Washer to Dryer Throughput Balance Calculator

Washing and drying are two stages of one line, and a line runs at the pace of its slower stage no matter how good the other one is. Everyone knows this and almost nobody has the two numbers written down in the same units. Put both stages into pounds an hour and the argument settles itself: one of them is the constraint, the other is idle for a measurable fraction of the shift, and if the washers are the fast end then wet linen is accumulating in carts at a rate you can count. This does that arithmetic and then shows what a shorter dry time does to it.

From the machine data plate. If your washers differ, run this once per group or use a weighted average pocket.
Weigh what goes in for a shift and divide by the rated pocket. In a self-serve store this number is set by customers and is usually lower than anyone expects.
Unloading and reloading, plus the wait if nobody is standing there. In a self-serve store this is often larger than in a plant and it is pure lost capacity.
Count pockets, not cabinets. A stacked pair is two.
Rated on the dry weight of the goods, same basis as the washer. A dryer pocket rated at the same pounds as a washer holds it far more loosely, which is the point of the larger drum.
Underloading a dryer wastes the pocket; overloading it lengthens the cycle more than it adds pounds. Measure rather than assume.
Time a real load from start to the moment somebody could take it out. If you want to work this from the moisture the extract leaves behind, the dryer energy calculator does that.
Optional. Used to weigh the wet carts and to rescale the dry cycle if you change the extract below.
Optional. A different extract, a different machine, a press. The dry cycle is rescaled by the ratio of water removed, which assumes a flat evaporation rate.
Wet weight, not dry. A cart that takes 80 lb of wet goods takes far less than 80 lb of dry ones.
Washer to Dryer Balance Calculator — Which Stage BindsBuildFigure

Put both stages in pounds an hour

Nearly every argument about laundry capacity is two people quoting numbers in different units. Washers get talked about in machines and cycle times, dryers in pockets and minutes, and neither converts in anyone's head. Pounds an hour settles it. A washer stage is machines times pocket times fill times sixty over the door-to-door minutes; a dryer stage is exactly the same shape. Once both are in the same units one of them is obviously smaller, and that one is the line rate.

Door to door matters more than the cycle timer. A 28 minute wash that sits six minutes before anyone empties it is a 34 minute machine, and in a self-serve room that gap is set by customers rather than by staff. It is routinely the largest single piece of lost capacity in the building and it costs nothing to measure — a stopwatch and an afternoon.

The pile between the stages

If the washers are faster, running them flat out does not produce a single extra pound of finished laundry. It produces wet linen in carts. That is worse than an idle washer, because the carts and the floor space are real, and because wet goods parked warm become a different kind of problem the longer they sit. The page counts the pile in dry pounds, converts it to what it actually weighs at your retention, and turns it into carts.

The disciplined answer when the dryers bind is to run the washers at the dryer rate and take the difference as a shorter shift, not as a stack. The expansion answer is the pocket count the page prints, which is the number of dryer pockets that would consume everything the washers can produce.

Improvements stop paying without warning

Two-stage lines behave in a way that catches people out: an improvement to the slow stage helps right up until that stage stops being the slow one, and then it helps not at all. The optional extract block shows this directly. Cut the moisture the washers leave behind, the dry cycle shortens in proportion to the water removed, the dryer stage speeds up — and at some point the washers become the constraint and every further point of extraction buys nothing on this line.

That is not a reason to stop improving the extract, because the fuel saving continues even after the throughput gain stops. It is a reason to know which of the two you are buying before you spend anything.

Why the pockets-per-washer ratio is computed and not quoted

Ratios get passed around as bare numbers and they are close to meaningless on their own. A balanced ratio depends on both pocket sizes, both fills and both door-to-door times, and every one of those differs between stores. A plant with a press and a short dry cycle needs fewer pockets per washer than a self-serve room where everything comes out of a soft-mount washer at high retention. The page works the ratio for the machines you described, which is the only version of the number that means anything.

Questions people ask

How many dryer pockets per washer do I need?

It follows from both cycle times, both pocket sizes and both fill percentages, so the page computes it rather than quoting a rule. A store with a hard extract and a short dry cycle needs fewer pockets than one running high retention out of the washers. Enter your machines and the balanced ratio comes out at the bottom, along with the pocket count that would consume everything the washers can produce.

Which is the bottleneck, the washers or the dryers?

Whichever does fewer pounds an hour once turnaround is counted. The page puts both stages in the same units and names the slower one, then shows what fraction of the time the faster one is standing still. If the two come out close, the answer will flip with the fill percentages, so measure those before acting on it.

What happens if I run the washers flat out when the dryers are the constraint?

You produce wet linen, not clean laundry. Output is capped by the dryers regardless, and the surplus accumulates in carts at a rate the page counts for you. The carts, the floor space and the handling are real costs, and wet goods sitting warm do not improve. Running the washers at the dryer rate and taking the difference as a shorter shift is the same output for less trouble.

Does a better extract increase throughput?

It shortens the dry cycle in proportion to the water removed, so it increases throughput while the dryers are the binding stage and stops doing so the moment the washers become the constraint. The optional block on the page shows exactly where that crossover falls for your machines. The fuel saving carries on either way, which is a separate benefit worked out on the dryer energy calculator.

Should turnaround time really be counted in the cycle?

Yes, if you want a number that matches reality. A machine that is standing full and waiting is not available, and capacity that cannot be reached is not capacity. Counting it separately is how stores convince themselves they have headroom they have never once achieved. Time it door to door on a normal day rather than on a day somebody is watching.

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