Diesel GensetFuel Consumption Calculator

The calculator uses the ISO 8528 Specific Fuel Consumption (SFC) method. You enter your genset rating (kVA), brand, average load percent, hours per day, days per month, and your local diesel pump price. The engine interpolates the SFC curve (g/kWh) for your brand at the chosen load point, multiplies by the effective electrical output (kW = kVA × load × 0.8 power factor), and divides by HSD diesel density (0.832 kg/L) to get litres per running hour. Multiplied across hours and days, you get monthly + yearly fuel litres, INR cost with a confidence band, CO2 footprint (DEFRA factor 2.68 kg/L), and the cost-per-kWh delivered for direct comparison with grid power.

Nine brand profiles: Greaves Cotton, Kirloskar Oil Engines, Cummins India, Mahindra Powerol, Ashok Leyland, Eicher (VECV), Caterpillar, Perkins, plus a generic CPCB IV+ option for any brand we haven't named, and a generic CPCB II/III curve for older pre-2024 sets. Greaves SFC is verified from the official CPCB IV+ technical brochure on file. Other brands use industry-typical CPCB IV+ values within +/-5% tolerance, which we mark prominently with an 'Approx' badge. We're brand-agnostic on purpose - even if you didn't buy from us, we want this tool to be useful to you.

Within +/-5% for major OEMs (Cummins, Kirloskar, Cat, Perkins) and +/-6% for the generic CPCB IV+ curve. The result page shows this as a confidence band on the monthly cost - for example, 'Rs 1.20 L to Rs 1.32 L'. Our SFC curves are cross-checked against publicly available manufacturer datasheets, EPA Tier 4 Final equivalents, and ICAI / BIS application notes. For a binding fuel guarantee, share your specific OEM SFC datasheet and we'll refine the estimate. For Greaves we use brochure-grade numbers and the tolerance drops to +/-3%.

SFC measures how many grams of diesel an engine burns per kWh of electrical output. Lower SFC = more efficient. A modern CPCB IV+ engine hits around 205-215 g/kWh at the 75% load sweet spot, where combustion is optimal. At 25% load the same engine runs 'rich' and burns 280-310 g/kWh - one reason oversized gensets waste so much fuel. At 100% load efficiency drops slightly because of higher exhaust losses. The calculator interpolates linearly between the four ISO 8528 standard load points (25/50/75/100%) so the L/hr you see reflects your actual operating point, not just nameplate consumption.

At 75% load on a CPCB IV+ engine: a 125 kVA Greaves consumes ~22-24 L/hr, a 250 kVA ~45-48 L/hr, a 500 kVA ~88-92 L/hr, and a 1000 kVA ~175-185 L/hr. At 50% load these numbers drop roughly 30%. At 25% load they drop another 20% but per-kWh efficiency gets worse. These are useful sanity-check numbers - run the calculator with your exact kVA and load profile for a precise answer including monthly cost.

At Rs 95/L diesel and a CPCB IV+ engine running at 75% load, fuel cost works out to roughly Rs 14-16 per kWh delivered. India industrial grid tariff is typically Rs 6-11 per kWh - so diesel is 1.5x to 2.5x dearer. That's why diesel gensets should be used as backup for power outages, not as a primary source. The calculator shows this premium explicitly so you can plan when to start the DG (peak-shaving may not save money if your tariff is below Rs 12/kWh) and prioritise grid uptime improvements or solar+battery alternatives where they're available.

Five proven strategies. (1) Right-size the genset - oversized DGs run at 25-30% load and waste 20% fuel; use our sizing calculator to check. (2) Quarterly AMC tuning - dirty injectors, clogged air filters, and fouled turbo compressors raise SFC by 10-15%. (3) Run at the 70-85% load sweet spot - load-share between two smaller sets if needed. (4) Switch to dual-fuel (diesel + PNG/CNG) - cuts diesel use 30-40% with payback in 18-30 months for high-runtime sites. (5) Schedule preventive maintenance during low-demand windows so you don't burn fuel during overhauls. We can help with all of these.

Each litre of HSD diesel releases 2.68 kg of CO2 when combusted (DEFRA / IPCC 2024 standard factor). So a 250 kVA genset running 8 hours/day at 70% load burns ~340 L/day, releasing ~910 kg CO2/day - or about 22 tonnes CO2/month. Larger sets and continuous-duty operations push this much higher. The calculator shows your monthly + yearly CO2 footprint so you can include it in ESG reporting, BRSR submissions, and Scope 1 emission inventories. For green-building credits (LEED, IGBC), this number is what you report.

Common reasons. (1) Engine condition - a 5+ year old genset with delayed AMC can show 10-20% higher SFC than brochure values; a load bank test will quantify. (2) Wet-stacking from running at low load (<30%) for too long degrades injectors; a service+load test resets it. (3) Fuel quality - watered or adulterated diesel burns inefficiently; switch supplier and use a fuel polishing system. (4) Auxiliary loads - jacket water heaters, battery chargers, and canopy fans can consume 1-3% extra. (5) Frequent start-stop cycles - each cold start consumes 5x the steady-state SFC for the first 60 seconds. The calculator assumes a healthy CPCB IV+ engine running at the chosen steady-state load; share your actual fuel-log data with us and we'll diagnose.

Yes, that's one of its primary uses. Enter the rental kVA, pick the brand (Alpha Diesels rental fleet uses Greaves and Cummins predominantly), set your expected load + run hours, and use your project diesel allowance. The monthly cost output equals your fuel-only OPEX. Add the daily/weekly rental charge separately for total cost. For multi-month rental jobs we can supply a sealed fuel log + per-shift consumption summary as part of our rental contract - useful for back-to-back invoicing on construction and event projects.

Three reasons. First, credibility - serving only Greaves users would limit the tool's utility and our reputation for unbiased technical advice. Second, customer journey - many users come to us because they need help with their existing non-Greaves DG (AMC, repair, fuel polishing, dual-fuel retrofit). Third, transparency builds trust - by clearly marking which numbers are verified vs typical, we let users decide for themselves what tolerance they need. If you eventually decide to upgrade to a Greaves CPCB IV+ set we'll be happy to help, but the tool should be useful regardless.

Yes - choose the 'Older CPCB II / III genset' brand option. Pre-2024 emission-norm engines are 10-15% less fuel-efficient than CPCB IV+ for the same load (typical SFC 245-270 g/kWh at 75% vs 215 g/kWh for CPCB IV+). The CO2 footprint is correspondingly higher. Many sites discover that the upgrade-to-CPCB-IV+ payback period is 3-5 years on fuel savings alone for high-runtime operations, even before accounting for the regulatory pressure. Run both scenarios in the calculator to see the delta for your specific load profile.