Best Electric Heater for Each Room UK: Sizes & Wattage Guide

Most British homes are heated as one block: one boiler, one thermostat, one bill. The problem is that British homes are not one block. A Victorian terrace with a 20 m² lean-to conservatory, a converted garage gym and a box room used as a study has at least three spaces the central heating either cannot reach or should not be asked to reach.

The fix is usually not a bigger boiler. It is a correctly sized electric heater in the two or three rooms you actually use during the day.

The short answer: match wattage to the space, not to the room's name. As a working rule, allow roughly 100W per m² for an insulated room with modern glazing, and 150–200W per m² for a conservatory, a single-glazed period property, or any unheated outbuilding. That puts a 1,000W heater in a hallway or spare bedroom, a 1,500W unit in a typical 10–15 m² home office, and a 2,000W unit in a living room, garage or glazed conservatory.

This guide takes the seven spaces UK households most often try to heat on their own — and shows what actually works in each.

Quick picks at a glance

Before You Buy: The One Terminology Trap UK Buyers Fall Into

In Britain, "storage heater" has a specific meaning: a heavy, brick-filled unit that charges overnight on an Economy 7 tariff and releases heat during the day. This is a different product with a different use case, and shoppers searching for it will leave your page if you use the term too loosely.

The heaters in this guide are ceramic-core (inertia) panel heaters. They store heat in a dense ceramic element, release it steadily, and operate on a normal single-rate tariff — no off-peak meter required. Compared with an old night storage heater, they offer genuine practical advantages: heat available on demand, room-by-room control, and no need to predict the next day's weather the night before.

If you are on a standard variable tariff, the current average electricity unit rate in Great Britain under the Ofgem price cap for October to December 2026 is 26.32p per kWh, with a daily standing charge of 54.83p, based on typical direct-debit use (Ofgem, 2026). All running-cost figures below use this rate, rather than last winter's.

1. Conservatories: The Coldest Room in the House (Conservatory Heaters)

From a thermal perspective, a conservatory is a glass box attached to a wall. Its roof and three glazed elevations cause heat loss at several times the rate of an internal wall, making the room uncomfortably hot in July but unusable by November. Most UK conservatories were also built without any heating provision, as planning rules historically discouraged extending the central heating circuit into them.

What works: fast convection, used only when you are in the room. Convector heaters circulate air throughout the entire space rather than heating a single spot. This is why a 2,000W convector can make a 12 m² conservatory usable within 15–20 minutes, whereas a 1,000W panel heater could take well over an hour.

Best choice: 2,000W black Smart X aluminium convection heater, floor-standing. The aluminium body heats up and cools down quickly, avoiding wasted warm-up time. With castors, it can stay in the conservatory from October to March and move to the garage or spare room for the rest of the year — one appliance for two seasons.

Alternative: 2,000W white ceramic-core wall heater (smart or standard). If the conservatory has a solid dwarf wall, wall-mounting keeps the floor clear and positions the heat source below the cold glazing, where draughts actually form. The ceramic core continues releasing heat after the thermostat switches off, helping offset the constant radiant heat loss through the roof.

Be realistic about size. A 2,000W heater will take the chill off a 3 × 4 m conservatory and keep it comfortable for evening use. It will not transform a 25 m² orangery into a living room in January. If your conservatory contains more than approximately 12 m² of heavily glazed space, plan for two units or accept that it will be used seasonally.

2. Garages, Sheds and Garden Offices: The Spaces the Boiler Never Reached

The role of the traditional British shed has changed. It is now used as a gym, a workshop, a man cave, a pottery studio, or — since hybrid working became widespread — a garden office equipped with a monitor and a ring light. What has not changed is the building itself: single-skin brickwork, a timber frame, no cavity insulation, no radiator, and a door that opens directly onto a cold garden.

Best choice: 1500W or 2000W standard white ceramic-core wall heater. Choose 1500W for a well-sealed shed measuring 8–12 m², and upgrade to 2000W for a single-skin garage, a double-width workshop, or any space where the door is opened regularly. Ceramic heat is both radiant and convective, warming the person at the workbench rather than just the air near the ceiling. It also does not dry out the air in the way a fan heater does, which is important in a workshop where both timber and paperwork respond to humidity.

Add-on for gyms and cold starts: 2,000W black Smart X convection heater on castors. Use it for the first 20 minutes before a workout, then let the wall-mounted unit maintain the temperature. This is the most economical way to make an uninsulated garage usable in February without running a 2,000W appliance at full power for three hours.

Practical note: Install the heater in accordance with the manufacturer's instructions, observing the specified mounting height and clearance requirements. Keep it well away from stored paint, solvents, petrol cans and other combustible materials. Fixed wall heaters should be securely mounted, and their installation should be treated as a permanent electrical installation rather than a portable heating setup.

3. Home Offices: Heating One Person, Not One House

Hybrid working means the average British home office is occupied three days a week by exactly one adult, sitting still, in a room of 8–15 m². Heating the whole house for that is indefensible: a gas boiler cycling to warm six radiators so that one person's shoulders stay warm is the single most common waste we hear about.

What works: a 1,000W or 1,500W smart ceramic-core wall heater on a scheduled timer.

Best choice: 1,000W (up to ~10 m²) or 1,500W (10–15 m²) smart white ceramic-core wall heater. The 7-day / 24-hour programme is the feature that pays for itself: set it to reach temperature at 08:45 on Monday to Wednesday, off on Thursday and Friday if you commute, and a lower setpoint at weekends. You arrive to a warm room rather than waiting 40 minutes for one.

4. Bedrooms: silence and stable temperature, above all

British bedrooms are small, often the coldest rooms in the house after the conservatory, and the room where heater design matters most — because you are asleep and cannot adjust anything. Two complaints dominate: noise and dryness.

What works: a low-wattage ceramic-core panel with open-window detection.

Best choice: 1,000W or 1,500W smart white ceramic-core wall heater. A 1,000W unit is the right size for a single or spare bedroom up to about 10 m²; 1,500W suits a master bedroom of 12–15 m² or any room with two exposed walls.

• Open-window detection is the standout feature for UK homes. Older British housing stock has a well-documented damp and mould problem, and the standard remedy — throw the windows open for ten minutes every morning — dumps all the heat you paid for straight outside. The heater senses the sudden temperature drop, cuts output, and resumes when the window closes. On a 1,500W unit running an hour a day through winter, that behaviour is worth more than any smart-home gimmick.
• Keep the thermostat at 16–18°C overnight, and use the timer to drop to a lower setpoint 30 minutes after your usual bedtime rather than heating an empty room until morning.

5. Living Rooms: Where Looks Matter As Much as Watts

The living room is the largest space most households heat independently — 15–25 m² is typical — and the one where a heater is on display. British buyers are unforgiving here: a white plastic box on a bracket will be rejected in favour of a cast-iron radiator, even at twice the running cost.

What works: either a design-led convector for speed, or a flush-to-wall ceramic panel as a straight replacement for an old radiator.

• For visual impact and fast heat: 2,000W black Smart X aluminium convection heater, wall-mounted or floor-standing. Matt black and a slim profile sit comfortably alongside modern interiors and industrial-style renovations. 2,000W of convection will lift a 20 m² room several degrees within half an hour, which matters when the room has been shut all day.

• For a radiator replacement: 2,000W smart white ceramic-core wall heater. Fitted flush to the wall, it occupies less depth than a conventional panel radiator and frees the floor. The ceramic core gives the slow, even, radiant warmth people associate with water-filled radiators — without draining the boiler. This is the option for anyone replacing an old radiator in a room that has been extended, or in a flat where the communal boiler is expensive to run.

6. Rented Flats and Student Accommodation: No Drill, No Permission

Tenants in studios and en-suites cannot put holes in the wall, and they move every 9–12 months. That rules out nearly every wall-mounted heater on the market and leaves them buying £20 fan heaters that are noisy, expensive to run, and a fire risk.

Recommendation: 2,000W black Smart X convection heater on castors. The pitch is simple and specific: no drilling, no fixings, no damage to the deposit, plug in and go, and it comes with you when you move. Add a line about the flat-back design allowing an optional wall bracket later if the landlord agrees.

7. Hallways and Landings: the Coldest 6 m² in Britain

Victorian and Edwardian terraces — still a huge share of UK housing stock — have long entrance halls and tall stairwells that act as a chimney. Cold air pours in under the front door, rises up the stairs, and cools the whole house. It is the last place people think to heat, and often the first place they should.

Recommendation: 1,000W white ceramic-core wall heater, standard or smart. Low output is correct here: you are creating a warm curtain against draughts, not heating a room to 21°C. At just 9.4 cm deep it fits between door frames and above skirting without blocking a narrow hallway. Mount it opposite or adjacent to the front door, roughly 15–20 cm above the floor, so the rising warm air meets the incoming cold air at the point of entry.

How to Calculate What Size Electric Heater You Need

Choosing the right electric heater size in watts helps you heat a room efficiently without wasting energy. Whether you need an electric heater for a bedroom, home office, conservatory, garage or living room, this simple calculation can help you estimate the required wattage in just two minutes.

Calculate the room size in square metres (m²). Measure the length and width of the room, then multiply them together.

Allow 100W per m² for a well-insulated room. This is a useful starting point for rooms with cavity wall insulation, loft insulation and double glazing.

Allow 150–200W per m² for a poorly insulated room. You may need more heating power if the room has single glazing, two or more external walls, no cavity wall insulation, or is an unheated conservatory or outbuilding.

Choose the nearest suitable electric heater wattage, rounding up when necessary. A correctly sized heater operating under thermostat control can maintain your target temperature without running continuously at full power. An undersized heater may struggle to reach the desired temperature and run for longer.

Quick example: For a well-insulated 12 m² home office, a 1,200W electric heater is a reasonable starting estimate. For a poorly insulated 12 m² conservatory, you may need approximately 1,800–2,400W, depending on glazing, draughts and heat loss.

FAQs

What Size Heater Do I Need for a Conservatory?

Plan for 150–200W per m² because of the glazing. A 2,000W heater is the practical minimum for a typical 3 × 4 m conservatory and will keep it comfortable for evening use, but it will not make a large orangery habitable in midwinter.

Are Electric Heaters Expensive to Run in the UK?

Per unit of heat, electricity costs roughly three times as much as gas under the current price cap (26.32p versus 7.97p per kWh, Ofgem, 2026). They are cheaper overall when you are heating one room instead of a whole house — which is exactly the situation in a home office, a conservatory, or a shed.

Ceramic-core or Convection — Which Should I Choose?

Choose convection where you need fast heat in a large or glass-heavy space and will only use it intermittently. Choose ceramic-core where you want steady, silent, radiant warmth for hours at a time, especially in bedrooms, home offices and outbuildings.

Can I Fit a Wall-mounted Heater in a Rented Flat?

Only with your landlord's permission. If that is not available, a floor-standing convector on castors gives you the same output with no fixings and no deposit risk.

Will an Electric Heater Dry out the Air in My Bedroom?

Fan heaters and convection heaters move a lot of air and can feel drying. Ceramic-core panels rely more on radiant heat, so the air movement is gentler — which is why they are the usual recommendation for bedrooms and for anyone with respiratory sensitivity.

Do I Need an Electrician to Install One?

Wall-mounted models in this range are designed for a standard 13A plug-in supply rather than a dedicated circuit, so no consumer-unit work is normally required. Always follow the manufacturer's installation instructions and keep clearances from curtains and furniture.

The takeaway

Buy for the room, not for the house. A 1,000W ceramic panel in the hallway, a 1,500W smart unit in the study and a 2,000W convector that moves between the conservatory and the garage will heat the spaces you actually use for a fraction of what it costs to run a boiler through an empty house. Start with the room that annoys you most in winter — it is almost always the conservatory, the shed or the hallway.