The hopper figure only means something next to the portion figure

Portions arrive in a mix of units: fractions of a cup for Whisker and PetSafe, grams for WOpet and PETKIT, and a count of portions for iPettie. Days between refills is capacity divided by what you dispense per day, and that division only works when both figures share a unit.

Whisker complicates its own figure by publishing two. The Feeder-Robot holds up to 32 cups without the hopper insert and up to 25 cups with it, and the insert ships in the box. Arf Pets publishes 29 cups, so the order between these two flips depending on whether the Whisker insert is installed. Of the three feeders stated at 5L, only iPettie adds an equivalent, 170 oz or about 21 cups; PETLIBRO and PETKIT publish the liter figure alone.

Working out days between refills

Take the manufacturer’s portion unit and the schedule you plan to run, and multiply. Whisker dispenses up to 1/2 cup per meal in 1/8-cup steps, across up to 8 scheduled meals. Every slot at maximum draws 4 cups a day, which empties the 32-cup hopper in 8 days and the 25-cup insert configuration in about 6. One cat fed 1/4 cup twice a day draws 1/2 cup, and the same hopper runs for about two months.

PetSafe’s range is 1/8 cup to 4 cups per meal across up to 12 meals. A dog fed 2 cups twice a day takes 4 cups, so the 24-cup hopper lasts 6 days. Add a cat at 1/4 cup twice a day and the total rises to 4.5 cups, which brings it to just over 5 days.

WOpet gives you a weight to work with. Its 7 lb (about 3.2 kg) of dry food, dispensed through the large wheel at the 390g (13.8 oz) ceiling four times a day, lasts about 2 days.

For PETKIT, PETLIBRO and iPettie the sum cannot be finished from published figures alone, because the hopper is stated in liters and the portion in grams. iPettie publishes its portion as a count split between two bowls, but nothing in its listing says how many grams a full hopper of your kibble weighs. You would need to weigh a full hopper yourself before you can predict a refill interval.

Separation is a hardware feature or it is not there

Only two feeders in this group put two bowls in the box. The PETLIBRO Granary 2 Vision Duo has two independent dispensing chutes, a scale under each bowl accurate to about 1g, and a camera that recognizes individual cats and logs which pet ate at which bowl. PETLIBRO states the two channels dispense within 5% of each other, which separates and records the two bowls; nothing PETLIBRO publishes says one bowl can be given a different portion from the other. The iPettie W5 uses a built-in 2-way splitter that divides every dispensed meal between two included stainless steel bowls on three height settings.

PetSafe sells a 2-Pet Meal Splitter with its own bowl for the Smart Feed, as a separate purchase. Whisker’s own guidance on feeding multiple cats says the Feeder-Robot cannot identify which cat approached the bowl or track per-cat consumption; it can schedule separate times, and that is the extent of it. WOpet, PETKIT, Arf Pets and Cat Mate publish no splitter or recognition feature at all.

The floor and the ceiling from one machine

A cat-and-dog household needs a small portion and a large one from the same dispenser. Whisker goes from 1/8 cup to 1/2 cup, which covers the cat side and stops well short of a large dog’s meal in a single dispense. PetSafe goes from 1/8 cup to 4 cups, the widest cup-based span here, and adds a Slow Feed setting that spreads a larger portion over 15 minutes.

WOpet’s range is the widest in grams, but it comes from two included interchangeable wheels rather than one setting; the figures for each wheel are in the table. PETKIT’s single mechanism reaches 200g per meal, so it slightly exceeds the WOpet small wheel’s ceiling without a hardware swap but cannot approach the large wheel’s.

Cat Mate has no portion control. Each of its five compartments dispenses whatever a person placed in it, up to 11.5 oz (330g), so the portion is as fine as your measuring cup and no finer. PETLIBRO and Arf Pets publish no portion figures for the models here, which in PETLIBRO’s case is the single biggest gap in an otherwise detailed series page.

Fixed slots versus freeform times

PetSafe’s 12 meals a day is the highest published ceiling. iPettie and PETKIT both publish 10, and Whisker publishes 8 plus on-demand snacks.

WOpet and Cat Mate both stop at 4. WOpet’s are named slots, Breakfast, Lunch, Dinner and 4th Meal, each switched on or off independently. Cat Mate’s are four programmed times plus one bowl filled immediately at setup. Both set times in 10-minute increments, so a 7:05 meal is not available on either. PETLIBRO and Arf Pets do not publish a maximum.

What keeps meals coming when the power drops

Whisker’s 12V backup battery is sold separately; without it the unit has no battery power, per Whisker’s product page.

Four feeders take disposable cells that are not in the box. PetSafe uses 4 D-cells and publishes no runtime. iPettie uses 3 C-cells and publishes no runtime. WOpet uses 3 D-cells and says a set typically lasts about a year, but its manual does not say whether the unit switches to them automatically during an outage. Arf Pets uses 3 D-cells strictly as backup and states that on batteries alone the last saved schedule keeps running without app access.

Cat Mate is the outlier. Its 3 AA batteries are the only power source, with no AC adapter option, and Pet Mate says good-quality alkaline cells normally last about 12 months.

Kibble size and wet food

Three feeders publish a maximum kibble size. Whisker takes dry or semi-moist kibble up to 5/8 in (16mm). iPettie takes dry or freeze-dried food from 0.12 to 0.51 in (3mm to 13mm). PETKIT takes kibble up to 0.47 in (12mm) and also lists freeze-dried and air-dried food. Arf Pets states dry kibble only, with no maximum diameter.

Cat Mate is the only one of the eight that accepts wet food. No hopper feeder in this group publishes wet-food support, and Arf Pets excludes it in writing.

When the timer-only feeder is enough

WOpet’s and Cat Mate’s manuals describe no app, WiFi or account requirement, with meal times set on the unit. They are enough when one pet, or two pets that already share a bowl, eat at most four times a day and nobody needs a low-food alert on a phone. WOpet is the one to choose if the portion must be measured in grams; Cat Mate is the one if the food is wet or the feeder must never depend on a wall outlet.

They are not enough when the schedule needs more than four slots, when two pets need separate bowls, or when you want to know from elsewhere that the hopper is running low. PetSafe publishes low and empty food alerts; iPettie publishes feeding records and multi-user sharing; PETLIBRO and Arf Pets add a camera. PetSafe, iPettie and Arf Pets each state a 2.4GHz-only WiFi requirement; Whisker and PETLIBRO publish no band. PETLIBRO’s alerts when a pet’s eating habits change require Petlibro Care, and its 24/7 recording and playback require the separate Video Cloud AI subscription.

Warranty terms run from PetSafe’s 45-day satisfaction guarantee, which is a return window rather than a product warranty, through 1 year for Whisker, Arf Pets and PETKIT, 24 months for PETLIBRO, to Cat Mate’s 3 years, which requires registering within 14 days of purchase.