Hoshizaki KM Water Filter Sizing: Every Model, With the Arithmetic Shown
If you run a Hoshizaki KM cuber and want to know which filter it needs and how long the cartridge will actually last, this page has the numbers — read off Hoshizaki's own specification sheets and Everpure's, with the division done for you.
There is one finding worth putting at the top, because it surprised us and it will probably surprise you:
At rated production, every Hoshizaki KM model in this range exhausts an Everpure Insurice Single before six months. Not one of them makes the standard interval on the smallest system.
First, the sizing method everyone gets wrong — including us
We used to tell readers to size an ice machine filter on peak flow during a fill cycle, and to find that figure on the machine's spec sheet.
We went looking for it on Hoshizaki's sheets in order to write this page. It is not there. There is no gpm figure, no flow rate, no instantaneous draw anywhere on the KM-515M_J or the KM-350/520/660M_J sheets. What Hoshizaki publishes is ice production in pounds per 24 hours at two ambient conditions, potable water use in gallons per 100 lb of ice, condenser water use, and a supply pressure range of 10–113 PSIG.
So we corrected our own guides, and here is the method that actually works — the one the filter manufacturers use themselves. 3M's ice machine filter sizing sheet says it plainly:
"Find the right filter to fit your commercial ice equipment needs based on the amount of ice it produces per day."
Both of 3M's sizing tables carry the heading "(sizing for 6-month cartridge change)".
The cartridge's flow rating is still a genuine ceiling — Everpure states "Service flow rate must not exceed 1.67 gpm" — but you have no published machine figure to check it against, and the filter manufacturers have done that conversion for you. Pounds per day is the number you can actually act on.
The Hoshizaki KM numbers, as published
Straight from the two specification sheets. Production is quoted at both of Hoshizaki's stated test conditions, because the difference between them is large enough to change your answer.
| Model | Condenser | lb/24h at 70/50°F | lb/24h at 90/70°F | Potable gal per 100 lb | Condenser gal per 100 lb |
|---|---|---|---|---|---|
| KM-350MAJ | Air | 489 | 393 | 14.5 | — |
| KM-350MWJ | Water | 414 | 383 | 15.5 | 109 |
| KM-515MAJ | Air | 517 | 450 | 16.0 | — |
| KM-515MWJ | Water | 495 | 457 | 15.6 | 80 |
| KM-515MRJ | Remote | 504 | 454 | 20.5 | — |
| KM-520MAJ | Air | 556 | 480 | 14.7 | — |
| KM-520MWJ | Water | 474 | 444 | 14.8 | 75 |
| KM-520MRJ | Remote | 547 | 495 | 13.6 | — |
| KM-660MAJ | Air | 650 | 560 | 14.8 | — |
| KM-660MWJ | Water | 669 | 668 | 16.1 | 152 |
| KM-660MRJ | Remote | 642 | 570 | 15.0 | — |
The KM-301BAJ is deliberately not in this table. Its specification sheet covers a single model, which removed a cross-check we relied on for the others, and two figures on it could not be confidently assigned. We would rather leave it out than guess.
The arithmetic, done
Cartridge life is one division: rated capacity ÷ gallons used per day.
Gallons per day is production × potable gallons per 100 lb ÷ 100. Everpure's Insurice Single-i2000² is rated at 9,000 gallons and the Twin-i2000² at 18,000.
Every figure in this table is at rated 90/70°F production, which is the pessimistic case and the right one for sizing. Read the duty-cycle note underneath before you act on it.
| Model | Gal/day at rated | Single (9,000 gal) | Twin (18,000 gal) | What you need for six months |
|---|---|---|---|---|
| KM-350MAJ | 57.0 | 158 days | 316 days | Twin |
| KM-350MWJ | 59.4 | 152 days | 303 days | Twin |
| KM-515MAJ | 72.0 | 125 days | 250 days | Twin |
| KM-515MWJ | 71.3 | 126 days | 252 days | Twin |
| KM-515MRJ | 93.1 | 97 days | 193 days | Twin |
| KM-520MAJ | 70.6 | 128 days | 255 days | Twin |
| KM-520MWJ | 65.7 | 137 days | 274 days | Twin |
| KM-520MRJ | 67.3 | 134 days | 267 days | Twin |
| KM-660MAJ | 82.9 | 109 days | 217 days | Twin |
| KM-660MRJ | 85.5 | 105 days | 211 days | Twin |
| KM-660MWJ | 107.5 | 84 days | 167 days | Twin is marginal — step up |
Six months is 180 days. Read down the Single column: the best case in the whole range is 158 days and the worst is 84. A Single-i2000² on any of these machines, changed on a six-month schedule, spends the back end of every cycle doing nothing.
And the KM-660MWJ does not clear 180 days even on a Twin. At rated production that machine wants a Triple-i4000², or a Twin on a four-month schedule.
The caveat that makes this honest
These numbers assume the machine runs at its rated 90/70 output every single day. Almost nothing does.
A machine at 60% duty uses 60% of the water and the cartridge lasts about 1.7 times longer. So a KM-520MAJ at 60% duty gets roughly 213 days out of a Single, which does clear six months.
Which is the real lesson: your duty cycle decides this, not the model number. If you know roughly what your machine produces on an average day, use that instead of the rated figure and redo the division. The method is in how often to replace a commercial water filter.
The condenser water trap
If you run a water-cooled model — anything ending MWJ — there is a second number on the sheet that will mislead you badly if you size on it.
| Model | Potable | Condenser | Ratio |
|---|---|---|---|
| KM-350MWJ | 15.5 | 109 | 7× |
| KM-515MWJ | 15.6 | 80 | 5× |
| KM-520MWJ | 14.8 | 75 | 5× |
| KM-660MWJ | 16.1 | 152 | 9× |
A water-cooled KM-660MWJ uses 152 gallons per 100 lb of ice cooling its condenser — nine times what it uses making the ice.
None of that water goes through your filter. Hoshizaki's sheets state that the condenser lines "Must Be Independent of Icemaker." The condenser is cooling a refrigeration circuit; that water never touches the ice and does not need treating.
So size on the potable column only. Adding the condenser figure in would tell you a KM-660MWJ uses 1,124 gallons a day rather than 108, and you would buy roughly ten times the filtration you need. That is an expensive mistake and it is an easy one to make from a spec sheet that prints both numbers side by side.
What to do with this
1 · Find your exact model on the plate, including the last letters. MAJ, MWJ and MRJ are air-cooled, water-cooled and remote — same cabinet, meaningfully different water use. The KM-515MRJ uses 20.5 gal/100 lb against the MAJ's 16.0, which is a 28% difference in cartridge life from one letter.
2 · Estimate your actual daily production. Not the rated figure — what it really makes. If the bin is emptied once a day and holds 300 lb, that is your number.
3 · Do the division. Your gallons per day = production × potable figure ÷ 100. Then cartridge capacity ÷ that = your interval in days. Compare to 180 and take the shorter.
4 · Write the answer on the filter head in marker. It takes two minutes and it survives a change of manager.
5 · Check whether anything shares the line. A fountain or a brewer on the same supply draws from the same cartridge, and none of the arithmetic above accounts for it.
Why we published our own correction
The peak-flow advice we ran for the past two weeks was not wrong in a way that would have hurt anyone — it would have sent a reader looking for a number that does not exist, and they would have given up or asked us.
But this site's entire argument is that we read the documents. Discovering that we had repeated a piece of category folklore without checking it is exactly the thing we keep pointing out in other people's content, and leaving it up while publishing a page built on the correct method would have been the worse option.
Both guides were amended the same day this page went up.
Send us your model and we will do the division
Tell us the exact model off the plate, roughly what it produces on a normal day, and whether anything else is on the same water line. We will tell you which system fits and what your real interval is.
If your duty cycle means a Single is genuinely enough, we will tell you that, and it is the cheaper answer.
Related reading
- Everpure Insurice i2000² vs i4000² — the systems referenced above, and which cartridge each takes
- How often to replace a commercial water filter — the interval method in full
- My ice machine isn't making enough ice — what an exhausted cartridge actually looks like
- The complete water guide for bars, cafés and restaurants — how all of this fits together
Production and water-use figures are from Hoshizaki America's own published specification sheets for the KM-515M_J and KM-350/520/660M_J, archived September 2026. Cartridge capacities are from Pentair Everpure's Insurice specification sheets. The sizing methodology is quoted from 3M's Commercial Ice Machine Filter Sizing sheet. Every cartridge-life figure is our arithmetic from those published inputs, calculated at rated production, and Hoshizaki reserves the right to change specifications without notice.