What size garbage disposal do I need?

Two big disposal makers publish guides, and they don't match exactly. Here is what each one says.

Waste King's selection flyer works from household size and whether you cook often. It points 1 to 2 people to 1/3 horsepower, 2 to 4 people to 1/2 or 3/4 horsepower, and 4 or more people to 1 horsepower. Each option comes with a use level: light for 1/3, medium for 1/2, medium to heavy for 3/4 and heavy for 1 horsepower.

Moen calls its chart a general reference guide, and its bands overlap on purpose. Both makers say the same thing in different words: more people and more cooking call for more power.

A useful way to read the two charts together is to ask which end of the range you fall on. A couple who eats out often can stay near the bottom of the range. A family that cooks from scratch, or a household that hosts often, belongs near the top.

Horsepower decides how tough a scrap the motor can handle. Waste King's selection guide gives a plain ladder:

• 1/3 horsepower: light use, for soft food, fruit rinds, cereal and meat trimmings.
• 1/2 horsepower: medium use, for scraps and leftovers such as potato peels, celery, cooked meat or fish, seeds and small bones.
• 3/4 horsepower: medium to heavy use, for tougher scraps such as artichokes, vegetable peels, cooked meat or fish, fruit pits and small bones.
• 1 horsepower: heavy use, for all food scraps including fibrous foods, raw or cooked meat or fish, fruit pits and small bones.

Moen says the same thing from the other side. It explains that the unit's rated power determines what it can effectively grind, that smaller units "are not intended to pulverize bones or process fibrous materials like husks," and that those items "can become lodged or wrapped around internal components." That is why an undersized disposal jams more. If yours jams often, see what a humming garbage disposal means.

InSinkErator sorts its lineup by what the disposal can take. Its Badger series handles everyday food scraps, its Power series is "designed for tough food scraps like peach pits," and its Advanced series is "engineered for tougher and fibrous food scraps like bones, celery, and corn cobs." All series share one rule: never put fats, oils or grease into the disposal. The company also says proper use matters as much as the model, and its steps are to turn on cold water, turn on the disposal, feed waste in gradually and let the water run a few seconds after grinding stops. It also says not to preload the disposal.

Horsepower is the easy part. These checks catch problems before installation day.

### Will it fit in the cabinet?

Moen tells shoppers to measure before buying. Consider the height between the sink and the cabinet floor, the width of the disposal, and where your current pipes line up. It lists three measurements that matter: from the top of the disposal to the center of the dishwasher connection, from the top to the center of the drain pipe connection, and from the top to the bottom of the disposal. Check them against the specification sheet for the model you want. A taller, more powerful disposal can have its drain outlet sit lower than your existing trap, and that can force a plumbing change.

### Does the mounting match your sink?

Mounting is a common reason a swap goes wrong. Moen says its Universal Xpress Mount fits all Moen and most existing three-bolt mounting assemblies. Waste King says its disposals fit standard sink holes, which it describes as typically 3 1/2 inches. If your old sink flange is cracked or corroded, replace it when you swap the unit, since the flange holds the whole disposal up.

### How will it be switched on?

Moen describes two ways. A continuous feed disposal grinds as long as its switch is on, so it needs a wall switch or an air switch. A batch feed disposal turns on when you seat a stopper in the opening and stops when you take it out. Waste King says batch feed disposals suit kitchens without a wall switch and give a safer grind, since they run only when the stopper covers the opening. Waste King also says its units work with an air switch, which uses a control module plugged into a dedicated grounded 120 volt outlet, with no wall switch or hardwiring needed.

### How is it powered?

Some disposals plug into an outlet under the sink, and others are hardwired to the house circuit. Waste King's installation sheet says its EZ Mount unit is designed for 110 to 120 volts at 60 hertz "exclusively." Another voltage will hurt performance. The same sheet says that if you're not familiar with electrical power and procedures, you should call a qualified electrician. If your sink has no outlet, adding one or wiring the unit is electrical work, so plan for it.

### Will it connect to your current pipes?

Waste King says that when you are replacing a disposal, the existing plumbing connections to your waste pipe should support any model or manufacturer. A first-ever install where there was never a disposal needs a connection kit from a plumbing supply store. That is a reasonable line between a simple swap and a job with new plumbing.

### Does the dishwasher hook up?

If a dishwasher drains through the disposal, check the hose. Waste King says its disposals accommodate 7/8 inch internal diameter dishwasher hoses, and that a different size needs a connector kit. Our page on why a disposal leaks explains what goes wrong at that inlet, including the knockout plug that must be removed first.

Five quick checks get you to the right disposal, and they take about ten minutes with a tape measure.

1. 1Count the people in your household and note how often you cook from scratch.
2. 2Pick the horsepower from the charts above. When you land between two sizes, go up one, especially if you grind tough scraps.
3. 3Measure the cabinet, the drain height and the dishwasher connection.
4. 4Confirm the switch type and the power source.
5. 5Check the mounting against your sink flange.

A plumber earns the call when the swap involves anything beyond lifting one unit out and dropping another in. That means a new outlet or a hardwired connection, a trap or drain that no longer lines up, a cracked flange or a kitchen with no dishwasher inlet yet. HQ is licensed and insured, gives free estimates and upfront pricing, and can size the unit to how you cook. If your current disposal is failing, where the reset button is is worth a look before you replace it.

Once you have picked a size, how to replace a garbage disposal covers the removal and mounting, and how to maintain a garbage disposal so it lasts covers the care that keeps the new one running.

Sink gauge affects how well it holds a disposal; see the best material for a kitchen sink.