What You Should Not Put in a Blender

There is exactly one item on this list that can injure you, and it is not the one most articles lead with: hot liquid in a sealed vessel. Everything else here costs you a blade, a jar, a motor or a disappointing breakfast. We have sorted the list that way, because a page that files “boiling soup in a bullet cup” next to “dried fruit” is not helping anyone decide what to be careful about.

Dangerous: hot liquid in a sealed vessel

Hot liquid releases steam. In a closed container, steam has nowhere to go, so pressure builds — and the moment the seal gives or you unscrew the lid, the contents come out fast and they are hot. The worst version is a bullet-style cup, where a blade base is screwed on tight and the whole vessel is designed to be airtight. The NutriBullet Pro (900 W) is a sealed-cup machine and this prohibition applies to it directly.

This is the one entry worth reading a whole page about, and we wrote two: the general case on blending hot liquids safely, and the single-serve case on can personal blenders handle hot liquids. The short version: never fill past a third, never seal it, vent the lid, and if you blend hot food often, use a stick blender in the pan instead — the Braun MultiQuick 7 MQ7035X scores highest in our catalogue on hot liquids for exactly this reason.

Damaging: four things that cost you hardware

Bones, pits and stones

Peach and cherry pits, olive stones, chicken bones. Harder than the blade and harder than the jar, so something has to give and it will not be the pit. This is the clearest case of “do not” on the list after hot liquid, and unlike hot liquid the consequence is a repair bill rather than a burn.

A full jar of anything frozen, with no liquid, on a low-amperage machine

Not inherently damaging — damaging when you hold the switch down against a load that is not moving. The motor is working at full draw and doing no work, which is how heat builds. The Hamilton Beach Power Elite Wave Actionpublishes a 3.7 A rating plate in its own manual and its skip line says outright that a dry frozen jar will stall it. The fix is liquid, not persistence: do you have to thaw frozen fruit before blending.

Dry grain, spice and coffee in a wet jar

Not a motor problem — a jar problem. Hard dry particles at blade speed are abrasive, and the haze they leave in a plastic container does not polish out. It is one of the few genuine arguments for glass. Dry work belongs in a container built for it, and which maker publishes one is on best blenders for grinding grains and spices.

Anything above the maximum fill line

The line is there because a blender needs headroom to circulate and because liquid climbs when it spins. Over it, you get a leak past the lid at best and no circulation at all at worst. The Ninja Professional Plus BN701is a useful example of the distinction: SharkNinja publishes 72 oz total and 64 oz maximum liquid as two separate numbers, which is the honest way to state it, since the brim is not the capacity.

Pointless: six things that just give a bad result

• Potatoes, if you want fluffy mash. The blade ruptures the starch granules and you get paste. It is a texture failure rather than a hardware one, and it is almost impossible to undo. The least-bad powered approach is on best blenders for mashed potatoes.
• Coffee beans, if you pull espresso.A blender chops rather than mills, so the output is a mixture of dust and chunks that cannot be dialled in. Fine for cold brew, useless for espresso — can you grind coffee in a blender goes brew method by brew method.
• Dough and thick batter. A blender has no low-speed torque and no hook; it will climb the walls, stall, and load the motor while doing nothing. This is a stand mixer or a food processor job, and the division of labour is on blender vs food processor.
• Dried fruit on its own. Dates, raisins and apricots are sticky rather than hard: they ball up around the blade and stop moving. Soak them first, or add them to a mixture that already has liquid in it.
• Whole fibrous stalks.Celery strings, kale ribs and the woody end of ginger survive blending as recognisable threads, which is where most “why is my smoothie gritty” complaints come from. Chop them, or leave them out.
• Anything you want to keep whole. A blender has one setting conceptually: smaller. If you want chopped rather than pureed, that is a food processor, and a pitcher blender will overshoot every time. The ranking for machines that genuinely do both is on blender and food processor combos.

Things on other people’s lists that we think are fine

Ice. Routinely listed as forbidden and routinely sold as a feature. Every full-size machine we rank is marketed as handling it; what varies is how well, and the ranking is best blenders for crushing ice.

Frozen fruit. Softer than ice. Fine on anything with real power, and the whole point of a smoothie.

Nuts.Fine, and nut butter is one of the jobs premium machines exist for — with a tamper. Without one it is tedious rather than forbidden.

Hot soup in an open, vented, properly-filled pitcher.Fine, and some machines are sold on it. The hazard is the seal and the fill level, not the temperature in itself — which is why we separated the dangerous version out at the top of this page rather than banning the whole category.

What we are not going to tell you

We have not broken a blender to find out where the line is, and we publish no torque figure, no maximum particle hardness and no temperature limit, because no manufacturer publishes them. Everything above is either a published limit read off a maker’s own document — a rating plate, a maximum liquid figure, a stated prohibition — or reasoning about how a blade interacts with a given load, stated as reasoning. Your own machine’s use-and-care document outranks this page every time. Our method is published in full.