Bar shows the shower cost as a share of the bath cost (full bar = same cost or more). Energy uses 1.162 Wh to warm 1 litre of water by 1 °C.
Formula and breakdown
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This bath vs shower cost calculator compares the full cost of one bath with one shower, energy and metered water together, for households in the UK and Ireland with a gas boiler, an electric immersion or an electric shower. It also works out the break-even shower length, the point at which your shower starts to cost more than your bath, and the yearly difference for your household.
Quick answer: A bath vs shower cost calculator adds the energy to warm the water to the water and sewerage charge. An 80 litre bath heated by gas at October 2026 prices costs about 60p on a Thames Water meter; an 8 minute mixer shower at 9 litres a minute costs about 54p. The shower stays cheaper up to about 9 minutes.
What Is a Bath vs Shower Cost Calculator?
A bath vs shower cost calculator is a tool that prices a bath and a shower on the same basis, so you can see which is cheaper for your bathroom and tariff. In plain words: litres used times the temperature rise times 1.1622 Wh gives the heat needed; divide by the water heater’s efficiency and multiply by the fuel price for the energy cost; then add litres times your water and sewerage price.
The 1.1622 Wh figure is the energy to warm one litre of water by 1 °C. It comes from the specific heat capacity of liquid water, about 4,184 J per kg per kelvin at 20 °C according to the Wikipedia article on specific heat capacity, divided by 3,600 seconds in an hour. One litre of water weighs about 1 kg. It does not matter that hot water leaves the cylinder or boiler at 60 °C and is mixed with cold: the energy needed is set by the final temperature of the water you use.
How Do You Use the Bath vs Shower Cost Calculator?
- Choose your shower type: a mixer or combi shower takes hot water from the boiler or cylinder; an electric shower heats cold mains water itself.
- Enter how much water you put in the bath. 80 litres is an example; fill a bucket of known size to measure yours.
- Enter your shower length, and either the flow rate for a mixer shower or the kW rating for an electric shower.
- Set the bath and shower temperatures and the cold inlet temperature, which is colder in winter.
- Choose how the bath water is heated, check the efficiency and prices, and enter your water and sewerage price per m³, or 0 if you pay an unmetered charge.
- Read which option is cheaper per wash, the break-even shower length and the yearly difference.
Is It Cheaper to Have a Bath or a Shower?
A shower is cheaper than a bath only while it uses less hot water than the bath, so the answer depends on flow rate and minutes: at 9 litres a minute an 80 litre bath and a shower cost the same at about 9 minutes. A power shower at 15 litres a minute reaches the same cost in just over 5 minutes, while a low flow head at 6 litres a minute lasts over 13 minutes.
The table shows break-even shower lengths from the bath vs shower cost calculator for gas-heated hot water at 85% efficiency, a 30 °C temperature rise, the October 2026 cap gas price and metered water at £4.2067 per m³. Electric shower rows use the shower’s own kW rating and the cap electricity price.
| Shower | Cost per minute | Break-even vs 60 L bath | vs 80 L bath | vs 100 L bath | vs 150 L bath |
|---|---|---|---|---|---|
| Mixer, 6 L/min (low flow) | 4.5p | 10.0 min | 13.3 min | 16.7 min | 25.0 min |
| Mixer, 9 L/min | 6.7p | 6.7 min | 8.9 min | 11.1 min | 16.7 min |
| Mixer, 12 L/min | 9.0p | 5.0 min | 6.7 min | 8.3 min | 12.5 min |
| Power shower, 15 L/min | 11.2p | 4.0 min | 5.3 min | 6.7 min | 10.0 min |
| Electric, 8.5 kW (4.1 L/min) | 5.4p | 8.2 min | 11.0 min | 13.7 min | 20.6 min |
| Electric, 9.5 kW (4.5 L/min) | 6.1p | 7.4 min | 9.8 min | 12.3 min | 18.5 min |
| Electric, 10.5 kW (5.0 L/min) | 6.7p | 6.7 min | 8.9 min | 11.1 min | 16.7 min |
The bath costs in this table are 44.9p for 60 litres, 59.8p for 80 litres, 74.8p for 100 litres and £1.12 for 150 litres. Flow rates and bath volumes are example values: measure your own for a reliable answer.
How Much Does Water Cost Compared With the Energy to Heat It?
On a water meter, the water and sewerage charge is often the larger part of a gas-heated bath or shower: at Thames Water’s 2026/27 metered rates each litre costs about 0.42p, while heating it by 30 °C with gas costs about 0.33p. That is why short showers save money even in homes with cheap gas.
Thames Water’s metered charges from 1 April 2026 are £2.7346 per m³ for clean water and £1.4721 per m³ for wastewater, £4.2067 per m³ together. They are the example default in the bath vs shower cost calculator; charges vary by water company, so take yours from your bill. If you pay a fixed rate based on rateable value, enter 0, because extra litres then cost you nothing in water charges and only the energy matters.
Is an Electric Shower Cheaper Than a Bath?
An electric shower is cheaper than an 80 litre gas-heated bath up to about 10 minutes for a 9.5 kW unit, even though electricity costs 26.32p per kWh against 7.97p for gas. The reason is flow: a 9.5 kW shower can only heat about 4.5 litres a minute by 30 °C, so it uses far less water than a mixer shower.
An electric shower turns almost all its electricity into heat in the water, as described in the Wikipedia article on electric heating, so the calculator treats it as 100% efficient. Choose the electric shower option in the bath vs shower cost calculator and enter the kW on the unit’s label. In winter the inlet water is colder, flow drops and the same shower costs the same per minute but delivers less water. For more detail by kW rating, use our electric shower running cost calculator.
How Much Does a Bath Cost With an Electric Immersion Heater?
Heating bath water with an electric immersion heater at the October 2026 cap price of 26.32p per kWh costs nearly three times as much in energy as gas: an 80 litre bath at a 30 °C rise needs about 2.79 kWh, roughly £1.07 including metered water. Choose the electric option in the bath vs shower cost calculator and the efficiency changes to 100%; lower it to allow for cylinder standing losses if you know them.
Off-peak electricity changes the picture, because an immersion heater on an Economy 7 or similar tariff heats the cylinder at the night rate. Enter your off-peak rate as the electricity price to test it. Our immersion heater running cost calculator covers heating a whole cylinder, the watts to kWh calculator converts element power and hours into energy, and the electricity cost calculator prices any other appliance on the same tariff.
Worked Example: Family of Four Choosing Between Baths and Showers
Example: a household in Reading with a gas combi boiler and a Thames Water meter is comparing an 80 litre bath at 40 °C with an 8 minute mixer shower at 9 litres a minute, cold water at 10 °C and boiler efficiency of 85%.
- Bath heat: 80 x 1.1622 Wh x 30 °C = 2.79 kWh. Gas: 2.79 / 0.85 = 3.28 kWh x 7.97p = 26.2p.
- Bath water: 80 L x 0.42067p = 33.7p. Bath total: 59.8p.
- Shower water: 9 x 8 = 72 L. Heat 2.51 kWh, gas 2.95 kWh x 7.97p = 23.5p. Water 72 x 0.42067p = 30.3p. Shower total: 53.8p.
- Shower cost per minute: 53.8p / 8 = 6.7p. Break-even: 59.8p / 6.7p = 8.9 minutes.
- One wash a day each, four people: 28 washes a week. Showering instead of bathing saves (59.8p minus 53.8p) x 28 x 52 = about £87 a year.
Cutting each shower to 5 minutes in this example brings it to 33.6p, a saving of about £381 a year against daily baths for four people. The bath vs shower cost calculator shows the same result when you change the minutes.
Frequently Asked Questions
How much does a bath cost in the UK?
An 80 litre bath at 40 °C with a 10 °C cold supply needs about 2.8 kWh of heat. From a gas boiler at 85% efficiency and the October 2026 cap price that is about 26p of gas, plus about 34p of water and sewerage on a Thames Water meter: about 60p in total.
How many minutes of shower equals a bath?
Divide the bath volume by the shower flow rate when both are at similar temperatures. An 80 litre bath equals about 9 minutes at 9 litres a minute, about 5 minutes for a 15 litre a minute power shower and about 10 minutes for a 9.5 kW electric shower.
Does a shower use less water than a bath?
Only if it is short enough. A mixer shower at 9 litres a minute uses 72 litres in 8 minutes, less than an 80 litre bath, but 108 litres in 12 minutes. Electric showers use less because their heater limits the flow, often to around 4 to 5 litres a minute.
Is it cheaper to have a bath if I am not on a water meter?
Without a meter, extra water costs nothing per litre, so only the heating energy counts and the gap narrows. Enter 0 for the water price. A gas-heated 80 litre bath then costs about 26p and an 8 minute, 9 litre a minute shower about 24p.
Why is the cold water temperature an input?
The energy needed rises with the gap between the cold supply and the temperature you use. Mains water is colder in winter, so a bath or mixer shower costs more, and an electric shower delivers less flow at the same kW. 10 °C is an example value.
Does this bath vs shower cost calculator include standing charges?
No. Gas, electricity and water standing charges are paid regardless of whether you bath or shower, so they do not change the comparison. The calculator only counts the energy and metered water each wash uses.
Checked October 2026 by the Solaxyra Editorial Team. Sources: Ofgem: Energy price cap 1 October to 31 December 2026, Thames Water: Metered charges 2026/27, Wikipedia: Specific heat capacity, Wikipedia: Electric heating.