Convector heaters and oil-filled radiators both run on electricity and cost the same per hour at the same wattage — but they feel completely different to live with. Convectors blast hot air into a room in under three minutes. Oil-filled radiators take 10–15 minutes to warm up, then keep the room warm for 20–30 minutes after you switch them off.
Which is right for your home depends on how long you need heat, how large the room is, and whether you have children or pets. This guide covers both types in full — with specific product picks and 2026 UK running cost figures.
Quick Verdict
| If you need... | Choose... |
|---|---|
| Fast heat in under 5 minutes | Convector heater |
| Steady warmth over 2+ hours | Oil-filled radiator |
| Bedroom or nursery (safety priority) | Oil-filled radiator |
| Home office (on for 1–2 hours at a time) | Convector heater |
| Lowest long-term running cost | Oil-filled radiator (heat retention means fewer on-cycles) |
| Lightweight and portable | Convector heater |
How Each Type Works
Convector Heaters
A convector heater draws cold air in from the bottom through a metal heating element, then releases hot air from the top. This creates a convection current that circulates warm air around the room. The process is immediate — within two to three minutes, you feel the heat. When you switch it off, the room cools down at the same speed.
Oil-Filled Radiators
An oil-filled radiator heats a sealed reservoir of diathermic oil using an electric element. The oil transfers heat through the metal fins to the surrounding air — slowly at first, then at a steady rate once up to temperature. That 10–15 minute warm-up time is the trade-off for one major advantage: the oil retains heat after the element switches off, keeping the room warm without drawing power.
Running Costs — What You Actually Pay
Both heater types consume the same electricity at the same wattage. At the UK Ofgem price cap rate of 27.69p per kWh (January 2026), running costs are:
| Wattage | Cost per hour | Cost per 8 hours | Suitable room size |
|---|---|---|---|
| 1,000W (1kW) | 27.7p | £2.22 | Up to 10m² |
| 1,500W (1.5kW) | 41.5p | £3.32 | 10–15m² |
| 2,000W (2kW) | 55.4p | £4.43 | 15–20m² |
| 2,500W (2.5kW) | 69.2p | £5.54 | 20–25m² |
| 3,000W (3kW) | 83.1p | £6.65 | 25–30m² |
Where oil-filled radiators have the running cost edge: because the oil retains heat, a thermostatically controlled oil-filled radiator cycles on and off to maintain temperature — typically running the element for 40–60% of the time. A convector heater on the same thermostat runs more frequently because the room cools faster when it's off. Over a full day, an oil-filled radiator in a well-insulated room typically costs 15–25% less to run than a convector at the same wattage.
Our Top Convector Heater Picks
Convector heaters are best for rooms you use in short bursts: a home office during working hours, a bathroom in the morning, or a spare bedroom when guests stay. Look for models with a thermostat and tip-over protection as standard.
Best Overall: Dimplex 2kW Convector Heater
2,000W · thermostat · tip-over cut-out · UK's most trusted heating brand
Dimplex is the UK's largest heating manufacturer and their convectors are a staple of British homes. This 2kW model heats a medium room (up to 20m²) in under five minutes, has a simple rotary thermostat, and includes tip-over and overheat protection. Solid, no-fuss, and built to last.
Best Budget: 1kW Convector Heater with Thermostat
1,000W · thermostat · under £30 · ideal for small rooms up to 10m²
If you are heating a bedroom, home office, or single room under 10m², a 1kW convector is all you need and costs just 27.7p per hour to run. Pick any reputable brand with a thermostat and overheat protection — spend the savings on something else.
Our Top Oil-Filled Radiator Picks
Oil-filled radiators suit rooms you spend extended time in: living rooms, bedrooms used for reading or working, and conservatories. The thermostat and heat retention make them significantly more efficient for sustained use than convectors.
Best Overall: De'Longhi Dragon 4 Oil-Filled Radiator
1,500W · 11-fin · 3 heat settings · thermostat · the UK benchmark
The De'Longhi Dragon series has been the best-selling oil-filled radiator in the UK for years, and the Dragon 4 improves on its predecessor with a higher BTU output per fin and a more precise thermostat. The 1,500W / 11-fin configuration suits rooms up to 15m². It runs quietly, heats evenly, and the fins are protected by a guard that stays cool enough to be safe around children.
Best for Large Rooms: 2.5kW Oil-Filled Radiator
2,500W · 13-fin · for rooms 20–25m² · thermostat essential
For living rooms and open-plan spaces over 20m², you need at least 2.5kW of output. Look for a model with a digital thermostat rather than a rotary dial — the more precisely it holds temperature, the less it cycles and the lower your bill. De'Longhi, Dimplex, and Warmlite all produce reliable 2.5kW models at this end of the market.
Best Budget Oil-Filled: 1.5kW Under £50
1,500W · 9-fin · thermostat · suits bedrooms and home offices up to 15m²
You do not need to spend over £100 to get a solid oil-filled radiator. Several reliable 1.5kW models with thermostat and safety cut-out are available under £50 on Amazon. Look for at least 9 fins, a genuine thermostat (not just a timer), and tip-over protection. Avoid unbranded units without UK safety certification.
Safety — Which Is Safer Around Children and Pets?
Oil-filled radiators are the safer option when children or pets are present. The outer fins of a quality oil-filled radiator reach around 60–80°C — hot enough to cause discomfort on contact but rarely a burn risk with a protective guard fitted. The guard itself stays significantly cooler.
Convector heaters have a heating element exposed to the airflow. The element itself reaches temperatures above 200°C, and while it is enclosed, the air outlet can reach 80–90°C. Placing a toy or clothing against a convector vent is a fire risk. Keep both types away from curtains, furniture, and soft furnishings, but exercise more caution with convectors if you have young children.
Convector Heater vs Oil-Filled Radiator: Full Comparison
| Convector Heater | Oil-Filled Radiator | |
|---|---|---|
| Warm-up time | 2–3 minutes | 10–15 minutes |
| Heat retention after switch-off | None — cools immediately | 20–30 minutes of residual heat |
| Running cost (equal wattage) | Same per hour | 15–25% lower over a full day |
| Weight | Light (2–4kg) | Heavy (7–15kg) |
| Noise | Slight air movement | Near-silent |
| Safety around children | Caution needed | Safer option |
| Best use case | Short sessions, quick heat | Sustained warmth, bedrooms |
| Typical price range (UK) | £20–£80 | £35–£150 |
Frequently Asked Questions
Are oil-filled radiators cheaper to run than convector heaters?
At the same wattage, both cost the same per hour. However, oil-filled radiators are cheaper to run over a full day because the oil retains heat after the element switches off. If you leave either type running with a thermostat, the oil-filled model will cycle on less frequently, reducing total electricity consumed by roughly 15–25% in a well-insulated room.
How long does an oil-filled radiator take to heat up?
Most 1,500W oil-filled radiators reach operating temperature in 10–15 minutes from cold. Larger 2,500W models warm up slightly faster due to higher wattage. The room itself will feel noticeably warmer within 20–25 minutes of switching on.
Can I leave an oil-filled radiator on overnight?
Yes — oil-filled radiators with a thermostat and overheat protection are designed for extended use, including overnight. They are significantly safer than convector heaters for overnight operation because they have no exposed element and cycle on and off automatically to maintain temperature. Set the thermostat to 16–18°C for a bedroom overnight.
Are convector heaters bad for your health?
Convector heaters dry the air slightly more than oil-filled radiators because they heat and circulate air at higher temperatures. This can aggravate dry skin, eyes, or respiratory conditions in sensitive individuals. Oil-filled radiators heat the air more gently and are often the better choice if you spend long periods in the heated room.
Which is better for a bedroom?
An oil-filled radiator is better for a bedroom. It operates near-silently, retains heat after switching off (so it does not need to run all night), and is safer if children or pets sleep in the room. Set it with a thermostat at 16–18°C for an adult bedroom or 18–20°C for a child's room.
Do oil-filled radiators use less electricity than convectors?
Not per hour at the same wattage — both use the same electricity for the time they are on. The difference is that oil-filled radiators spend less time with the element running (because the oil holds heat between cycles). Over a 24-hour period on a thermostat, an oil-filled radiator typically runs its element for fewer total hours than a convector maintaining the same room temperature.
Which Should You Buy?
Buy a convector heater if you need to heat a room quickly for short periods (under two hours), you move the heater between rooms frequently, or budget is a primary concern — quality convectors cost less upfront.
Buy an oil-filled radiator if you heat a room for two or more hours at a time, you want quieter operation, you have children or pets, or you are leaving it running on a thermostat for extended periods. The higher upfront cost is recovered in running cost savings within one heating season.
For most UK households, the oil-filled radiator is the better long-term investment. For portable, occasional, quick-heat use, the convector is the more practical choice.
Contents
- 1 Quick Verdict
- 2 How Each Type Works
- 3 Running Costs — What You Actually Pay
- 4 Our Top Convector Heater Picks
- 5 Our Top Oil-Filled Radiator Picks
- 6 Safety — Which Is Safer Around Children and Pets?
- 7 Convector Heater vs Oil-Filled Radiator: Full Comparison
- 8 Frequently Asked Questions
- 8.1 Are oil-filled radiators cheaper to run than convector heaters?
- 8.2 How long does an oil-filled radiator take to heat up?
- 8.3 Can I leave an oil-filled radiator on overnight?
- 8.4 Are convector heaters bad for your health?
- 8.5 Which is better for a bedroom?
- 8.6 Do oil-filled radiators use less electricity than convectors?
- 9 Which Should You Buy?
