Festive shrinkflation: tricks chocolate makers use to make us pay more | Consumer affairs

The unit prices are marked up on the shelves but from the outside it is not obvious that you are buying a box with a small bag inside. The box effectively costs £1.52 once the price difference and the 10% fewer sweets are taken into account.

Pricing quirks and the cost of excess packaging are always worth bearing in mind, particularly around Christmas and Easter when manufacturers invent new ways to present their goods.

This year, Mars’s Celebrations brand is available in a new “centrepiece” box, which holds 385g of the sweets. It typically sells for £1 more than a pouch weighing 370g, and at the same price – or more – as a plastic tub weighing 650g. In Tesco, for example, the pouch is priced at £3.50, or £2.50 for Clubcard holders, the centrepiece box at £5, or £4 for Clubcard holders, and the plastic tub at £4. Respectively, that’s a cost per 100g of 95p (or 67.5p with a Clubcard), £1.30 (or £1) and 62p.

It is a discrepancy that’s not gone unnoticed by online shoppers. On Ocado’s website the centrepiece box gets one star, although at the time of writing it had been reduced from £5 to £3.50. The most recent purchaser, who posted on Tuesday, complained that they had “paid the price of a big box for a tiny one”.

Ele Clark, a retail editor at the consumer group Which?, says: “While prices will inevitably differ between supermarkets, shoppers might be less aware that the price per 100g of a branded product can also vary enormously within a store, depending not only on the pack size but also the packaging type.

“Some options will offer much worse value for money than others, so pay attention to the prices per 100g – and don’t assume you’re getting a good deal just because the item is on offer.”

Helen Bird from the waste reduction charity Wrap says that while presentation “can be an important part of the gift experience”, it often means more packaging.

If you are trying to choose between different packs based on their environmental impact, she says: “A general rule of thumb is the longer we use things, the better it is for the environment. Some packaging is designed to be repurposed, such as fancy tins. But another general rule is that the heavier the packaging, the more resources it is using and the more fuel it will consume in transportation. So if we’re not going to reuse something, a lighter pack may be better.”

Mars Wrigley, which makes Celebrations, has this year reduced the plastic in its pouches by 19%. It says pricing of its products is at a retailer’s discretion.

A spokesperson says: “At Mars Wrigley, our focus is always on ensuring we offer our great-tasting, high-quality chocolate at the best possible value. We have a range of Celebrations treats on sale this Christmas that, while available in different sizes, formats and price points to suit all occasions, provide value for money to the British public this festive season.”

Bird says that once the packaging is finished with, it is important to recycle as much as possible.

“Most packaging can now be recycled at home but paper or card that has glitter on it should not be recycled, so it’s also best to avoid buying it, too. Plastic bags, wrapping and pouches are generally not recyclable at home but several supermarkets, including Tesco, Sainsbury’s and the Co-op, provide recycling collection points at their stores as part of their efforts to hit UK plastics pact targets for all plastic packaging to be recyclable by 2025. You can find out what and where to recycle at www.recyclenow.com.”