This calculator estimates daily, monthly, and annual fuel costs for running a generator in Pakistan. Enter the generator's kVA capacity, fuel type, average load percentage, hours of daily operation, and current fuel price to see itemised cost estimates.
Estimate Generator Fuel Cost
How generator fuel consumption actually scales
The relationship between generator size, load, and fuel consumption is non-linear. A 5 kVA generator at 100% load doesn't consume twice as much fuel as the same generator at 50% load — the consumption curve is roughly: at idle (no load) the engine burns 40–50% of its full-load fuel rate; at 50% load it burns about 70%; at 100% it burns 100%. Running a 10 kVA generator on a 3 kVA load wastes fuel — the engine has to maintain idle plus the load, but the idle component is large relative to the actual work. Right-sizing the generator for typical load matters more than picking the lowest-fuel-consumption model.
The calculator applies these load-based consumption curves automatically. For diesel: 0.20 L/kWh at 100% load, scaling up to 0.35 L/kWh at 25% load. For petrol: typically 0.30 L/kWh at 100% load, up to 0.50 L/kWh at light loads. For LPG: roughly 0.45 kg/kWh at full load. These are typical values for modern generators in reasonable condition; older or poorly-maintained generators run higher.
Choosing between fuel types — beyond just running cost
Fuel choice in Pakistani conditions involves more than per-litre comparison. Diesel generators run quietly at moderate loads, last longer (15–20 years for quality models), and use a fuel that's broadly available. The diesel itself is currently price-volatile due to international markets and government tax policy. Petrol generators are cheaper upfront, simpler mechanically, but consume noticeably more fuel per kWh and have shorter useful lifespans (8–12 years). LPG generators run cleanest with the least carbon residue, but LPG supply requires either large cylinder management at the home or a piped gas connection (gas grid is increasingly load-managed in winter, complicating reliability).
For most Pakistani households running a generator 2–4 hours daily, diesel is the standard choice. Lower-usage households (1 hour a day or less) often find petrol acceptable because the upfront savings outweigh the marginally higher fuel cost. Heavy-usage situations (commercial, 8+ hours daily) usually justify diesel's longer lifespan and lower per-hour fuel cost.
Calculator methodology and what it doesn't include
The estimate accounts for fuel consumption only — diesel/petrol/gas at the current price you enter, scaled by the actual generator load and operating hours. It does not include oil consumption (which adds a small ongoing cost), routine servicing (typically Rs. 5,000–10,000 per year for a residential generator), or eventual major repairs or replacement. A complete cost of generator ownership over 10 years usually breaks down as roughly 70% fuel, 15% servicing and repairs, and 15% capital cost amortisation. The calculator captures the largest component cleanly.
For a complete cost comparison against alternatives — solar plus battery, larger UPS systems, grid backup arrangements — combine this calculator's annual fuel cost estimate with the maintenance and capital cost figures above. Solar plus battery systems typically have higher upfront capital but much lower running cost; the payback period against generators depends on outage frequency and electricity availability.
Generator-fuel questions Pakistani owners typically have
Petrol versus diesel versus gas generators — which is cheapest to run in Pakistan?
For typical Pakistani residential use, the running-cost order from cheapest to most expensive is usually: gas (CNG/LPG) < diesel < petrol. A 5 kVA diesel generator at 60% load consumes about 0.9 to 1.1 litres per hour; at Rs. 280 per litre diesel, that's Rs. 250–310 per hour. The same capacity in petrol consumes 1.2–1.4 litres per hour at Rs. 290 per litre, so Rs. 350–410 per hour — meaningfully more expensive. LPG generators consume 1.5–2.0 kg per hour at around Rs. 220 per kg, so Rs. 330–440 per hour — close to petrol. The upfront cost order reverses — petrol generators are cheapest to buy, diesel mid-range, gas most expensive — so total cost of ownership depends heavily on usage hours per year.
How do I figure out what kVA generator size my Pakistani home actually needs?
Add up the wattage of everything you want to run simultaneously during an outage, then convert to kVA by dividing by the power factor (typically 0.8 for mixed residential loads). A household running 5 ceiling fans (300W), 10 lights (100W), TV (150W), internet router (15W), refrigerator (200W average), and one 1.5-ton AC (1,800W) totals 2,565W. Divided by 0.8, that's 3.2 kVA — so a 5 kVA generator gives reasonable headroom for startup surges and additional small loads. Avoid going below 4 kVA for typical 3–4 bedroom homes; smaller generators trip frequently when ACs or fridges cycle on. Avoid going above 7 kVA unless you're running multiple ACs and major appliances together — oversized generators run inefficiently at light loads and consume disproportionate fuel.
Why does my generator burn more fuel per hour than the manufacturer's specs promised?
Three usual causes. First, manufacturer specs are usually quoted at a specific load (often 50% or 75%); running at higher load increases fuel consumption proportionally. Second, generator efficiency degrades with age — carbon buildup on internal components, worn injectors in diesel engines, slightly off-spec spark timing in petrol engines all reduce efficiency by 10–25% over the first few years. Third, the manufacturer's test conditions assume ideal ambient temperature; Pakistani summer heat (above 35°C) reduces generator efficiency noticeably. Regular servicing — oil changes every 100 operating hours, air filter cleaning, spark plug replacement annually — typically recovers most of the lost efficiency. A poorly-maintained 5-year-old generator can consume 30–40% more fuel than its original spec for the same output.
Auto-start versus manual-start generators — is the convenience worth the extra cost?
Auto-start generators add Rs. 30,000–60,000 to the purchase price and include an Automatic Transfer Switch (ATS) that detects grid failure and starts the generator within 10–30 seconds. The convenience is real — you don't need to be home to maintain power during outages, sensitive electronics don't experience extended outage gaps, and household routines continue uninterrupted. For households with frequent unpredictable outages, auto-start pays back in convenience within a year. For households with predictable load-shedding schedules where someone is always around to start the generator, manual-start is fine. Auto-start systems also typically include better engine protection (low-oil shutdown, over-temperature shutdown) which extends engine life independently of the convenience benefit.
How often should I service a home generator, and what does basic servicing cost in Pakistan?
Standard servicing intervals: oil change every 100 operating hours (or annually if usage is lighter), air filter cleaning every 50 hours and replacement every 200 hours, spark plug replacement every 100 hours for petrol engines, fuel filter replacement annually for diesel, and full inspection every 500 hours or annually. Basic servicing (oil change, filters, spark plug, inspection) costs Rs. 3,000–6,000 at a generator service centre, plus parts. Diesel generators are typically more expensive to service due to injector cleaning and fuel system maintenance. Skipping servicing is the single largest cause of generator failure and inefficiency — a Rs. 50,000 generator that fails at year three because of neglected servicing is much more expensive than a Rs. 5,000 annual service bill that keeps it running for ten years.