Airtight food storage containers: six sets, plastic and glass, by what they are actually allowed to do

The six-pack is the sensible first set: two 400 ml boxes for snacks and sauces, three 1-litre boxes for lunches and single portions, and one 2.2-litre box for the salad or the leftover curry. The PLUS range differs from plain KLIP IT in the lid — the leak-proof seal is moulded into it, so there is no separate gasket to lose or to harbour smells — and the clips are the same easy-locking kind. Sistema makes the boxes in its own factory in New Zealand and says its products are phthalate- and BPA-free, though it names the material only as plastic.

Care rules, from Sistema: reheat pre-cooked food in the microwave with the lid off and do not use it for cooking; top rack of the dishwasher only, and make sure the boxes are secure so they do not touch the element; freezer yes, oven, hob and grill no. The shapes are modular — they stack in the fridge and nest in the cupboard with their lids on top — and the pack is 25.6 × 15.8 × 17.6 cm. The warranty is one year against material defects.

It is a plastic set with plastic limits: it will not go in the oven, and reheating a full 2.2 litres of stew for too long can damage the box. For the daily round of packed lunch, fridge, microwave and dishwasher, it is what most kitchens actually need.

Nest Lock is designed around the cupboard rather than the fridge. Five containers — 230 ml, 540 ml, 1.1 L, 1.85 L and 3 L — nest inside the largest, and the five lids snap together into one stack, so the whole set stores as a single 24.5 × 16.3 × 20 cm block weighing 1.05 kg. The bases are colour-coded to their lids, which is the end of the lid hunt that every mixed set eventually becomes.

Joseph Joseph describes the lids as airtight and leak-proof; the care rules are the plastic set’s: microwave for reheating only, with the lid removed and laid loosely on top; top rack of the dishwasher for lids and containers; freezer yes; ovens and grills no. The material is not named on the product page — the FAQ says a variety of plastics, all compliant with EU food-contact rules and free of banned phthalates. The guarantee is two years bought direct from Joseph Joseph and one year through retailers, including Amazon.

The 3-litre top box is the biggest single container in this article; the 230 ml one is the smallest. That range in five pieces, in one block, is the argument. The one-year retail guarantee and unnamed polymer are the counter-arguments.

Three identical boxes is a different idea from a graduated set. Each is Sistema’s 2-litre KLIP IT rectangle — 23.5 × 17 cm and only 8 cm tall, 212 g empty by Sistema’s figures — so the three stack like drawers on a shallow fridge shelf and take exactly the same lid. That suits one thing perfectly: batch cooking, where Sunday’s rice, chilli and roast vegetables go into three matching boxes and come out Monday to Wednesday.

The care rules are the KLIP IT range’s: reheat with the lid off, top rack only, freezer yes, oven no; the lid has a flexible seal and two clips, and the range is made in New Zealand with a one-year warranty. The Amazon three-pack carries the code 1723, which has no page of its own on Sistema’s site; the figures here are for the single 2-litre box (1700) it is made of, and Sistema’s 2.2-litre PLUS trio is the closest documented three-pack.

For a mixed lunch-and-leftovers set, look at the six-pack; for three of the same, big and flat, this is the one.

Fourteen containers and fourteen lids, in graduated sizes with teal clips, in one box: this is the set for a first flat, a student kitchen or a meal-prep habit that has outgrown a six-pack. The box itself prints the rules — microwave safe without the lid, dishwasher safe top rack, freezer safe, stackable, made in New Zealand — and they match Sistema’s KLIP IT range pages, which is where our care facts come from.

What Sistema does not do is document this set. There is no 28-piece KLIP IT set on its website; the nearest documented multipack is a six-pack. So the contents — fourteen containers, largest 12.7 litres of total capacity across the set according to the listing — come from the Amazon listing and the box photograph, and we mark them as pending. The material is plastic (the listing says polypropylene), the warranty is Sistema’s standard one year.

Buy it as a quantity decision, not a quality one: the boxes are the same KLIP IT boxes as the trio above, in more sizes than a small kitchen will use at once. Fourteen lids need a drawer.

Cook & Go is the glass set that does the whole cycle. Seven borosilicate dishes — three rectangles of 0.8, 1.7 and 3.3 litres, two squares of 0.8 and 1.9 litres, two rounds of 0.7 and 1.6 litres — go into the oven without their lids, into the freezer, into the microwave with the lid flaps open, and through the dishwasher. The lids are the point: Pyrex calls them hermetic and waterproof, with four locking flaps and a removable seal you can take out to wash, and says the boxes are suitable for transporting liquids. Soup in a bag is what plastic clip boxes promise and glass ones rarely deliver; this one is rated for it.

Pyrex’s temperature figures: −40 °C to +350 °C for the glass, thermal-shock resistance to 240 °C under EN 1183 — freezer at −20 °C to oven at 200 °C. The glass is pressed in France under the Origine France Garantie label, the lids are BPA-free and have a space to write the contents in pencil, and the guarantee is ten years, the longest here by a decade.

The cost is mass. The set ships at over 7 kg; a 3.3-litre glass dish full of lasagne is a two-hand lift, and none of it belongs in a rucksack for lunch. The lids stay out of the oven, and the seal has to be reassembled the right way round after washing. For cooking, freezing, reheating and serving from one dish, it is the set to buy once.

The Cook & Freeze set is the simpler glass: four rectangular dishes — 0.8, 1.5, 2.6 and 4 litres, from 19 × 14 cm to 27 × 22 cm — with press-on plastic lids meant for the fridge and freezer only. Pyrex is direct about the lids: not watertight, not for transporting liquids, not for the oven or microwave. The dishes themselves have the same borosilicate ratings as the Cook & Go — −40 °C to +350 °C, thermal shock to 240 °C, oven and microwave without lid, dishwasher safe, ten-year guarantee, made in France.

That makes it a batch-cooking set rather than a lunch set: cook a 4-litre dish of something on Sunday, lid it, freeze half, take it from freezer to oven on Wednesday. The four sizes nest, and Pyrex’s table gives the third dish as 24 × 19 cm where its text says 25 — a small inconsistency, recorded. The page is also inconsistent on the thermal-shock figure (240 °C in the standard-referenced statement, 250 °C in one paragraph); we use the EN 1183 figure.

If you want glass for the oven and freezer and will never carry it out of the house, this is the lighter, plainer set. If you want to take Tuesday’s soup to work, buy the Cook & Go.