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Generator Amperage Reference Chart

Navigate the electrical requirements of your project with Stag Power Rentals’ Amperage Chart. Ensure you have the right power supply for your equipment with this valuable resource.

Amperage Shown for 3 Phase at 80% Power Factor

Note: The values in this amperage table are estimates for three-phase generator operation. Actual amperage from a diesel generator can vary depending on voltage, load, power factor, generator rating, and operating conditions. The generator’s alternator and electrical configuration can also affect its rated output, so use the chart as a reference rather than an exact measurement.

KVa kW 208V 220V 240V 480V 600V 4160V
31.3 25 87 82.5 75.5 37.8 30 4.4
37.5 30 104 99 90.3 45.2 36 5.2
50 40 139 132 120 60 48 7
62.5 50 173 165 152 76 61 8.7
75 60 208 198 181 91 71 10.5
93.8 75 261 247 226 113 90 13
100 80 278 264 240 120 96 13.9
125 100 347 330 301 150 120 17.5
156 125 433 413 375 188 150 22
187 150 520 495 450 225 180 26
219 175 608 577 527 264 211 31
250 200 694 660 601 301 241 35
312 250 866 825 751 376 300 43
375 300 1040 990 903 451 361 52
438 350 1220 1155 1053 527 422 61
500 400 1390 1320 1203 602 481 69
665 500 1735 1650 1504 752 602 87
750 600 2080 1980 1803 902 721 104
875 700 2430 2310 2104 1052 842 121
1000 800 2780 2640 2405 1203 962 139
1125 900 3120 2970 2709 1354 1082 156
1250 1000 3470 3300 3309 1504 1202 174
1563 1250 4350 4130 3765 1885 1503 218
1875 1500 5205 4950 4520 2260 1805 261
2188 1750 5280 2640 2106 304
2500 2000 6020 3015 2405 348
2812 2250 6780 3400 2710 392
3130 2500 7520 3765 3005 435
3438 2750 8280 4140 3312 478
3750 3000 9032 4516 3613 521
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This generator amperage chart estimates the output amperage of a generator based on its operating power and voltage. Generator ratings are commonly expressed in kW and kVA (kilovolt-amps), while electrical output may also be evaluated using volts and amps. The values shown are estimates rather than exact output because generator capacity and actual performance can vary based on operating conditions, load, power factor, and other factors. Stag Power Rentals strives to offer you all of the resources that you need to understand generators and make the right purchasing decisions.

How to Read This Amperage Chart

Amperage output varies based on three factors: generator kW rating, operating voltage, and power factor. This chart uses a standard power factor of 0.8 (80%) at three-phase configuration — the most common setup for commercial and industrial generator rentals. To find the amperage for your site, locate your generator’s kW rating in the second column, then read across to the voltage column that matches your electrical system.

How Many Amps is a 20kW Generator?

A 20kW generator is not shown in this chart because the smallest unit in Stag’s rental fleet starts at 25kW. At 25kW and 480V three-phase, output amperage is approximately 37.8A. At 240V, that same unit produces approximately 75.5A. If you need a 20kW unit specifically, call 1-844-STAG-PWR to discuss availability.

Single Phase vs Three Phase

This chart reflects three-phase output at 80% power factor — standard for industrial facilities. Single-phase output amperage will be higher for the same kW rating. For single-phase calculations, use the industrial generator sizing calculator.

Understanding kW, kVA, Volts and Amps

Generator capacity can be expressed using several electrical measurements. kW (kilowatts) represents real power available to perform useful work, while kVA (kilovolt-amps) represents apparent power and takes power factor into account. Voltage and phase configuration also affect how many amps a generator can supply.

For commercial and industrial applications, understanding the relationship between kVA, kW, volts and amps helps determine the appropriate generator rating for the equipment being powered. Motors, pumps and other equipment can also require additional starting watts compared with their normal running watts, so amperage should not be the only factor considered when sizing a generator.

Power Out Due To A Hurricane?

If a hurricane has left your business without power call us. We can guide you through the generator rental process and help restore power to your business with as little downtime as possible. 

If you want to get ahead of power outage, then signup for our Hurricane Contingency Plan >

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