DeviceWattsHours/dayDuty %Qty
Daily£0.72
Monthly£22.03
Annual£264.351012 kWh
How the calculation works
For each row: watts × hours per day × duty cycle × quantity. The calculator divides by 1,000 to convert to kilowatt-hours, totals the rows, then applies your pence-per-kWh rate. Standing charges are excluded because you pay them regardless of the aquarium.
Use duty cycle carefully
A 150W heater does not normally draw 150W all day. Its actual duty cycle changes with room temperature, set point, tank volume and heat loss. Start with an estimate, then improve it with a plug-in energy monitor. Dimmable lights and variable pumps may also draw less than their label maximum.
Source and related planning
The default electricity rate comes from Ofgem’s current unit-rate table. Use the setup budget calculator for purchase costs, or read the UK setup-cost guide before choosing a system.