Electrical & HVAC load calculator
Size the electrical connected load and air-conditioning cooling load for any building from its built-up area and use type — instantly, with transparent coefficients you can see and adjust. Indicative figures for early-stage budgeting.
Estimated loads
for —
Electrical — demand load
0 kW
Connected: 0 kW
HVAC — cooling load
0 tons
≈ 0 kW thermal
Electrical intensity used: —.
Indicative only. These figures use rule-of-thumb coefficients for early-stage budgeting and feasibility. Always have a qualified MEP engineer run a detailed load calculation to local codes before sizing equipment, cables or switchgear.
The coefficients we use
Nothing is hidden. The electrical load is built up from watts per square foot; the cooling load from square feet per ton of refrigeration. Both vary by building use type.
| Use type | Electrical (W/sqft) | HVAC (sqft / ton) |
|---|---|---|
| Residential | 3 | 600 |
| Office / commercial | 5 | 350 |
| Retail / showroom | 6 | 300 |
| Hotel / hospitality | 6 | 325 |
| Hospital / clinic | 8 | 250 |
| School / institutional | 4 | 350 |
| Warehouse / industrial | 2 | 800 |
| Data centre / server room | 40 | 80 |
Conversions: 1 ton of refrigeration = 3.517 kW thermal · 1 m² = 10.764 sqft. Demand load = connected load × diversity factor × (1 + future margin); cooling tons include the future margin.
About this calculator
- How is the electrical load estimated?
- We multiply the built-up area by a connected-load coefficient in watts per square foot that depends on the building use type (for example ~5 W/sqft for offices, ~3 W/sqft for homes). A diversity / demand factor is then applied to estimate the realistic demand load, and an optional future margin adds spare capacity. These are early-stage rules of thumb, not a substitute for a circuit-by-circuit load schedule.
- How is the HVAC cooling load (tons) calculated?
- Cooling load uses a square-feet-per-ton coefficient by use type (for example ~350 sqft/ton for offices, ~600 sqft/ton for homes). Tons of refrigeration are converted to kW at 1 ton = 3.517 kW. This is a sizing shortcut for budgeting and feasibility — a proper heat-load (block-load) calculation accounts for orientation, glazing, occupancy, ventilation and climate.
- Are these numbers accurate enough to design from?
- No. They are indicative figures for early-stage budgeting, feasibility and sanity-checking a contractor's numbers. Always have a qualified MEP engineer run a detailed load calculation to local codes before sizing equipment, cables or switchgear.
- Does it work in metric and imperial units?
- Yes. You can enter the area in square feet or square metres and the calculator converts automatically. United Kingdom defaults to square metres, and you can switch any time.