Electric vs Cordless Plane Power Output: What the Numbers Mean
A 6.5 amp corded plane drawing 780 watts. An 18V cordless pulling 40 amps for 720 watts. Nearly identical electrical input. Dramatically different cutting behavior in actual wood. The specification sheet captures everything about the electricity going into these tools and almost nothing about the cutting coming out.
The Spec Sheet Performance
Amp ratings on corded planes measure current draw - energy flowing into the motor, not mechanical power reaching the blade. A 6.5 amp tool on 120 volts draws 780 watts. But universal motors inside corded planes convert electricity to mechanical power at 70-85% efficiency. That 780-watt input produces maybe 550-650 watts of actual cutting force.
Two tools with identical amp ratings can perform completely differently. Motor design, winding quality, bearing friction - invisible factors determining how much electricity becomes cutting versus how much becomes heat and noise. The amp number tells you what goes in. Says nothing about what comes out.
RPM specifications add another layer of misdirection. The "16,500 RPM" on the box represents no-load speed - the motor spinning freely in air. Under cutting load, that number drops. A strong motor might hold 15,000 RPM through moderate hardwood. A weaker motor with identical no-load specs drops to 13,000. That 13% speed loss shows up as rougher surfaces and slower work, but both tools wear the same number on the label.
The Voltage Marketing Game
Cordless specifications play their own numbers game. DeWalt's "20V MAX" battery and Makita's "18V" battery are functionally identical platforms. The difference is marketing convention - 20V MAX refers to peak voltage when fully charged, 18V represents nominal voltage during typical discharge. Same battery chemistry, same operating range, different sticker.
Battery capacity determines runtime, not power. A 2.0Ah pack and a 6.0Ah pack at identical voltage deliver the same instantaneous cutting force. The larger pack just sustains it three times longer.
The real cordless advantage lives in the motor. Most modern cordless planes run brushless motors achieving 85-90% efficiency - significantly better than the 70-85% of brushed motors in corded tools. An 18V cordless producing 720 watts electrical input might deliver 615-650 watts mechanically, roughly matching a 6.5 amp corded tool despite lower total wattage. More of the battery's energy reaches the blade.
What the Numbers Can't Show
The specification-invisible factors often matter more than the specifications themselves.
Gearing ratios determine the speed-versus-torque balance. Two planes listing identical 15,000 RPM might achieve it through completely different motor speeds and gear reductions. Higher reduction ratios deliver more torque at the blade - more authority through dense hardwood. Lower ratios produce higher surface speed for smoother finishes in cooperative wood. The RPM spec matches. The cutting behavior doesn't.
Blade mass creates rotational inertia that carries cutting edges through knots and grain changes. Heavier blades maintain speed better when resistance spikes. Lighter blades respond faster but bog down easier. No manufacturer lists blade mass on the box.
Bearing quality converts motor power to cutting or to friction heat. Premium sealed ball bearings lose maybe 2-3% of shaft power. Cheap bearings waste 5-10%. Two identical motors, different bearings, noticeably different cutting performance. The difference between a $90 plane and a $200 plane often lives in components nobody photographs for the product listing.
Battery Behavior in Practice
Cordless planes face progressive power loss through the discharge cycle. A fully charged 18V battery might deliver 20 volts under load. At 50% capacity, that drops to 17 volts. Near depletion, loaded voltage falls below 15. The plane that cut hardwood confidently with a fresh battery struggles through pine at the end of the charge.
Quality tools compensate by drawing more current as voltage drops, maintaining consistent power until the battery gives out suddenly rather than fading. Budget tools show the fade in real time - the blade audibly slows through the discharge cycle.
Cold weather compounds the problem. Lithium-ion batteries deliver roughly 70-80% of rated power at 32 degrees Fahrenheit, dropping to 50% or less at zero. Meanwhile, cold wood cuts harder - increased cell wall stiffness and moisture approaching freezing. The double penalty of less available power meeting increased cutting resistance can reduce effective performance to 60% of warm-weather capability.
Corded planes don't care. 120 volts from the wall doesn't fade through a work session, doesn't need charging, doesn't lose power in January. The cord is the limitation and the advantage simultaneously.
Where the Gap Closes
For intermittent work - trimming doors, fitting shelving - modern brushless cordless planes match corded performance closely enough that the differences barely register. The motor efficiency advantage offsets battery limitations during short tasks.
For sustained heavy use through dense hardwood species, the math still favors cords. Continuous cutting drains batteries fast, and progressive voltage drop means the last twenty minutes of battery life deliver noticeably less than the first twenty. A corded plane delivers the same cut at hour three that it delivered at minute three.
The spec sheet comparison looks like a close contest. The real-world comparison depends entirely on what kind of work fills the day.