It supposedly has an edge in terms of pulling out oils in particular.

My problem is that, as you said, it's harder to find, and I have a limitation in what I can use to begin with.

I can't say, when I have used a powder vs a liquid in the past that the difference is so significant that I would bother to hunt down a powder that also fits my niche needs. But if you're not limited, I would say it's worth it on average

The comments here are interesting. There's a very important detail you left out, and everyone is just assuming in their responses.

OP, what are you trying to wash? Laundry, dishes (in a dishwasher, or by hand), or something else entirely?

There's a guy on YouTube that covers this. Powders can contain bleach and cleaning agents in the same mix since they are dry. This gives the best of both worlds. With liquids, the two interact and break down the coach resulting in a poorer result. Pods can keep the components separate but why pay the extra? Something like that anyway. Personal experience is that liquids leave a funky buildup over time that you just don't get with powders.

It all depends on the quality of the product you buy. I tested good brands powder and liquid and they're both good. Liquids are easier to refill in the machine. Powders are a bit better in value.

I read the manual for my washer and have followed that. It “prefers” liquid but can take powder. That being said, I have a few items of clothing that explicitly say powdered detergent only (water repellent material). I’ve found overall that the less liquid detergent I put in, the better it cleans stuff.

Every 20 cycles (my machine tells me) or 1 month, throw in a cleaning powder with either the clean cycle or a heavy hot wash. It’ll help keep it fresh. Also keep the door open when you’re not using the washer to air it out, same reason.

I avoid pods due to microplastics.

TechnologyConnections did a study claiming that the big name powders are enshitifying their products to push you to the more expensive pods.

They promote a full strength powder

https://youtu.be/DAX2_mPr9W8?is=nuoOIO-4qsa9wAZh

I just use laundry detergent strips. Much more compact, works fine.

The problem with the question is us, the consumers. When is the last time you sat down to read the instructions in great detail? A cursory look at the recommended temperature maybe and off we go. Meanwhile a labcoat has produced the greatest formula to clean everything at room temperature. If only we used this much water and these many spin cycles. But no one read the back of the container.

Where I am at, people tend to not do a hot cycle or if they need it they go to a launderette. The liquid works okay on clothes in a cold cycle. But bed sheets and towels start smelling if they don't get at least a 40C/100F cycle every once in a while. And I do that one on powder because it was the only one that wasn't designed to be for cold wash only. So to summarize this extremely boring anecdote: it depends where you are, what your machine is like, and probably on local water quality as well. Or: we'll never find a good answer here that satisfies the demands of the scientific method.

I switched years ago to using Nellie’s Laundry Soda and it’s been great for us. Significantly cheaper per load, cleans well, doesn’t overpower you with fragrance, doesn’t gunk up the soap tray in the washer with the slimy residue, and is easily vacuumed up if it spills.

It’s like $90 for an 800-load bucket that weighs 26.5 lbs (12 kg) from Costco. You use 1 Tbsp (15 mL) of powder per normal load, and 2 if it’s a large or really dirty load. I almost always just use 1 and never had an issue.

Our last bucket lasted almost 2.5 years, and we are a larger family with a lot of laundry. Bought our current bucket last November, so should be good until like February 2028. I have a small plastic container on the washer and then refill it from the big bucket once every couple months.

Pair the soda with OxyClean and it works wonders.

Also stopped using fabric softener entirely and found out it’s really not needed. Dryer sheets work well if you need something; no need for liquids.

Finally, I have rediscovered how awesome bleach can be for laundry, and it is also very inexpensive, so definitely recommend looking into that, too.

EDIT: One more thing— always do your wash cycle on at least warm for virtually everything you wash. Regardless of what soap you use, liquid or powder, it’s not as effective in sudsing and such in cold water as it is warmer. I’ve noticed better results using warm for all my colors and then hot for whites, towels, and the like. Cold is only for specific scenarios or garments. In my experience, ink bleeding really isn’t a thing anymore unless you’re making your own tie-dye shirts or something, which was the justification for using cold for colors back in the day.

Powder has the advantage of not going bad. Liquid on the other hand can.

I tried buying a box of borax for some ant control, but accidentally ordered a case. So I toss some in to every load or laundry these days and it’s really helped my results. I swear colors are brighter and the scent is fresher.

You'd be surprised what just sticking stuff on the line for the wind and sun (and rain) to clean can do with certain fabrics, mostly the naturals, and towels. Overnight in some cases, dew helps, I mean I wash them, but not as often. Dyes may fade, but is that worse than falling apart from washing?

I've heard before that powders/solids are generally easier to mix than liquids, because you can just have all the active parts go when water is added.

With liquids (or really water-based solutions), there's already water in there, so you have to design the reactions, so that they only start when a certain water concentration is reached, which is a lot more fickle and limits you in what you can do.

I could imagine that giving powder an advantage, but I also don't have scientific evidence. ¯\_(ツ)_/¯

Liquid is supposed to be concentrated, if you use too much and don't rinse enough you won't really remove smells/bacteria. As others mention, it is best to read manuals and instructions. If you don't use enough your clothes will smell like the worst thing in the wash.

I hardly see powder for sale in any shops where I live, so liquid gets the convenience points.

When I do see powder, I buy it because it is useful for setting the delayed start on my washer. I used to do pods, but they are awful, especially the pods filled with liquid. The water is so hard where I live, maybe that had something to do with it.

It depends on the brands. Some wash better, some leave better scent, some have built in softner, etc. So maybe the product class alone is not enough to judge.