Watch Power Reserve Calculator

Calculate power reserve duration, winding efficiency, and compare automatic vs manual winding for your mechanical watch.

Power Reserve Estimator

Estimate remaining power reserve based on last wind and usage pattern.

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hours
hrs/day

Winding Efficiency Calculator

Calculate how efficiently your automatic watch winds based on your activity level.

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steps
hrs/day

Automatic vs Manual Wind

Compare power reserve behavior between automatic and manual wind watches.

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hours
days
turns
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Formula

Remaining Reserve = Max Reserve - Hours Elapsed + (Winding Input) | Winding Rate = Steps x Rotor Efficiency / Required Rotations x Max Reserve

Frequently Asked Questions

What is a good power reserve for a mechanical watch?
Standard is 38-48 hours. Good is 60-72 hours (weekend-proof). Extended reserves of 80-120+ hours are found in premium movements. Some exceptional movements offer 8+ days of power reserve.
Does wearing an automatic watch keep it fully wound?
It depends on your activity level. An active person wearing the watch 10+ hours daily typically generates enough motion. Sedentary desk work may not generate sufficient winding. Walking generates roughly 500-600 rotor rotations per hour.
How many times should you wind a manual watch?
Most manual-wind watches need 20-40 full crown turns to reach full power reserve. Wind until you feel firm resistance but never force past this point. Winding once daily at the same time creates a consistent routine.

Understanding Watch Power Reserve

Power reserve is the amount of time a fully wound mechanical watch will continue to run. It is determined by the mainspring length, barrel size, and the movement's energy consumption. Understanding power reserve helps you maintain your watch properly and choose the right watch for your lifestyle.

Power Reserve Categories

Standard (36-48 hours): Most common. Requires daily wearing or winding. Examples: ETA 2824, Sellita SW200.

Extended (60-80 hours): Weekend-proof. Can sit unworn from Friday evening to Monday morning. Examples: Rolex Cal. 3235 (70hr), Tudor MT5602 (70hr).

Long (80-120 hours): Multi-day reserve for rotation-friendly collecting. Examples: Omega Co-Axial 8900 (60hr), IWC 52010 (168hr).

Ultra-Long (120+ hours): Exceptional engineering, often using multiple barrels. Examples: Panerai P.5000 (192hr), Hublot UNICO (72hr).

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