Microwave vs Oven: 2026 UK Cost Comparison

A microwave uses a fraction of the power of a fan oven. Here's exactly how much you save by reheating in the microwave at 2026 UK prices.

Updated: May 2026 — Power Guardian UK Editorial Team

A fan oven sucks up serious electricity. A microwave doesn't. If you reheat or cook small portions in the oven, you're throwing away £40–£100 a year.

Cost per use at 27p/kWh

| Appliance | Power | Time | Energy | Cost per use | |---|---|---|---|---| | Microwave (800W) | 0.8 kW | 5 min | 0.07 kWh | 1.8p | | Microwave (800W) | 0.8 kW | 10 min | 0.13 kWh | 3.6p | | Fan oven (preheat + cook) | 2.0 kW | 30 min | 1.0 kWh | 27p | | Fan oven (1hr roast) | 2.0 kW | 60 min | 2.0 kWh | 54p | | Combi microwave/oven | 1.4 kW | 20 min | 0.47 kWh | 12.6p |

The headline number

A microwave uses about 1/15th of the energy of a fan oven for reheating a single portion. Use it for leftovers, ready meals, jacket potatoes (start in microwave, finish in oven for crisp skin) and steaming veg.

When the oven still wins

- Cooking 4+ portions at once — efficiency per person improves - Roasts, baking, anything needing browning - Batch cooking on a Sunday for the week

Quick-win swaps

- Reheating one plate: microwave, not oven - Jacket potato: microwave 8 min, oven 10 min (vs 75 min oven only) — saves 21p per spud - Frozen pizza for one: air fryer or grill, not full oven - Steaming veg: microwave with 2 tbsp water, lidded — uses 1.5p of energy

What this saves a typical UK home