Router power question

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Forum topic by bbasiaga posted 03-02-2017 05:28 PM 563 views 0 times favorited 7 replies Add to Favorites Watch
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1243 posts in 2531 days

03-02-2017 05:28 PM

I have what I hope does not turn out to be a dumb question. All handheld routers are 110v in the US, at least that I know of. But some are sold as 1.5hp, 2.5hp, 3.25hp…

We know that a 20amp 110v circuit tops out at about the 1.5hp mark, so what is the real difference between these routers? I am gone it must just be the amount t of torque the motor turns out, allowing it to run bigger bits. Thoughts?


-- Part of engineering is to know when to put your calculator down and pick up your tools.

7 replies so far

View Madmark2's profile


538 posts in 1124 days

#1 posted 03-02-2017 05:37 PM

Router power figures are inflated like the wonderbra. Torque is what counts.

Big (3+ hp) routers need variable speed to slow down for large diameter cutters. Small routers (~1 hp) tend to run full tilt all the time.

Big routers live in tables, small and medium routers you can free hand.

You’ll spend more on bits than routers.


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10859 posts in 2022 days

#2 posted 03-02-2017 05:38 PM

It does for an induction motor but universal motors are measured differently.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

View Rrrandy's profile


212 posts in 1015 days

#3 posted 03-02-2017 05:45 PM

Watts=current * voltage

1 watt = .00134 hp

-- Y'all need to locate a sense of humor. Borrow one if you can't find yours...

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6065 posts in 2257 days

#4 posted 03-02-2017 06:16 PM

You will almost all of the time get more torque out of a universal motor that is larger in diameter due to the longer effective torque arm from the center of the shaft to the OD of the armature. There is no fixed motor OD to armature OD ratio that every manufacturer is going to exactly follow so that coupled with countless other variables can make a direct comparison difficult. I have noticed that many of the 3+ HP routers are more likely to have a maximum speed at or under 25K rpm whereas those at 2 1/4 HP or less tend to be over 25k rpm. This makes sense as few people weould want to hold a 3 1/4 HP router while running a 1/4” radius round over bit through soft wood, it would not only be extreme overkill but quite fatiguing as well.

-- "Lack of effort will result in failure with amazing predictability" - Me

View Rich's profile


5001 posts in 1125 days

#5 posted 03-02-2017 10:32 PM

They generally do those tests using measurements of start-up current, or for a lock-rotor measurement, where the current is high. The tests only last a second or so. That’s how 12 amp motors get rated at 2-1/4 hp and higher. The inrush current is higher that 12A, so they use that for the horsepower calculation. I’ve seen 15A motors that were “rated” at 5 hp on the adhesive label stuck to the front of the machine in the store.

View MrUnix's profile


7499 posts in 2735 days

#6 posted 03-02-2017 11:30 PM

I’ve seen 15A motors that were “rated” at 5 hp on the adhesive label stuck to the front of the machine in the store.
- RichTaylor

Like my “5.5HP” shop vac that runs on a standard 15A 120v wall outlet :) It’s gotta be true, as it’s printed right there on the front of the thing in big bold letters!


-- Brad in FL - In Dog I trust... everything else is questionable

View Mikenln's profile


13 posts in 1308 days

#7 posted 03-02-2017 11:38 PM

The horsepower of a router is determined by the marketing department. The engineering department determines the amps.

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