TL;DR
Fill a washer drum about three quarters full and leave roughly a hand width of space at the top. Clothes clean by moving through detergent solution, so a packed drum cannot clean, cannot rinse, and cannot spin properly. Underloading wastes water and lets items ball up, so the target is a comfortably full drum, not a crammed one or an empty one.
How full should a washing machine be?
Load a front loader to about three quarters of the drum, loosely, with room to press your hand flat on top of the pile. A top loader with an agitator should fill to the top row of holes without packing around the post. In both cases, clothes should be able to tumble or circulate freely once water is added.
Why a packed drum stops cleaning
Washing works by mechanical action. Fabric has to move through detergent solution so the surfactants and enzymes reach the soil, lift it, and carry it away. When the drum is full, the pile moves as one block instead of as individual garments.
Three things go wrong at once.
Soil does not release. The middle of the pile barely sees fresh solution. Items come out looking washed but still carrying body oils and odor, which is why smells sometimes survive a wash.
Rinsing fails. Detergent goes in, but it cannot fully come back out. Residue stays in the fibers and builds over successive loads, which shows up as stiff, dull fabric and towels that stopped absorbing. If your laundry already feels that way, signs of detergent buildup on clothes covers how to undo it.
Spin goes off balance. A heavy wet mass on one side of the drum makes the machine shake, walk, or stop mid-cycle. Over years, that stress wears bearings and suspension components. It is one of the more expensive habits in a laundry room.
The wet weight problem
Dry laundry is deceptive. Cotton absorbs a great deal of water, and a load that looks reasonable dry can weigh several times as much once soaked. Towels and bedding are the worst offenders, which is why a bath towel load that fit fine going in can slam the drum around during spin.
This is also why the manufacturer capacity number is not a target. Capacity is stated as a dry weight for a specific load type under test conditions, not a promise that any pile filling that volume will wash well.
Source: Association of Home Appliance Manufacturers
How to check load size without a scale
A few quick physical checks work better than guessing.
The palm test. After loading a front loader, lay your hand flat on top of the clothes. If your palm fits between the pile and the top of the drum, you are close to right. If it does not fit, remove something.
The fist test for top loaders with an agitator. Load loosely around the post, not wrapped around it, up to the top row of holes. You should be able to push a fist down into the clothes easily.
The tumble check. Start the cycle and watch for thirty seconds through the door or lid. Clothes should visibly move and change position. If the pile rotates as a solid mass, it is too full.
The after-wash check. Open the door at the end. Clothes should be loose and separable. If they come out as one twisted rope, the load was too big, the spin was too fast, or both.
Underloading is a real problem too
Running three shirts in a large drum is not gentle -- it is inefficient and sometimes harder on the clothes. Small loads tangle, wrap around each other, and take the full brunt of the agitation with nothing to cushion them. They also use far more water and energy per item.
Most machines have a load size or auto-sense setting that adjusts water volume. Use it. If your machine senses load weight automatically, adding items after it has already measured the load will throw the calculation off, so load first, then start.
Bulky items follow different rules
A comforter, a sleeping bag, a mattress pad, or a set of heavy curtains should go in alone. These items absorb enormous amounts of water and need room to move, and they will trap other garments inside their folds if you add them.
Use the bulky or bedding cycle where available, and stop the machine partway through to redistribute if it sounds like it is fighting. If a comforter fills more than about three quarters of your drum while dry, it is too big for the machine and belongs at a laundromat with a larger capacity unit. Forcing it in risks both a poor clean and a damaged machine. Picking the right washer cycle covers which setting handles bulk properly.
Load size and drying are connected
An overloaded washer produces poorly spun clothes, and poorly spun clothes take much longer to dry. Then those wet clothes typically go into an overloaded dryer, where the same problem repeats -- air cannot move through the pile, so moisture cannot leave. That is the usual cause behind why clothes take two cycles to dry.
Splitting a giant load into two properly sized loads often finishes faster overall, because both the wash and the dry actually complete the first time.
FAQ
Can you overload a front load washer?
Yes, and front loaders are less forgiving than top loaders about it. They use less water and rely almost entirely on clothes falling through a small pool of solution, so a packed drum eliminates the tumbling action that does the cleaning. Leave a hand width of space at the top.
Does a bigger load use less water per item?
Up to the correct fill level, yes -- a properly full load is the most efficient way to run a machine. Past that point, efficiency reverses, because you end up rewashing items that did not come clean the first time.
Why does my washer shake and move during spin?
Almost always an unbalanced load. Heavy wet items settled on one side of the drum. Stop the cycle, redistribute the clothes evenly, and restart the spin. If it happens on properly sized loads too, check that the machine is level and that shipping bolts were removed at installation.
Should towels and sheets be washed together?
It is better to keep them apart. Sheets wrap around towels and trap them, so neither gets clean and the load goes off balance. Wash sheets as one load and towels as another when you have enough of each, and see how to sort a load of laundry for the rest of the sorting logic.
How full should a top load washer with an impeller be?
Impeller machines have no center post, so load evenly in a flat layer around the bottom rather than a mound in the middle, and fill to about three quarters of the drum. Do not wrap large items around the impeller plate.
Will running smaller loads make clothes last longer?
Slightly, if you also use a gentler cycle. But very small loads tangle and take the full force of agitation, so the gain is modest. Correct sizing and correct cycle choice matter more than load count.
This sits inside the broader whole-home work covered by house cleaning services.
Load size is the cheapest laundry fix there is, and it changes results the same day. If the laundry pile is a symptom of a house that has generally gotten ahead of you, that is a normal thing to hand off. Every home is different, so the real number depends on size, condition, and what you want covered. Get a quote and we will walk you through it.