying it, rather than delving into the list every few minutes?” It’s worth remembering that the standard 75cl bottle is rather outdated – it was deemed “the appropriate amount a man should drink over dinner” in 18th-century Napoleonic France. Our tastes, and perhaps our capacities, have evolved.

Mr Richard Rotti, wine buyer for The Ivy in London, agrees with this logic. He likes to serve red wine, such as an old-fashioned Barbaresco from Olek Bondonio or proper Aglianico from Cantina Giardino, in magnums. “I tend to look for these in large format because if you have waited 10, 20 years for a wine to come good and it turns out to be amazing, a bottle is never going to be enough. The whites I go for are a Vitovska from Marko Fon in Kras – a tiny, remote village in Slovenia – or a Chenin Blanc from the Loire that has spent a long time resting in the barrel, such as Jean-Pierre Robinot or Olivier Lemasson.”

If a producer is making wine in magnum size, you know you’re guaranteed their A game, as it will represent the wines and vintages they want to show off. But better value doesn’t necessarily mean cheaper. The materials, such as the bottle, label and cork, are bespoke, so “magnums command a shorter bottling run and you’ll pay around an eight per cent premium,” says Mr Rotti, who also selects wine for Sexy Fish, a pan-Asian restaurant in Mayfair, London. With the bespoke elements, however, you will benefit from extra care and attention and, according to Mr Max Lalondrelle, the fine wine buying director at Berry Bros & Rudd (wine merchant to the Queen, no less), there is value to be had. “Bordeaux wines, especially young vintages, can be cheaper in magnums than in bottles,” he says. “It’s due to Asian markets snapping up young Bordeaux in standard bottles, as they have yet to get into buying magnums.”

On the whole, Mr Lalondrelle suggests investing in the old world. “I would recommend buying magnum wines from good estates in Bordeaux, Burgundy or Champagne at the medium end of the market because they outlast bottles of a better quality wine and still remain affordable,” he says.

There’s science behind the thought that drinking from large formats produces a better taste. “As there’s more wine in the bottle and less ullage [empty space between wine and cork], it means a proportionately smaller amount of air in the bottle – which is what causes ageing (through oxidation),” says Mr Rotti. “There is therefore a prolonged maturation, and the wine will often develop greater nuances and more complex flavours than wine aged in standard bottles.” Mr Michel Roux Jr, owner of London’s Le Gavroche agrees. “They’re the ideal size for ageing and maturing the wine.” Champagne also benefits from being in magnum size. To cut the science short, autolysis – the gradual breakdown of yeast cells that gives Champagne its effervescence – works better in a magnum because of the greater glass surface area, which allows more contact between the yeast cells on the inside of the bottle and the wine, thus creating more fizz. And if you can resist drinking a bottle, it can become a little investment. “You can buy your favourite non-vintage fizz, lay it down for three years and have the equivalent of vintage wine for half the price,” says Mr François Domi from Champagne Billecart-Salmon, a champagne house founded in 1818.

Don’t be tempted to go any bigger, however. “The magnum allows Champagne to maintain the tension between acidity, sugar, fruit and fizz,” says Mr Rotti. “Champagne is always sexier in big bottles. But don’t go above magnum. Double magnums and bigger involve the wine being decanted into these huge bottles, risking corking.” Remember to age wine at around 12 to 17°C, laying it on its side, in 60 per cent to 90 per cent humidity, with low lighting and vibrations to keep the cork’s integrity.

Air that enters a bottle after it has been opened causes the flavour of a wine to deteriorate. With the advent of gadgets such as the Coravin and Enomatic, which suck air from the bottle, sommeliers can give restaurant guests the opportunity to try a glass from a magnum without the fear it will spoil. If a restaurant is advertising glasses from a magnum, you’ll know it is serious about wine. “It allows us to show off the most special wines on our list and put them table-side, straight from the bottle. We can then speak to the guest about the nuances of flavour from oversized bottles so they can learn at a fraction of the cost,” says Mr Rotti.

Restaurants are continually updating their wine lists to adapt to the changing tastes of customers. For example, Clos Maggiore, a French restaurant in London, has started offering 72 of its wines in magnums. And the choice is only increasing. Ms Laure Patry, head sommelier at Mr Jason Atherton’s forward-thinking, wine-focused Social Wine & Tapas, agrees that larger formats are an important part of the dining experience. She offers a generous selection of excellent value magnums. “We have a Christian Tschida Syrah Felsen II from 2011 that drinks fantastically at £315, and a Benoit Courault Tabeneaux from 2010 at just £92.”

Double-sized bottles not enough? If you really want to celebrate in style, you need to know your imperial from your balthazar, though bear in mind the names can vary depending whether the bottle is a Champagne, Bordeaux or Burgundy.

Standard (750ml): The common bottle size for most distributed wine – six glasses.

Magnum (1.5 litres): Equivalent to two standard bottles – 12 glasses.

Double magnum (3 litres): Two magnums or four standard bottles – 24 glasses.

Jeroboam (4.5 litres): Six standard bottles – 36 glasses.

Imperial (6 litres): Eight standard bottles or two double magnums – 48 glasses.

Salmanazar (9 litres): 12 standard bottles or a full case of wine – 72 glasses.

Balthazar (12 litres): 16 standard bottles or two imperials – 96 glasses.

Nebuchadnezzar (15 litres): 20 standard bottles – 120 glasses.