Know the units
Watts, kilowatt-hours and BTU for Saudi homes
The three units that prevent most appliance and air-conditioner comparison mistakes.
Watts are instantaneous power
A 1,500-watt appliance draws power at that rate while operating. Watts alone do not reveal monthly consumption; operating time and duty cycle still matter.
Kilowatt-hours are billed energy
Divide watts by 1,000, multiply by operating hours, then apply the tariff. A 1,500 W heater used for two hours consumes 3 kWh.
BTU/h is cooling output
An AC’s BTU/h rating describes cooling capacity, not its electrical draw. Use electrical input watts or verified annual kWh when estimating cost.
Power, energy and time
Power describes a rate; energy accumulates that rate over time. The basic relationship is kWh = watts ÷ 1,000 × hours. If equipment cycles, multiply by a measured or defensible duty factor. Keeping every unit visible is the simplest protection against errors of 1,000 or confusing a monthly figure with an hourly one.
Input and output are different
Labels may show electrical input, heating output, cooling capacity, battery capacity and annual energy on the same product. These numbers answer different questions. Use electrical input or measured energy for cost, cooling output for room capacity, and usable battery energy for runtime.
A comparison example
A 100 W device used for ten hours consumes the same 1 kWh as a 1,000 W device used for one hour. The higher-power device is not automatically the larger monthly cost; schedule, quantity and cycling determine total energy. Compare complete usage patterns rather than nameplate watts alone.
Measure safely
A correctly rated plug-in energy monitor can improve estimates for compatible appliances. Never open electrical panels, improvise adapters or measure fixed wiring without the proper competence and equipment. For air conditioners, water heaters and other fixed loads, use label data or a qualified electrician.
Related guides
Estimate an air-conditioner’s monthly electricity cost
A transparent alternative to converting cooling capacity directly into electricity cost.
Inverter or fixed-speed AC without exaggerated claims
Compare purchase premium, verified consumption and simple payback using your own pattern.
What changes a room AC capacity estimate?
Room area is only the beginning; exposure, insulation, height and people change the result.
Primary sources
Last source check: 2026-07-29