A microwave is one of the most-used appliances in any kitchen, but a full-size unit is a poor fit for an RV galley or a small apartment counter. It eats space you do not have and draws more power than a 12-volt or limited-amperage setup can comfortably handle. The answer is a compact microwave sized for tight spaces and modest electrical systems. This guide covers the dimensions, wattage, and mounting choices that matter, plus the practical details that separate a microwave that works in your rig from one that trips your breaker or never fits the cabinet.
Size and Capacity: Measure Before You Buy
The single most common mistake is buying a microwave that does not fit. RV cabinets and apartment counters have hard limits, so measure the opening in all three dimensions before you shop, and leave clearance for ventilation at the back and sides. Compact microwaves generally run from about 0.5 to 0.9 cubic feet of interior space. A 0.7 cubic foot unit is the sweet spot for most RVs and small kitchens, fitting a dinner plate or a standard bowl without dominating the counter.
Pay attention to the turntable diameter, not just the cubic-foot rating. Some compact units have a small turntable that will not rotate a large plate, which forces you to stop and reposition food halfway through heating. If you regularly reheat full meals, confirm the plate you actually use will spin freely inside the cavity.
Wattage and Power Draw: The RV Dealbreaker
Microwave wattage describes two different things, and confusing them leads to disappointment. Cooking wattage is the heating power delivered to your food, typically 600 to 800 watts on compact units. Input wattage is the electrical power the unit pulls from your outlet, which is always higher, often 1,000 to 1,300 watts. For RVers, the input figure is what matters because it determines whether the microwave runs on your electrical system.
A microwave pulling 1,200 watts needs roughly 100 amps from a 12-volt battery bank through an inverter, which is a serious load. If you run a microwave off-grid, you need a pure sine wave inverter rated well above the unit's input wattage to handle the surge at startup. A properly sized inverter and battery setup from Victron Energy makes running a microwave off solar and lithium realistic rather than a battery-draining gamble. If you only ever run on shore power or a generator, a standard 800-watt cooking unit on a 15-amp circuit is fine, but always check that the input wattage fits within your available amperage.
Countertop vs. Built-In vs. Convection
Compact microwaves come in a few configurations, and the right one depends on your space and how you cook. A countertop unit is the cheapest and simplest, but in a moving RV it must be secured so it does not slide or fly off the counter in transit. Many RVers build a recessed shelf with a retaining bar or strap for exactly this reason. A built-in microwave is designed to mount flush in a cabinet, giving a clean look and freeing counter space, which is why most factory RV installs use them. They cost more and require proper ventilation clearance.
A convection microwave adds a heating element and fan so the unit doubles as a small oven, baking and roasting in addition to microwaving. For RVers without a separate oven, this is a genuine space-saver, letting one appliance handle far more cooking. The trade-off is higher power draw in convection mode and a higher price. If your galley is tight and you want to bake without a dedicated oven, the convection feature usually justifies the cost.
Features That Earn Their Keep
Most microwave features are marketing, but a few genuinely help in a compact unit. Sensor cooking adjusts time automatically based on humidity from the food, which prevents the overcooking that plagues guesswork in a small cavity. One-touch presets and a defrost-by-weight function speed up everyday use. A child lock is worth having if you travel with kids or want to prevent accidental starts while driving.
Pay attention to the door and controls, too. A push-button door release can be easier to operate in a cramped galley than a handle, and a flat membrane keypad wipes clean far more easily than recessed buttons in the dusty environment of an overlanding rig. Skip gimmicks like grill racks and elaborate menu trees you will never use. In a compact unit, reliability and simple operation matter more than a long feature list.
Installation, Ventilation, and Safety
A compact microwave needs airflow to shed heat, so never box it into a sealed cabinet without clearance. Follow the manufacturer's minimum gaps at the top, sides, and rear, and make sure the rear vents are not pressed against a wall. In an RV, this clearance also matters for the unit's longevity in a hot, vibration-heavy environment.
Secure any countertop unit for travel. Vibration and hard braking will move an unsecured microwave, and a falling appliance can injure someone or damage the galley. A simple retaining strap, a recessed shelf, or a non-slip mat combined with a bar across the front solves this cheaply. Finally, mind your circuit. Do not run a high-wattage microwave on the same circuit as your air conditioner or other heavy appliance, since the combined draw will trip the breaker. Knowing your microwave's input wattage and matching it to your electrical capacity is the difference between a smooth install and a frustrating one.
The Bottom Line
Choosing a compact microwave is mostly about two numbers: the physical dimensions of your space and the input wattage your electrical system can handle. Measure your cabinet or counter in all three dimensions, confirm a real plate fits the turntable, and check the input wattage against your available amps before anything else. For shore-power and apartment use, a simple 0.7 cubic foot, 700 to 800-watt countertop unit covers nearly everyone. For off-grid RVing, size your inverter and battery bank to the microwave's surge, or consider a convection model to replace a separate oven and earn its space. If you are building out the electrical side to run a microwave reliably off-grid, start with a well-matched inverter and power system and pair it with the right RV galley appliances for your build.