Standard Generator Sizes

Generator Sizes kW & kVA — Complete Ladder 8–4,000 kVA

Diesel generator sets are built in a defined ladder of standard sizes, from compact single-phase home units to multi-megawatt industrial installations. This guide lists every standard size from 8 kVA to 4,000 kVA with kW equivalents, typical applications, and practical selection advice.

8–4,000 kVA range

kW & kVA conversion

Prime & standby ratings

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Diesel generator sets from 8 kVA to 4,000 kVA, single-phase and three-phase, 50 or 60 Hz.

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8–4,000 kVA generator range

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kVA to kW Chart

Standard Generator Sizes: Complete kVA to kW Ladder

Generator sets are rated in kVA (apparent power), while your equipment is usually rated in kW (real power). At the standard 0.8 power factor used for industrial generators, the relationship is simple: kW = kVA × 0.8. A 100 kVA generator delivers 80 kW.

Standard Size (kVA)	kW (0.8 PF)	Phase
8	6.4	Single-phase
10	8	Single-phase
15	12	Single-phase
20	16	Single-phase
25	20	Single / 3-phase
30	24	Single / 3-phase
40	32	3-phase
50	40	3-phase
60	48	3-phase
75	60	3-phase
80	64	3-phase
100	80	3-phase
125	100	3-phase
150	120	3-phase
200	160	3-phase
250	200	3-phase
300	240	3-phase
350	280	3-phase
400	320	3-phase
500	400	3-phase
600	480	3-phase
750	600	3-phase
800	640	3-phase
1000	800	3-phase
1250	1000	3-phase
1500	1200	3-phase
2000	1600	3-phase
2500	2000	3-phase
3000	2400	3-phase
4000	3200	3-phase

Note: These are the discrete steps manufacturers actually build. Shandong Huali manufactures across the entire ladder — from a small home standby unit to a 4,000 kVA industrial installation.

Size (kVA)	kW	Example Engine	Fuel (g/kWh)	Reference Weight / Dimensions
30	24	Yuchai YN27GBZ	≤230	700 kg / 2000×860×1200 mm
50	40	Yuchai YN38GBZ	≤225	900 kg / 2200×1000×1500 mm
100	80	Yuchai YN48GBZL	≤210	1,500 kg / 2600×1000×1500 mm
250	200	Cummins 6LTAA8.9-G2	~197	Contact us

Note: Shandong Huali pairs sets with Cummins, Perkins, Weichai, and Yuchai engines and Stamford alternators, so the same size can be configured for different budgets and duty cycles.

Small

8–60 kVA

Single-phase and small three-phase sets for homes, small shops, offices, and light backup.

Medium

60–400 kVA

Three-phase sets for workshops, construction sites, office buildings, data centers, and mid-size factories.

Large

400–4,000 kVA

Industrial and base-load sets for hospitals, large factories, mining operations, and utility-scale standby.

Application	Standard Range	Typical kW
Small home / apartment	5–18 kVA	4–14 kW
Large home / villa (AC)	18–60 kVA	14–48 kW
Small office / retail	10–50 kVA	8–40 kW
Restaurant / small shop	20–50 kVA	16–40 kW
Farm / irrigation (pumps)	20–50 kVA	16–40 kW
Construction site	50–150 kVA	40–120 kW
Machine shop	50–100 kVA	40–80 kW
Office building (5–10k sqft)	80–150 kVA	64–120 kW
Data center (servers + cooling)	100–300 kVA	80–240 kW
Hospital (critical + HVAC)	200–500 kVA	160–400 kW
Factory / manufacturing	100–1,000+ kVA	80–800+ kW
Mining / heavy industrial	1,000–4,000 kVA	800–3,200 kW

Important: These ranges are planning estimates only. Confirm the final size with a complete load schedule and starting sequence.

Application Notes

What Changes the Required Size?

Construction Sites

20–500 kVA

Often operate as prime power. Capacity increases as the project moves to pumps, compressors and heavy equipment.

Warehouses & Factories

100–2,000 kVA

HVAC, conveyors, and machine tools create high continuous loads. Plan reserve for future equipment.

Data Centers & Hospitals

200–4,000 kVA

Critical facilities require standby capacity, redundancy, UPS coordination, and compliance beyond the basic load calculation.

Agriculture & Farms

20–150 kVA

Irrigation pumps and grain-handling motors produce large startup surges. The required generator may be significantly larger than the continuous kW load.

Ratings Explained

Prime vs Standby: Reading kW Ratings

A single generator carries more than one kW number, and confusing them is a common cause of undersizing. The two ratings you'll see most often are: Standby — the higher output for limited hours during outages; and Prime — the output for continuous primary power. As a rule of thumb, prime rating is about 90% of standby.

Standby Rating

The maximum output the generator can supply for limited hours per year, used only during utility outages. This is the higher number.

Higher Output

Prime Rating

The output the generator can supply as the primary power source for unlimited hours at a variable load. Size on this for off-grid, construction, and continuous-duty sites.

Continuous Duty

Prime Rating	Standby Rating
20 kW (25 kVA)	25 kW (31 kVA)
72 kW (90 kVA)	80 kW (100 kVA)
90 kW (113 kVA)	100 kW (125 kVA)
200 kW (250 kVA)	220 kW (275 kVA)

Why this matters: Two suppliers can quote the "same" 100 kVA generator with different kW figures — one quoting prime and the other standby. When you request a quote, tell us how you'll actually run the unit, and we'll size on the correct rating.

STEP 01

List Every Load

Record the running watts of every appliance, motor, and piece of equipment that may operate at the same time, including lights, HVAC, computers, and pumps.

STEP 02

Identify Largest Starting Surge

Motor-driven equipment — compressors, pumps, and air conditioners — can draw 2 to 7 times their running load at startup. Add only the single largest surge.

STEP 03

Convert Running Load to kW, then kVA

Divide total watts by 1,000 to get kW, then divide by 0.8 to get kVA. Use the formula kW = kVA × PF with PF = 0.8.

STEP 04

Add Safety Margin & Pick Next Size

Add 20–30% headroom for standby applications and up to 50% for prime-power or future expansion, then select the next standard size from the ladder above.

Worked Example

80 kW Running Load at 0.8 Power Factor

An 80 kW connected load corresponds to 100 kVA at a 0.8 power factor. Applying a 25% sizing allowance gives 100 × 1.25 = 125 kVA. The practical selection is therefore a 125 kVA generator, equivalent to approximately 100 kW at 0.8 PF.

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Get the Right Standard Generator Size

Shandong Huali Electromechanical Co., Ltd. has manufactured diesel generator sets since 1999, with a range spanning 8 kVA to 4,000 kVA, single- and three-phase, and 50 or 60 Hz. Every unit is 100% load-tested before delivery, certified to ISO9001, CE, and CCC, and exported to more than 20 countries.

Frequently Ask Questions

Q: What are the standard sizes of diesel generators?

A: Standard diesel generator sizes run in a ladder from about 8 kVA up to 4,000 kVA, typically stepping through 10, 15, 20, 25, 30, 40, 50, 60, 75, 80, 100, 125, 150, 200, 250, 300, 400, 500, 600, 750, 800, 1000, 1250, 1500, 2000, 2500, 3000, and 4000 kVA. Small sets are single-phase; larger sets are three-phase.

Q: How many kW is a 100 kVA generator?

A: At the standard 0.8 power factor, a 100 kVA generator delivers 80 kW. The exact figure depends on the power factor of your load.

Q: What is the difference between kVA and kW?

A: kW is the real power your equipment consumes to do work; kVA is the apparent power the generator delivers. They are related by the power factor: kW = kVA × power factor. At 0.8 PF, a 100 kVA generator supplies 80 kW.

Q: What is a 250 kVA generator used for?

A: A 250 kVA generator delivers about 200 kW and is typically used for mid-size factories, large office buildings, cold-storage warehouses, and small hospital or mining-camp backup.

Q: What is a 500 kVA generator used for?

A: A 500 kVA generator delivers about 400 kW and is used for large factories, data centers with N+1 redundancy, hospitals, and heavy construction or mining sites.

Q: What is the difference between standby and prime power rating?

A: Standby is the higher output for limited hours during outages; prime is the output it can supply continuously as the primary source. Prime is roughly 90% of standby.

Q: What is the smallest and largest standard generator size?

A: The smallest practical diesel generator sets start around 5–8 kVA for a home or small shop; the largest industrial units reach 4,000 kVA and beyond. Shandong Huali manufactures across this full range.