Wattage is the single most important number on a microwave's spec sheet, yet most shoppers ignore it. An 800W model reheats a bowl of soup in roughly 2 minutes on the UK's 240V mains supply, while a 600W machine takes closer to 3. Get the wattage wrong and you'll spend years fighting undercooked middles and overcooked edges.
What to look for
01Wattage and real-world cooking speed
Microwave wattage is a direct measure of how quickly the magnetron converts electricity into heat. At 800W, a standard 300g portion of leftover pasta reheats evenly in about 2.5 minutes. Drop to 700W and that climbs to roughly 3 minutes; at 600W you're looking at 4 minutes or more. For a busy household heating multiple portions back-to-back, those extra minutes add up fast. The two Toshiba and both Russell Hobbs models in this guide all run at 800W, which is the practical minimum worth buying in 2026. Anything below 700W is really only suitable for a student bedsit or a caravan. Above 1,000W you move into combination-oven territory, which is useful but adds cost and bench space. On the UK's 240V supply, an 800W microwave draws around 1.2–1.4 kW from the wall once inverter and magnetron losses are factored in, so running costs remain modest at current energy prices.
02Power levels and what they actually do
A microwave's power levels don't reduce wattage continuously; they cycle the magnetron on and off. At 50% power on an 800W machine, the magnetron fires for roughly half of each 30-second window. This matters most for defrosting and gentle reheating, where constant full power would cook the outside before the centre thaws. The Russell Hobbs RHM2076B offers 5 power levels, which covers every practical scenario: full power for reheating, 70–80% for cooking dense vegetables, 50% for defrosting, and 30% for softening butter or melting chocolate. The Toshiba MM-EM20P steps up to 11 power levels, giving finer control that's genuinely useful if you cook fish or egg-based dishes regularly. For straightforward reheating and defrosting, 5 levels is plenty. If you're using the microwave as a primary cooking tool rather than a reheating convenience, the extra granularity of 11 levels is worth the small price premium.
03Cavity size and kitchen fit
Both the Russell Hobbs and Toshiba models here offer a 20-litre cavity, which comfortably fits a standard 25cm dinner plate and is the most common size sold in the UK. Measure your worktop gap before buying: a 20-litre solo microwave typically measures around 440–460mm wide and 340–360mm deep, so it fits neatly on a standard 600mm-deep UK kitchen worktop with room to spare at the back for ventilation. If you're placing it inside a cabinet, check the manufacturer's clearance requirements, usually 75–100mm on each side and above. Going up to a 25-litre or 30-litre model adds roughly 50–80mm to each dimension and may not fit under standard 500mm wall-cabinet clearances. For most UK kitchens, 20 litres at 800W is the sensible default.
04Hard water and interior cleaning
In hard-water areas, which covers most of southern and central England, limescale builds up inside the cavity faster than you'd expect, particularly around the steam vents and on the ceiling. All four microwave models here advertise easy-clean interiors, typically a smooth acrylic or enamel coating that wipes down without abrasive cleaners. A practical tip: place a microwave-safe bowl of water with a slice of lemon inside and run it on full power for 3 minutes. The steam loosens splatter and the citric acid helps dissolve light limescale deposits. Avoid abrasive pads on any interior surface, as scratches harbour bacteria and accelerate corrosion. If you're in a hard-water area, a quick wipe-down after every few uses will extend the life of the cavity coating significantly.
Our top picks
Best for everyday reheating on a budgetRussell Hobbs RHM2076B 20 Litre 800
Currently £78.99, with a 90-day low of just £23.00, the Russell Hobbs RHM2076B is worth watching for a price drop. At 800W across a 20-litre cavity, it covers all the basics: 5 power levels, automatic defrost, and 8 auto-cook menus. Over 20,000 Amazon UK reviews averaging 4.6 stars suggest it holds up well in daily use. The black finish suits darker kitchen schemes and the digital display is clear enough to read across a typical UK kitchen.
Best for stainless-steel kitchen aestheticsRussell Hobbs RHM2076S-AZ 20 Litre 800
The silver RHM2076S-AZ is mechanically identical to its black sibling, delivering 800W into a 20-litre cavity with the same 5 power levels and 8 auto-cook menus, but its brushed-silver finish blends with stainless-steel appliances far more convincingly. At £78.99 with a 90-day low of £40.00, it's worth setting a price alert. The 4.6-star average across nearly 21,000 UK reviews is one of the most reliable satisfaction signals in this category.
Best value 800W solo microwaveTOSHIBA 20 Liter 800W Manual Control
At £54.98, the Toshiba MM-MM20P(WH) is currently the cheapest 800W, 20-litre option here, sitting well below its 90-day high of £69.99. Manual dial controls mean fewer electronics to fail, and the 5 power levels handle defrost and reheat duties without fuss. The white finish suits lighter kitchen schemes. With over 10,000 UK reviews at 4.3 stars, it's a proven performer for anyone who wants reliable 800W output without paying for a digital interface.
Best for precise cooking with 11 power levelsTOSHIBA 20 Liter 800W Digital Solo
The Toshiba MM-EM20P(WH) costs £67.97 and adds a digital display, 11 power levels, and 6 one-touch preset recipes over the manual Toshiba. The 11-level power control is genuinely useful for fish, custards, or anything that scorches at full 800W. Its 90-day high was £79.99, so the current price represents reasonable value. At 20 litres and 800W, the cavity and output match the Russell Hobbs models, but the finer power increments give noticeably better results with delicate ingredients.
Frequently asked
What wattage microwave do I need for a UK home?
For most UK households, 800W is the practical sweet spot. It reheats a standard portion in 2 to 3 minutes on the 240V mains supply, handles defrosting reliably, and keeps running costs low. Models below 700W are noticeably slower and better suited to occasional use in a bedsit or office. If you cook regularly in the microwave rather than just reheating, consider 900W or above, but be aware that cavity size and price both increase at higher wattages.
Does higher wattage mean higher electricity bills?
Marginally, but the effect is smaller than most people expect. An 800W microwave draws roughly 1.2 to 1.4 kW from the wall. Running it for 10 minutes a day costs approximately 2 to 3 pence at current UK unit rates. A 1,000W model used for the same time costs perhaps half a penny more per day. The bigger factor is how often you use it, not the wattage difference between similarly sized models.
Is 20 litres big enough for a family microwave?
A 20-litre cavity fits a standard 25cm dinner plate and handles single portions comfortably, but it can feel tight when reheating a large casserole dish or a family-sized bowl. For a household of three or more people regularly heating large dishes, a 25-litre model gives noticeably more room. For one or two people, or for anyone mainly reheating individual portions, 20 litres at 800W is perfectly adequate and takes up less worktop space on a standard 600mm-deep UK kitchen counter.
What do microwave power levels actually do?
Power levels on a microwave cycle the magnetron on and off rather than reducing its output continuously. At 50% power on an 800W machine, the magnetron runs for roughly half of each cycle. This is important for defrosting, where constant full power cooks the outside before the centre thaws, and for gentle tasks like softening butter or melting chocolate. Five power levels covers every common scenario. Eleven levels, as on the Toshiba MM-EM20P, gives finer control that benefits fish, eggs, and other heat-sensitive foods.
How do I clean the inside of a microwave in a hard-water area?
Fill a microwave-safe bowl with 300ml of water and add a few slices of lemon or a tablespoon of white vinegar. Run it on full power for 3 minutes, then leave the door closed for another 2 minutes to let the steam work. Wipe the interior with a soft cloth. The citric acid or acetic acid helps dissolve light limescale deposits common in hard-water areas across southern and central England. Avoid abrasive scourers, which scratch the cavity coating and make future cleaning harder.