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An opened bottle of wine stops being stock and starts being a countdown. Left unprotected, oxidation takes it past the point you'd pour it for a guest within one to three days — which is exactly why so many restaurants never put their best bottles on the by-the-glass list at all.
Wine by the glass is the best margin on your entire menu. A six-glass bottle sold at €9 a glass brings in €54, against maybe €18 of cost. Sell the same bottle whole and you're looking at €35–€45 — less, and only when a guest happens to want a full bottle in the first place.
The problem isn't the margin, it's the risk. The moment a cork comes out, oxygen starts breaking the wine down: tannins flatten, fruit fades, and after a few days it tastes and smells like little more than vinegar and cardboard. A bottle you don't pour through in time goes down the drain — and that loss never shows up as its own line item, it just quietly disappears into your drinks cost.
That's why so many wine lists stay conservative: three familiar wines by the glass, and the interesting bottles reserved for whole-bottle sales only. Not because guests wouldn't want to try them, but because the risk of a half-finished bottle going off feels bigger than the margin it could earn.
Four technologies solve exactly this problem, each a different way and at a very different price: a vacuum pump for around €15, an inert-gas spray for around €30, a needle system like Coravin from around €170, and a professional nitrogen cabinet from around €4,000. This article prices all four honestly against each other — including where the cheaper options fall short — and hands you a calculator that works out which one, if any, actually pays back at YOUR volume.
Why 'by the glass' is your best margin — and the scariest thing to offer
The arithmetic is simple once you put it side by side. An €18 bottle with six glasses in it costs you €3 a glass. Sell those glasses at €9 and your margin per glass is €6 — €36 across the whole bottle, against €17–€27 of margin if you sell the bottle whole. At a decent turnover rate, by-the-glass is almost always the better business, especially for bottles that would otherwise sit on the list for weeks because nobody orders a full one.
The catch is that margin only exists if you actually pour the bottle through. A six-glass bottle where you sell three and have to tip out three earns less than if you'd never opened it at all. That's the quiet calculation most wine lists make without writing it down — and it's why the interesting, pricier bottles are usually the casualty: the risk outweighs the margin in the owner's head before the bottle ever gets opened.
A preservation system doesn't change that calculation by growing the margin — it changes it by shrinking the risk. The better the system, the more bottles you're willing to open for the glass without a chunk of each one ending up in the sink — and the more of those €36 margins you actually collect instead of throwing half of them away.
The Ultimate Guide Menu Engineering & Drinks: 6 Steps to More Margin From menu structure to drinks margin — everything your menu can earn you, in one guide. Open the guideThe 4 systems, from cheap to professional
All four do the same basic job — keeping oxygen away from the wine still in the bottle. What differs is how well they do it, and what that costs.
1. The vacuum pump — cheap, but only partly effective
A hand pump that draws air out of the bottle and seals it with a rubber stopper that holds the vacuum. Price: around €15 for the pump and a couple of stoppers, sold in any wine shop.
The catch: a vacuum pump never removes all the oxygen, and the wine clinging to the inside of the bottle stays in contact with whatever is left. It doesn't work at all on sparkling wine — you need the carbonation it's designed to remove. Expect two to five extra days of shelf life over doing nothing, not weeks.
2. Inert-gas spray — a cheap step in the right direction
A canister of argon, nitrogen and CO₂ that you spray over the wine's surface after pouring. The gas is heavier than air and settles like a blanket over the wine, blocking fresh oxygen from reaching it. Price: around €30 for the first canister, refills around €25 good for 80–100 sprays.
Better than a vacuum pump — you're displacing oxygen rather than partly sucking it out — but not perfect: every time you open the bottle again to pour, some of that protective gas escapes and oxygen gets back in. Expect roughly a week to ten days of shelf life under normal use.
Realistic days of good drinking quality after opening, not the absolute best case a manufacturer claims.
These figures are for still wine. Sparkling wine needs its own pressure-holding stopper — none of the four systems above work for it, with the exception of dedicated champagne stoppers.
3. The needle system — pouring without ever opening the bottle
A system like Coravin works fundamentally differently: a thin needle goes straight through the cork, argon pressure pushes wine out through that needle into a glass, and the cork reseals itself the moment you pull the needle back out. The bottle is, in effect, never actually opened — no air gets in, no matter how many times you pour.
Price: entry models run around €170, professional versions with larger capsules go up to €400–€500. Each argon capsule costs around €8 and is good for 15–20 glasses, roughly two to three bottles. That buys weeks to months of pouring the same bottle by the glass — exactly the system restaurants use to put their most expensive bottles on the by-the-glass list without having to sell them off in three days.
4. The nitrogen cabinet — a wine bar in its own right
A refrigerated cabinet with built-in nitrogen dispensing (well-known brands include Enomatic, WineEmotion and Le Verre de Vin) keeps dozens of open bottles fresh at once, often paired with a metered pour system on card or token. Oxygen is displaced almost entirely, so a bottle stays essentially good for as long as it sits in the cabinet.
Price: a small eight-bottle unit starts around €4,000, larger installations with twenty to forty bottles run €15,000–€20,000. Some suppliers rent rather than sell, from around €200 a month. This is the investment that makes it possible to offer fifteen, twenty or more wines by the glass — including bottles that would otherwise be far too risky to open for just one pour.
Of every euro on the table — avoided waste plus glasses you'd otherwise never dare pour — no system captures all of it. This is what each one realistically captures versus what still gets lost.
The gap between 35% and 97% isn't marketing spin — it's the difference between a pump that partly sucks air out and a cabinet that displaces oxygen almost entirely. At low volume it barely matters; on a large by-the-glass list it's the whole difference.
Work out what YOUR system actually pays back
The four systems above are priced at what they genuinely cost. What they're WORTH depends entirely on your own volume: how many bottles you open for the glass each week, how much of each one you currently pour away, and how many extra glasses you'd sell if spoilage weren't a concern.
Type your own numbers below. The calculator recomputes all four payback periods live — and shows you which investment is worth it at your restaurant, and which one isn't.
The payback calculator
Change a number and all four systems recompute instantly.
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The calculator adds two different recoveries together: existing waste the system avoids (net of the system's own running cost) and new revenue from extra glasses you'd otherwise never pour. Both scale with how effective the system genuinely is — a system that solves only 35% of the problem also captures only 35% of both recoveries.
Watch what happens when you raise the bottles-per-week number: the cheap systems keep paying back within days, but the nitrogen cabinet suddenly jumps from 'never' to 'within a few months'. That's the whole lesson — a nitrogen cabinet isn't a better vacuum pump, it's a different investment for a different kind of venue.
And watch what happens when you set 'extra glasses' to zero: a large share of the return disappears for every system. The real value of preservation isn't just less waste — it's the bottles you don't dare pour by the glass NOW, and will later.
Which system fits your venue
A rough rule of thumb, based on how many wines you actually want by the glass:
Two or three house wines by the glass, high turnover
- A vacuum pump or inert-gas spray is enough — those bottles are empty within a few days anyway.
- Put the difference toward a better house wine instead of preservation hardware you barely need.
A rotating list of five to ten wines by the glass
- A needle system is usually where the arithmetic tips: it lets you put pricier, slower-moving bottles by the glass without half of each one going down the drain.
- Expect a payback of a few weeks to a couple of months at an averagely busy list.
A wine bar or fine-dining list with 15+ wines by the glass
- Only here does a nitrogen cabinet realistically pay back — it's the volume and the premium pricing that a list that size carries which justifies it.
- Run your own numbers through the calculator above before committing: at a smaller volume it takes years.
The margin isn't in the bottle — it's in what you actually sell of it
None of these four systems increases your margin on wine — that margin already exists, in every bottle you currently only dare sell whole because a by-the-glass list feels too risky.
What they do is actually let you collect that margin: less wine down the drain, and more of your best bottles finally on the by-the-glass list. Which system does that fastest for you depends entirely on how many bottles you open a week — run your own numbers before you buy.
And start small if you're unsure: an inert-gas spray at €30 costs you almost nothing to try, and tells you within a month whether you're ready for the next step.