BaytMeterمقياس البيت

Formula version 0.1 · checked 29 July 2026

Every result should be explainable.

BaytMeter uses full precision internally and rounds only for display. It rejects negative and non-finite inputs instead of silently changing them. Regulatory inputs live in one versioned configuration file so a verified tariff change can update every calculator consistently.

Independent estimate. BaytMeter is not affiliated with Saudi Electricity, SERA, SEEC, SASO, ZATCA or another government body. Results are for planning and education—not an official bill, product certification or professional engineering calculation.

Residential bill

The energy charge applies SAR 0.18/kWh to the first 6,000 kWh and SAR 0.30/kWh only to consumption above that point. A selected meter-service fee is added before optional VAT. Previous balances, credits, fixed-bill reconciliation and account adjustments are excluded.

energy charge = 0.18 × min(kWh, 6000) + 0.30 × max(kWh − 6000, 0) estimated total = (energy charge + selected meter fee) × 1.15

Appliance and AC running cost

Electrical input—not cooling capacity—is multiplied by operating time. AC cost also applies an adjustable average duty cycle because a compressor does not necessarily remain at rated input continuously.

kWh = watts ÷ 1000 × hours/day × days × duty factor cost = kWh × selected SAR/kWh rate

Near the 6,000 kWh threshold, a future baseline mode will calculate the difference between the whole bill before and after adding a device. Until then, select the applicable marginal rate and test a range.

Room AC capacity screening

The estimator begins with a published area-to-capacity screening table, then applies visible height, Saudi heat-exposure, sunlight, insulation and occupancy assumptions. It rounds up to a commonly marketed capacity. This is not an ASHRAE load calculation and should not be used for code compliance or unusual open-plan, high-glazing or central-system designs.

screening BTU/h = area-table capacity × height factor × heat factor × sunlight factor × insulation factor + 600 × occupants above two

Inverter comparison

The current scenario tool compares a conventional estimate with a user-entered reduction and purchase premium. The percentage is never presented as a guaranteed product saving. Model-specific annual label consumption is preferred when available.

annual saving = conventional annual cost − inverter scenario cost simple payback years = extra installed price ÷ annual saving

Power-station runtime

Runtime uses rated watt-hours multiplied by a user-entered usable-capacity percentage, then divides by continuous load. It does not yet validate inverter continuous or surge ratings; those must be checked on the manufacturer specification.

runtime hours = rated Wh × usable percentage ÷ continuous load W

Standby savings

The calculation subtracts controller consumption from the power actually cut, so a smart plug cannot claim savings larger than the avoided standby draw.

net saved W/device = max(standby W × reduction − controller W, 0) annual kWh = net saved W × quantity × idle hours/day × 365.25 ÷ 1000

Ownership cost

The preview combines purchase price, estimated electricity, annual maintenance and resale value. A later comparison mode will add delivery, installation, consumables and verified rebates as separate visible inputs.

ownership cost = purchase + period energy + period maintenance − resale value

Primary sources