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Inverter generator · tri-fuel In stock · ships from Dallas

GENMAX GM12500iET 12500W Tri-Fuel Inverter Generator with CO Shield

12,500-watt tri-fuel inverter with a 458cc engine, a 50A outlet, and 2-wire auto start.

5.0 (4 reviews)

$1,439.40 $2,799.00 SAVE $1,359.60 (49% OFF)

In stock · ready to ship Ships tomorrow Order today and it leaves our Dallas, TX warehouse tomorrow.

Tracking number sent by email as soon as the freight carrier picks up your order.

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3-year warranty
30-day returns
Free delivery

Starting watts

12,500 W

On gasoline

Running watts

9,500 W

On gasoline

Fuel

Tri-fuel

Gasoline, Propane, Natural gas

Engine

458 cc

Overview

A 458cc tri-fuel inverter with a 50A outlet.

The GM12500iET uses a 458cc engine and a 6.1-gallon tank. On gasoline it is rated at 12,500 starting watts and 9,500 running watts, and it also runs on propane and natural gas from a separate inlet. GENMAX lists eco-mode noise as low as 62 dBA at 25% load and runtime up to 10.4 hours. Outlets include a 14-50R 50A, a 30A, and a 20A, plus 12V DC and USB. It starts electrically, from a 2-wire auto-start lead, from the Bluetooth app, or with the recoil. A CO sensor is built in.

50A 14-50R Plus 30A and 20A outlets.
Up to 10.4 hours On a 6.1-gallon tank at light load.
CO sensor EPA compliant.

GENMAX GM12500iET · Feature 1

Three fuel choices

Gasoline, Propane, Natural gas

GENMAX GM12500iET · Feature 2

A panel for different loads

14-50R 50A 120/240V, 30A, 20A, 12V DC, USB

GENMAX GM12500iET · Feature 3

Remote and automatic starting

Electric, 2-wire auto start, Bluetooth app, recoil

GENMAX GM12500iET

Specifications

Figures for this model. If you need a detail that isn’t listed, ask us and we’ll check before you order.

Ask about this model

Model	GENMAX GM12500iET
Type	Inverter generator
Fuel	Gasoline, Propane, Natural gas
Starting watts	12,500 W gasoline
Running watts	9,500 W gasoline
Engine	458cc OHV
Fuel tank	6.1 gal
Runtime	Up to 10.4 hours at light load
Noise	As low as 62 dBA at 25% load
Outlets	14-50R 50A 120/240V, 30A, 20A, 12V DC, USB
Starting	Electric, 2-wire auto start, Bluetooth app, recoil
Safety	CO sensor
Warranty	3-year limited, per GENMAX

Customer reviews

Reviews from GENMAX GM12500iET owners.

5.0

Based on 4 reviews

100% (4)

0% (0)

Customer photos (3)

Mark R.

Runs whole house including 4-ton AC without flinching

David M.

Clean freight delivery and great build quality

Travis H.

Fuel versatility is a complete lifesaver

Mark R.

Tyler, TX

October 24, 2026

★★★★★

Runs whole house including 4-ton AC without flinching

Ordered the GENMAX GM12500iET 12500W Tri-Fuel Inverter Generator with CO Shield after getting tired of sitting in the dark during Gulf storms. Freight delivery arrived on a liftgate truck right onto my concrete driveway. Hooked it into our manual transfer switch with a 50A cord and ran our central 4-ton AC, two refrigerators, well pump, and all household lights. Electric start fired right up on propane.

David M.

Broken Arrow, OK

October 12, 2026

★★★★★

Clean freight delivery and great build quality

Driver called me 24 hours ahead of time to coordinate delivery. Unit was bolted onto a heavy pallet and wrapped securely. Added oil, connected a 100-lb propane tank, and pushed the start button. Purrs like a kitten and the digital meter makes monitoring voltage and hours simple. Couldn't ask for a better machine at this price point.

Travis H.

Ocala, FL

September 28, 2026

★★★★★

Fuel versatility is a complete lifesaver

The tri-fuel capability was the main selling point for me. Being able to connect directly to our residential natural gas line means no more storing 50 gallons of stale gasoline in the garage. Build quality is solid industrial grade and the frame feels bulletproof.

Gary W.

Marysville, OH

September 15, 2026

★★★★★

Remote start key fob works from inside the house

Tested the wireless remote start from about 80 feet away through the back patio door—started immediately. It is surprisingly quiet for an engine of this displacement. Very impressed with the packaging and complete hardware kit included.

GENMAX GM12500iET

Questions and answers

Can’t find what you need? Send us a message and we’ll get back to you.

What fuels does the GM12500iET run on?

It runs on gasoline (12,500 W starting, 9,500 W running), propane, and natural gas.

Can it back up my house?

The 50A 120/240V outlet is the connection normally used with a home transfer switch or interlock kit. Have a licensed electrician size and install that connection.

What are the propane and natural-gas watt ratings?

It runs on both, from a separate inlet. GENMAX publishes the 12,500 / 9,500 watt gasoline rating on this model and does not print separate propane and natural-gas watt figures on the same spec line, so those are not listed here.

How does delivery work?

Delivery is free to residential addresses. Orders ship from our Dallas, TX warehouse, and larger items arrive by freight with a liftgate drop at your curb or driveway. You get a tracking number by email as soon as the carrier picks up your order.