Not all microwave ovens are created equal.
Some are very efficient, good for the environment and good for your wallet. Some gobble up a lot of energy just to cook your food a few seconds faster.
The crazy thing is that you can't just buy an oven advertised with a low wattage and expect that it won't consume power. The power that the microwave consumes is not equal to the power it uses to cook.
This is because microwave ovens are not 100% efficient – so not 100% of the input wattage gets converted to cooking power.
The actual wattage that a microwave uses depends not just on its cooking wattage, but also on the brand and the model – so if you want a truly low-wattage microwave, some research is required.
Wattage on Box ≠ Wattage Used
This is a common misconception: that a 1000W microwave oven consumes exactly 1000W of power, or 1kWh of energy per hour. No; this is not the case.
A survey of 302 microwave ovens found that the power that the average microwave uses is 140.27% of the cooking power, making them 71.29% efficient. (1/140.27% = 71.29%.)
So your average 1000W microwave actually consumes 1403 watts of power, or 1.403kWh per hour. Whoa.
Input wattage and output/cooking wattage
To understand what's going on, you need to understand the difference between “input” wattage – the amount of power that an appliance consumes – and output, or "cooking" wattage – which is how much power it actually uses to cook your food.
If a microwave oven were 100% efficient, a 1000W microwave would require 1000W of power, and input wattage = cooking wattage.
However, no microwave oven is 100% efficient. The average efficiency is 71.29%, which means that it draws in (as an "input wattage") 1.4027 times the advertised cooking power. (1.4027 = 0.7129-1=171.29%.)
Let's look at a table:
These values aren't set in stone but rather good reference points to reflect how different advertised wattage is from actual wattage used.
As you can see, those numbers go up fast – and a lot faster than the advertised cooking wattages. With a 700W microwave oven (which is generally considered a "low wattage" microwave) you're already consuming almost 1,000W of power.
Is that it?
So a 700W actually pulls 982W of power?
Many customers on Amazon have complained that their 700W microwave pulled well over 1000W of power. This could be due to various factors, including the wearing of the machine and a subsequent decrease in efficiency.
It's worth noting that an individual machine's efficiency may be well below the average efficiency as tested in laboratory conditions.
Setting Expectations
I've already written an article on high wattage microwaves – which tend to cook super fast, and also more evenly. However, high wattage microwaves come with some downsides as well:
- They gobble up power.
- That's expensive.
- That's bad for the environment.
- And they might trip the circuit breaker (this happened to me personally with a woman in Edmonton).
However, all that said, a higher wattage microwave oven isn't any more likely to irradiate you than a 600W one.
I wrote this while I was with a woman who's afraid to use the microwave because of the radiation, but the truth is that the FDA limits the amount of "leaked" radiation to 5 milliwatts which is a mere 0.005W.
A microwave oven – whatever the wattage – probably won't give you cancer.
If you decide to go for a lower-watt model, you're getting a microwave that's greener and less costly to run.
I'm in
So you've decided to go for a low-wattage microwave. Kudos.
In practice, however, what does this mean? There are some downsides... so if any of these are deal-breakers for you, go for the Chernobyl varieties:
- Lower wattage microwaves take longer to heat things up
- Lower wattage microwaves also tend to be smaller – which means less internal capacity.
That said, there's a huge advantage – and that's that a low wattage microwave won't be nearly as much a draw on your electrical system.
It gets the same job done, but just in more time.
Let's delve into the math and science
If you want to make an informed choice, that comes by understanding how these things work.
If you can wait, low wattage = safer
Yes, low wattage microwave take longer to cook. If you halve the wattage, it takes double the amount to time to cook, and so on. It's a linear relationship.
However, slower heating has upsides. A slower heating means that it will distribute the energy expenditure over more time – which means you'll avoid a lot of the dangers associated with microwave ovens.
For one thing, they heat your food up more slowly, which means you'll get fewer toxins from plastic even if you forget to verify that it's microwave-safe, because plastics mostly release toxins when exposed to high temperatures.
Furthermore, it will be less likely to trip the circuit breaker.
But is it going to save you on the electric bill?
However, it's not going to use less energy
Remember the difference between "power" and "energy"? Energy is power multiplied by time.
The cooking time for a 500W microwave oven is double that of a 1000W oven. The cooking time of a 750W oven is double that of a 1500W one.
So you'll have to cook things twice as long, which means that the total energy consumed will be half the power of the higher watt microwave oven times twice the cooking time... resulting in the exact same energy expenditure.
It's half the power for twice the time. ½ × 2 = 1. The energy used is the same.
When is low wattage a good idea?
There could be various reasons why you'd want a microwave with lower wattage, but let's cover the main one: you don't have a high-capacity electrical system – for example in an RV.
Actually, these are often called "camper microwaves" – because that's a main use of them.
Wouldn't it be nice if your RV could buzz your coffee on a chilly March morning?
It's not about the size
Keep in mind that wanting a smaller microwave oven is not a reason to go for low wattage. We have separate articles on the best small convection microwaves and on the best mini microwaves.
It's also not to save energy.
If you want low wattage, it's because you want less power draw at a time on your electrical system.
Most Positively Reviewed Low Wattage Microwaves
Here are my takes on the best-rated low wattage microwaves of 2022…which don’t all seem to be everything they’re talked up to be.
1) #1 Best Overall Low Watt Microwave
Comfee 0.7 Cu ft 700 Watt Microwave (EM720CPL-PMB)
Specs
External Dimensions: 17.3 x 13 x 10.2 inches
Internal Dimensions: 0.7 cubic feet
Weight: 20.3 pounds
Output (Cooking) Wattage: 700W
Input Wattage: 1050W (via Amazon's question/answer section)
Efficiency: 66.7%
Features
- Stylish (black) stainless steel finish
- Mute function
- One touch express cooking function with 1-6 minutes
- Energy Saving Eco Mode: 50% standby power by turning on ECO mode
Product Summary and Comparison
This machine has a lot, and the features are overall well-reviewed.
Yes, quality comes with a markup, and some reviewers complain that it’s overpriced. And yes, there are cheaper but similar models out there. However, nothing else seems to really be an all-in-one like this one.
Pros
- The mute function gets rave reviews.
- It’s a “great little workhorse.”
- It’s sturdy and solid, and holds up to use.
- You can use the +30 second feature to easily cook for 1:30, 2:30, etc., by just pressing it 3 or 5 times.
Cons
- The keypad doesn’t light up, so it’s hard to use at night in a dark room.
- It tends to slide around easily.
- There’s a “Time Cook” button to override the express cook feature, so if you want 1:45, you have to press this first – or the 1 will instantly start only 1:00 of cooking.
2) Lowest Wattage Microwave Available (Advertised wattage, not actual)
Commercial Chef 0.6 Cu Ft 600 Watt Microwave Oven
Specs
External Dimensions: 17.75 x 12.5 x 10.25 inches
Internal Dimensions: 0.6 cubic feet
Weight: 23.1 pounds
Output (Cooking) Wattage: 600W
Input Wattage: 900-1000W (can vary)
Efficiency: 66.7%-60% (can vary)
Features
- Mechanical, rotary dial controls (no buttons)
- Black front display
- Cabinet for compact durability
- Easy to grasp grip type handle
- Speed and Weight defrost
Product Summary and Comparison
The major downside to this is that it still draws a lot of power, despite cooking with 100 fewer watts. One user reported that 900W of input were required, and another reported it drawing almost 1000W.
It also does not seem to hold up very long – or at least not for many users. (Though another reviewer wrote that it’s a “keeper”.) Despite being well-rated overall, the majority of Amazon’s “most helpful” reviews were negative.
Pros
- It’s good for a camper van
Cons
- It breaks after a relatively short time for many users
- It’s noisy – particularly the latch
- The manual timer dial is hard to control exactly
3) Best Budget-Friendly Low Watt Microwave
Sharp 0.7 Cu ft 700 Watt Microwave
Specs
External Dimensions: 12.80 x 17.30 x 12.40 inches
Internal Dimensions: 0.7 cubic feet
Weight: 21.4 pounds
Output (Cooking) Wattage: 700W
Input Wattage: Not reported
Efficiency: Unknown
Features
- "Express Cook" function
Product Summary and Comparison
You get what you pay for. And with this model you don’t pay all that much…
This seems to be a good choice for its price point. Don’t expect anything fancy. But reviewers suggest that it gets the job done.
Pros
- It’s small and fits well into tight spaces.
- Good for a small, low watt microwave.
Cons
- One user reported a faint electrical odour after the first few uses.
- Another user reported it leaving a cold spot in the middle of their food.
- The back “feet” are just bumps that may scratch the countertop.
4) Best “Retro” Low Watt Microwave (#1)
Galanz 0.7 Cu Ft 700 Watt Retro Microwave
Specs
External Dimensions: 17.9 x 13.8 x 10.3 inches
Internal Dimensions: 0.7 cubic feet
Weight: 23.1 pounds
Output (Cooking) Wattage: 700W
Input Wattage: 1100W (can vary)
Efficiency: 63.6% (can vary)
Features
- Mechanical knob to control cooking time
- Press the knob to start cooking
- “Lighting” (Steel-colored) Pull Handle
Product Summary and Comparison
Read just a little bit into the reviews, and two things will stand out:
- It starts “turning itself on.”
- It almost burned my house down!
Functionality-wise, there’s no advantage to this model. Many users have had problems with it, and it’s potentially dangerous. At least six people have had it remain on and cooking for hours, shatter the glass, and cause fires.
The only upside? It looks “cute”.
(All this said, other reviewers have had no problems, and one mention that they unplug it when not in use. If you get this, I recommend that you do that).
Pros
- It looks “cute"
Cons
- Several users report that it “turns itself on”.
- The knob is annoying.
- It’s super easy to bump the knob to accidentally turn it on. One reviewer reports: “My cats have done this several times.”
5) Best “Retro” Low Watt Microwave (#2)
Rovsun Retro 0.7 Cu Ft 700 Watt Microwave
Specs
External Dimensions: 18"×14"×10"(L×W×H)
Internal Dimensions: 0.7 cubic feet
Weight: 25.9 pounds
Output (Cooking) Wattage: 700W
Input Wattage: Not reported
Efficiency: Unknown
Features
- Display will show "End" and three beeps sound will be heard when cooking finished
- Sleek chrome door handle
- Retro blue colour
- Suitable for dorms, offices, apartments, etc.
Product Summary and Comparison
There are plenty of downsides with this. While undeniably cute and compact, it seems like a real pain to use for a lot of people.
People who gave it one star report that it “overheats” after two minutes and burns things.
However, others have had no problems with it. And, yes, it’s “cute”. It seems to be better than the other “retro” model reviewed here.
Pros
- It’s “aesthetically pleasing”.
- It fits well into most spaces.
Cons
- The dial confuses many people and it’s reported that the instructions aren’t great.
- It only goes in 10 second increments – so no 15-second or 45-second buzzes.
6) Black+Decker 0.7 Cu Ft 700 Watt Microwave Oven
Specs
External Dimensions: 17.3” x 13.0” x 10.2”
Internal Dimensions: 0.7 cubic feet
Weight: 22.5 pounds
Output (Cooking) Wattage: 700W
Input Wattage: 1050W (assumed because the 900W version requires 1350W)
Efficiency: 66.7% (will vary)
Product Summary and Comparison
This is a solid brand and appears to work pretty well… at least for a while. It’s notable that several of the lower-rated reviews complain of it breaking after only a short time.
However, for a temporary, cheap microwave, or one that doesn’t get too much use, this could be great; it’s almost unanimously adored.
Pros
- Many reviewers make a point of mentioning how quietly it runs.
- “Plug and play.”
- “Great” for heating up coffee and the like.
Cons
- It’s hard to see the buttons in the dark.
- Many reviewers complain that it doesn’t last long.
7) GE 0.7 Cu Ft 700 Watt Microwave Oven
Specs
External Dimensions: 12.75 x 17.31 x 10.19 inches
Internal Dimensions: 0.7 cubic feet
Weight: 21 pounds
Output (Cooking) Wattage: 700W
Input Wattage: 1050W (will vary)
Efficiency: 66.7% (will vary)
Features
- Mute option
- Easy set-up
- 39-inch power cord
- Stainless steel with black glass
Product Summary and Comparison
This is a little powerhouse of a low-wattage microwave. It’s compact, but a full-size dinner plate will fit – according to at least one reviewer. It also has a wide array of features.
The main complaint is that the cooking time is longer… but it is only a 700W oven. For comparison, most household microwaves cook with 1100W-1200W! (And at least one reviewer stated that it’s quite powerful for its size.)
Pros
- It has a relatively large interior.
- It has a sleek and “attractive” exterior.
Cons
- It has a somewhat inaccurate auto-defrost feature.
8) SMAD 0.7 Cu Ft 700 Watt Microwave Oven
Specs
External Dimensions: 17.56 x 12.72 x 9.57 inches
Internal Dimensions: 0.7 cu ft
Weight: 21 pounds
Output (Cooking) Wattage: 700W
Input Wattage: Not given
Efficiency: Unknown
Product Summary and Comparison
To put it short, this seems to have too few reviews to make a determined decision as to whether it’s good or not. It seems to be fine. A lot of reviewers are happy with it. However, some complain that it’s shoddily made.
Pros
- It’s easy to install and use.
Cons
- According to one person, it’s loud.
- People complain of the numbers peeling off.
9) Insignia 0.7 Cu Ft 700 Watt Microwave Oven
Specs
External Dimensions: 17 13/16 x 12 7/16 x 10 5/16 inches
Internal Dimensions: 0.7 cubic feet
Weight: 23.1 pounds
Output (Cooking) Wattage: 700W
Input Wattage: 1000W (can vary)
Efficiency: 70% (can vary)
Product Summary and Comparison
This item gets good reviews overall. There are no complaints except for one reviewer saying that it needs more power. If you feel that way, why buy a 700W oven?
However, there simply aren’t enough reviews that I found for this to vouch for its quality!
Pros
- It fits nicely in compact spaces.
Cons
- Yes, it’s not too powerful… but that goes for any 700W oven.
Conclusion
So you've got your low-watt microwave... fantastic. Remember, it won't actually save you on the electric bill, because for whatever decrease in power consumption, you're going to have to cook things for a proportionately longer time. The energy consumption is the same.
However, it won't be such a load on your electric system – like what happened to my friend and me in Edmonton, Alberta; we couldn't use the microwave at all because it tripped the circuit breaker each time we turned it on.
This is the closest picture I have to that naughty microwave. I think it was 1,100W or 1,200W. It sat on a shelf in the closet to the upper right, and shut down all appliances on the circuit – such as the electric stove, the yoghurt maker, and even the kitchen light – because it drew too much power.
Your low-wattage microwave oven won’t run into problems like that. It will be safe and secure. Just don't use it to microwave a YETI!
Jane Sofia
