Cycleops has a nice Watt per Kilogram Tool.

I calculated a good hill climb(strava) I did this year and got 4.7 Watts per Kg. This seems really high.

What is Power?

Power is the total energy or work an athlete is able to produce in a given time frame. On the Power Tap, work is measured as the force exerted on the rear hub times the distance traveled by the hub (Work = Force x Distance) while power is simply the total work divided by time and expressed as a watt or joule per second (Power = Work / Time = Force x Distance / Time = Watt) Since a given distance divided by time is essentially speed, (Power = Force x Speed). In practical terms, power is a combination of how hard and how fast a cyclist pushes on the pedals or how fast an athlete can overcome all the forces holding her back. Those forces include wind, gravity, and the junction where rubber literally hits the road. Accordingly, the power an athlete needs for a given speed is dependent upon factors like weight, aerodynamic drag, the road surface, and tires. Because these factors are different for everyone, when comparing athletes, power is best expressed as a power to weight ratio for climbing or a power to drag ratio for riding on the flats (Table 1).

Key:

Power = Work/Time = (Force x Distance)/Velocity = Force x Speed = Torque x Angular
Power = Joule/second = Watt
The Watts Calculator takes into account the main variables that effect power output on a bike.

Power Output to Weight (Watts per Kg) at Lactate Threshold

Gender Female Male
USCF Category 4-5 2.5 to 3.0 3.0 to 3.5
USCF Category 2-3 3.0 to 3.5 4.0 to 4.5
US Domestic Professional 3.5 to 4.0 4.5 to 5.0
Successful Pro Tour Pro 4.0 to 4.5 5.0 to 5.5