Shower vs Bath Calculator
Enter your shower minutes, the head's litres per minute, washes per week and your energy price. The calculator totals water and heating cost for showers versus a standard 80-litre bath - and finds the exact minute your shower becomes a bath.
Water-company pages count litres and stop; the bigger half of the bill is heating them. This calculator prices both halves, exposes the ten-minute crossover, and lets the bath keep its honest place as a priced luxury.
How to use
- Time a real shower once - estimates run short by minutes.
- Check flow: hold a jug under the head for ten seconds and multiply, or use the 8 L/min default for a modern head.
- Enter washes per week and your energy price; read both weekly bills and the crossover minutes.
Frequently asked questions
Is a shower always cheaper than a bath?
Only under ten minutes at 8 litres a minute: past 80 litres, a long power shower is a bath with standing. The average seven-minute shower uses about half a bath's water - the crossover, not the label, decides the bill.
What does a bath cost in water and energy?
80 litres heated 35 degrees over mains temperature is about 3.3 kWh plus the water itself - at typical prices, roughly the cost of a nine-minute shower. The energy share is four times the water share, which is the part most comparisons skip.
Do low-flow showerheads really help?
Yes - 8 down to 6 litres a minute saves a quarter of water and heating with little felt difference on a modern head. Weeks to payback, and it shortens every shower's litres without a timer or an argument.
How much does a 10-minute shower cost?
At 8 L/min and typical energy prices, about 80 litres and 3.3 kWh heated - the same water as a bath. Five minutes at 6 L/min cuts both by half; the cheapest shower is short, cool-ish and low-flow.