There is no general answer to this, which is why it gets argued about. A short shower off a gas combi is much cheaper than a bath; a long shower off an electric shower unit is usually more expensive than one. The only thing that settles it is your own numbers, so here they are.
Bath or shower: which is cheaper in your house?
Change anything. The defaults are a typical UK bath, a typical mixer shower flow rate, and the current price cap averages.
What the answer usually turns out to be
- Gas combi, short shower: the shower wins comfortably. At 10 litres a minute, a bath is roughly equivalent to an eight minute shower, so anything shorter is cheaper.
- Power shower: flow rates of 15 litres a minute and above close the gap fast. A ten minute power shower uses more hot water than a bath.
- Electric shower unit: it heats water on demand with electricity at roughly three times the price of gas per kWh, but it only heats what you use. Against a gas-heated bath it is usually more expensive; against an immersion-heated one it is usually cheaper.
- The cheapest change available is a minute less in the shower, which costs nothing and applies every single day.
Rates from Ofgem, read 15 September 2026. Heat calculation uses the specific heat capacity of water and an assumed 35 degree rise from mains temperature, with gas divided by an assumed 85 per cent boiler efficiency. Your incoming mains temperature, your boiler and your shower all differ, which is why every field above is editable.
Energy figures are worked from the Ofgem price cap on the date shown and from typical power for the appliance class, not from a named model. Your own rate and your own rating plate are the ones that count. Full disclaimer.