Generator Running Cost Calculator South Africa
Calculate how much it costs to run a generator per hour, per day and per month. Compare generator costs with Eskom electricity prices.
Most home generators run at 25-50% load. 100% is maximum rated output.
Your Generator Running Costs
Generator vs Eskom: Cost Comparison
| Generator | Eskom | Difference | |
|---|---|---|---|
| Cost per kWh | R18,38 | R3,50 | 5.3x more |
| Daily cost (8.0 kWh) | R147,00 | R28,00 | +R119,00 |
| Monthly cost (176 kWh) | R3 234,00 | R616,00 | +R2 618,00 |
How Much Does It Cost to Run a Generator in South Africa?
Running a generator in South Africa can be expensive, especially during extended periods of load shedding. The cost depends on several factors: the generator size (kVA), fuel type (petrol or diesel), current fuel prices, how many hours you run it per day, and the electrical load you place on it. As of March 2026, petrol costs approximately R24.50 per litre and diesel around R22.50 per litre. A typical household running a 5kVA generator for 4 hours a day at 50% load will spend over R3,000 per month on fuel alone — significantly more than the equivalent Eskom electricity would cost.
Generator Fuel Consumption Guide
Fuel consumption varies significantly depending on the size of your generator and how much load you place on it. Here is a reference table for common generator sizes at 50% load:
| Generator Size | Fuel (L/hr) at 50% Load | Petrol Cost/hr | Diesel Cost/hr |
|---|---|---|---|
| 2 kVA (Small/Portable) | 0.7 L/hr | R17,15 | R15,75 |
| 3 kVA | 1.0 L/hr | R24,50 | R22,50 |
| 5 kVA | 1.5 L/hr | R36,75 | R33,75 |
| 6.5 kVA | 2.0 L/hr | R49,00 | R45,00 |
| 8 kVA | 2.5 L/hr | R61,25 | R56,25 |
| 10 kVA | 3.0 L/hr | R73,50 | R67,50 |
| 15 kVA | 4.5 L/hr | R110,25 | R101,25 |
| 20 kVA | 6.0 L/hr | R147,00 | R135,00 |
These figures are approximate averages. Your actual consumption may vary based on the brand, model, age and condition of your generator. Running at a higher load (75-100%) will use significantly more fuel, while running at 25% load will be more economical. Diesel generators tend to be more fuel-efficient than petrol models, especially for larger sizes.
Choosing the Right Generator Size
Selecting the right generator size is important — too small and it will be overloaded, too large and you waste fuel. Here is a general guide:
- 2-3 kVA: Lights, phone chargers, a laptop, and a small TV. Good for basic essentials during load shedding.
- 5 kVA: All of the above plus a fridge, a few more lights, and a Wi-Fi router. The most popular choice for homes.
- 6.5-8 kVA: Can handle a microwave, kettle (not at the same time), and most household appliances except high-draw items.
- 10-15 kVA: For larger homes that want to run most appliances including air conditioning.
- 20 kVA: For very large homes or small businesses that need to run virtually everything.
Tip: Never run a generator at more than 80% of its rated capacity for extended periods. This shortens the lifespan and increases fuel consumption. If in doubt, choose the next size up.
Frequently Asked Questions
How much fuel does a generator use per hour?
Generator fuel consumption depends on the size and load. A small 2kVA generator uses about 0.7 litres per hour at 50% load, while a larger 10kVA unit uses around 3 litres per hour. At full load (100%), consumption increases by approximately 85% compared to half load. Use the calculator above to get a precise estimate for your setup.
How much does it cost to run a 5kVA generator?
A 5kVA generator uses approximately 1.5 litres of fuel per hour at 50% load. At current South African petrol prices of around R24.50/litre, that costs about R36.75 per hour, or R147 for 4 hours of daily use. Over a month of 22 days, the fuel cost would be approximately R3,234 — and that does not include maintenance and oil.
Is it cheaper to use a generator or Eskom?
Eskom electricity is significantly cheaper than running a generator. Eskom residential tariffs average around R3.50 per kWh, while generator electricity costs between R8 and R25 per kWh depending on the generator size and load factor. That means running a generator can cost 3 to 7 times more than Eskom power for the same amount of electricity. Generators make sense as a backup, not as a primary power source.
How much diesel does a generator use per hour?
Diesel generators are slightly more fuel-efficient than petrol models. A 5kVA diesel generator uses about 1.3-1.5 litres per hour at 50% load, while a 10kVA uses about 2.5-3 litres per hour. Diesel is also cheaper per litre in South Africa (approximately R22.50 vs R24.50 for petrol), making diesel generators more economical to run, particularly for larger units.
What size generator do I need for my house?
For basic essentials (lights, fridge, TV, phone charging), a 3-5 kVA generator is sufficient. If you need to run additional appliances like a microwave or kettle, consider 5-6.5 kVA. For a full household including air conditioning, you may need 8-15 kVA. A 2 kVA portable unit is enough for just lights and device charging. Remember that the startup draw of appliances like fridges and motors can be 2-3 times their running wattage.
How long will 20 litres of fuel last in a generator?
The runtime depends on generator size and load. A 2kVA generator at 50% load uses 0.7L/hr, so 20 litres would last about 28 hours. A 5kVA at 50% load uses 1.5L/hr, giving about 13 hours. A 10kVA at 50% load uses 3L/hr, providing roughly 6.5 hours of runtime. Running at a lower load percentage will stretch your fuel further.
Fuel prices and Eskom tariffs are approximate and may vary by region. Generator consumption figures are averages and may differ based on brand, model, altitude and condition. Last updated March 2026.
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