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Generator Size Calculator

Calculate the right generator size for your home or business. Select your appliances and get an instant KVA recommendation. Built for African power realities.

KVA SizingAfrican AppliancesStartup Surge
Your Appliances
Generator Recommendation
Running Watts
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Startup Watts (Peak)
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Recommended KVA
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Power Factor
0.8

Power in Africa

Power instability is a daily reality across much of Africa. Nigeria alone has over 60 million generators in use. Choosing the right size saves fuel costs and protects your appliances.

Undersized generator: Overloads, trips, and damages appliances and the generator itself.

Oversized generator: Wastes fuel, increases purchase cost, and may cause wet stacking (diesel).

Sweet spot: Generator should run at 50-75% of capacity for optimal efficiency and lifespan.

KVA vs KW

KW (Kilowatts) = actual power consumed by your appliances.

KVA (Kilovolt-Amperes) = apparent power the generator must produce.

KVA = KW / Power Factor

Most generators have a power factor of 0.8, meaning a 10 KVA generator delivers about 8 KW of usable power.

How to Size a Generator for Your Home or Business

Choosing the right generator size is critical in countries with unstable power supply. An undersized generator will overload and potentially damage your appliances, while an oversized one wastes money on purchase and fuel. This calculator helps you find the sweet spot by totalling the wattage of all your appliances and accounting for startup surge requirements.

Understanding Startup Surge

Many appliances, especially those with motors (air conditioners, refrigerators, pumps, washing machines), require significantly more power to start than to run continuously. This startup surge can be 2-3 times the running wattage. Your generator must handle this peak load, even though it lasts only a few seconds. This calculator automatically factors in surge requirements.

Generator Types Common in Africa

Backup power workflow

Turn appliance load into a buyer-ready generator spec

Not sure how to get the most from the Generator Size Calculator? Enter your measurements and quantities and it returns a costed material and labour estimate — built for all 54 African countries.

  • What you get: a costed material and labour estimate, so you can move from a quick look to a real decision.
  • How it works: the Generator Size Calculator takes your measurements and quantities and shows the working, not just a single number.
  • What to check: confirm current local material prices and site specifics before you rely on the result.

Reviewed 2026. Results are a guide — always confirm current local material prices and site specifics before acting.

Generator Size Calculator FAQ

How do I use the Generator Size Calculator?

Enter your measurements and quantities in the fields above. The Generator Size Calculator then gives you a costed material and labour estimate you can use straight away.

How accurate is the Generator Size Calculator?

It is as accurate as the values you enter and shows the assumptions behind the result. Always confirm current local material prices and site specifics before you rely on it.

Is the Generator Size Calculator free, and does it cover my country?

Yes — it is completely free, works on any phone or computer with no signup, and is built for all 54 African countries.

Frequently Asked Questions

What size generator do I need for a 3-bedroom flat in Nigeria?
A typical 3-bedroom flat running lights, fans, TV, refrigerator, and a few small appliances needs about 2.5-3.5 KVA. Add an AC unit and you'll need 5-7.5 KVA. Add multiple ACs and you're looking at 10+ KVA.
Why does my generator trip when the AC starts?
Air conditioners have a high startup surge — typically 2-3 times their running wattage. If your generator is only sized for running watts, the surge will overload it. You need a generator rated for the combined running watts plus the highest single startup surge.
Is it better to buy one large generator or two small ones?
One properly sized generator is usually more efficient and cost-effective. However, for businesses needing redundancy, two generators with an automatic changeover can provide backup if one fails. Some setups use a small generator for low-load periods and a larger one for peak times.
Backup power check

Verify the load schedule before buying a generator

Use the appliance list, running watts, surge watts, power factor, and headroom to create a quote-ready generator sizing brief.

Reviewed 2026

Local-first estimate. No live quote or official approval is performed.

What to check

  • Methodology: sum running watts, model startup surge, convert to kVA with the displayed power factor, then add practical headroom.
  • Confirm appliance labels, motor startup surge, phase, AVR/inverter quality, transfer switch, earthing, ventilation, noise, fuel type, and local technician advice.
  • Copy or download the load schedule before asking suppliers for quotes so every quote is based on the same appliance list.

Limitations

  • Disclaimer: planning estimate only, not an electrical certificate, safety sign-off, installer quote, warranty, or official power standard.
  • Real generator performance varies by altitude, heat, fuel quality, maintenance, load balance, and manufacturer surge rating.
  • Source/reference note: verify against current manufacturer datasheets, electrician guidance, local wiring codes, and safety rules before installation.
Review result panel

Privacy note: the calculator runs in your browser. Do not paste account numbers, installer contracts, or private customer data into notes you plan to share.