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Strength Volume Power to Weight Estimator

The Strength Volume Power to Weight Estimator approximates mechanical power from a repeated lifting effort and then divides that power by body weight. It is designed for users who want a simple way to compare how quickly external work is performed relative to body size, especially when tracking the same exercise, range of motion, and timing method over time.

The estimate uses load, repetition count, vertical displacement per repetition, elapsed time, and body weight. It captures only the external mechanical work represented by moving the entered load through the entered distance; it does not measure true human metabolic power, bar-path complexity, acceleration, or work done moving your own body. For useful comparisons, keep the exercise and measurement method consistent between sessions.

Calculator inputs

kg
m
s
kg
Result
—
Estimated power-to-weight
Estimated work—
Average power—
Power / body weight—

1. Enter the external load
Use the load being moved, excluding body weight unless the movement specifically requires you to include it.

2. Count completed repetitions
Enter the repetitions performed during the measured interval.

3. Estimate vertical travel
Enter the average vertical displacement of the load for one repetition in meters.

4. Time the effort
Use the elapsed seconds for the repetitions being analyzed, including pauses if they are part of the set.

5. Add body weight and compare
The result reports average external mechanical power per kilogram of body weight; compare like-for-like exercises for the best signal.

Work = Load × 9.80665 × Vertical distance × Repetitions Average power = Work ÷ Elapsed time Power-to-weight = Average power ÷ Body weight

Where:
Load = external mass in kilograms
9.80665 = standard gravitational acceleration in m/s²
Vertical distance = average upward displacement per repetition in meters
Elapsed time = seconds for the measured repetitions
Body weight = athlete mass in kilograms

Assumptions: The calculation treats each repetition as lifting the load vertically through a constant distance and ignores acceleration changes, lowering-phase work, bar path, and movement of body segments.

What the result means

A higher W/kg value means more estimated external mechanical power was produced per kilogram of body weight during the measured effort.

This is best used for repeated testing of the same lift and setup rather than comparing unrelated exercises.

Given:
Load: 80 kg
10 repetitions
0.50 m vertical distance per rep
20 s elapsed time
75 kg body weight

Calculation:
Work = 80 × 9.80665 × 0.50 × 10 = 3,922.66 J
Average power = 3,922.66 ÷ 20 = 196.13 W
Power-to-weight = 196.13 ÷ 75 = 2.62 W/kg

Result:
2.62 W/kg

Interpretation: For this set, the model estimates about 2.62 watts of external mechanical power for each kilogram of body weight.

Should I include the lowering phase?

No. This simplified model uses upward displacement only. Including detailed eccentric work would require a more complete motion and force model.

How do I measure vertical distance?

Use a consistent estimate from the start to the top position of the load, ideally measured from video or equipment dimensions. Consistency matters more than extreme precision for trend tracking.

Does a higher W/kg always mean better strength?

No. Power-to-weight reflects how quickly work is done relative to body mass; maximum strength and technical skill are different qualities.

Can I compare a squat with a bench press?

You can calculate both, but the numbers are not directly equivalent because travel distance, muscle mass, technique, and body contribution differ. Compare the same movement whenever possible.

Why is this not the same as a velocity-based training device?

A velocity device directly measures bar speed and can estimate power from motion data. This calculator infers average power from distance, repetitions, load, and total time.