Caliber
Caliber is the mechanical movement, mainspring, gear train, escapement, balance wheel. Each caliber has a specific reference number (Rolex 3235 in Submariner, 4130 in Daytona, Patek 240 ultra-thin, AP 4302 Royal Oak). Caliber condition: accuracy, amplitude, beat error — moves resale ±15–25%.
Caliber components
Mainspring
Stores energy when wound — drives the watch's power reserve.
- 48–72 hours for modern Rolex
- 65 hours for AP Caliber 4302
- 70 hours for Patek Caliber 26-330 S C
Gear train
Transfers energy from mainspring to escapement.
Escapement
Releases energy in regular pulses via pallet fork and escape wheel.
Balance wheel
Oscillates back and forth — 28,800 vph (4 Hz) for modern Rolex, 21,600 vph (3 Hz) for vintage Patek, 28,800 vph for AP.
Rotor
Rotates to wind the mainspring automatically (automatic movements) — Rolex uses bidirectional, Patek uses platinum rotor.
Critical pre-owned calibers
| Brand | Caliber | Used in | Notable |
|---|---|---|---|
| Rolex | 3235 | Submariner 126610, Datejust 41 | Chronergy escapement, 70hr PR |
| Rolex | 4130 | Daytona 116500/126500 | Vertical clutch, 72hr PR |
| Rolex | 3255 | Day-Date 40 228xxx | Chronergy + 70hr PR |
| Rolex | 3186 | GMT-Master II 116710 (disc.) | True GMT |
| Patek | 240 | Calatrava, Aquanaut | Ultra-thin micro-rotor 2.4mm |
| Patek | 26-330 S C | Nautilus 5711, Aquanaut 5167 | 4Hz, 35-45hr PR |
| AP | 4302 | Royal Oak 15500 | 4Hz, 70hr PR |
| AP | 2120 | Royal Oak 15202 Jumbo | Ultra-thin 2.45mm |
| AP | 2385 | Royal Oak Offshore Chrono | Frederic Piguet 1185 base |
| Omega | 8800/8900 | Seamaster 300M, Aqua Terra | Co-Axial Master Chronometer |
| Omega | 1861/1863 | Speedmaster Moonwatch | Manual wind, lemania base |
Resale impact
Caliber in spec (timegrapher reading normal)
- Amplitude 270–290° = Excellent
- Beat error <0.5ms = Excellent
- Rate ±2 sec/day = Excellent
- Baseline price
Caliber needing service
- Amplitude 200–250° = service within 1 year
- Beat error 0.5–1.0ms = Acceptable
- Rate ±5–10 sec/day = OK
- -3 to -8%
Caliber issue
- Amplitude <200° = service immediately
- Beat error >1.0ms = escapement problem
- Rate ±20+ sec/day = significant problem
- -8 to -15%
Caliber broken
- Not running or running incorrectly
- -15 to -28% (see non-running watch buyback)
Caliber swap (Frankenwatch)
- Caliber from wrong year or reference
- -30 to -50% or declined
Verification
Specialists check:
- Open caseback (watchmaker only), verify caliber number engraving
- Timegrapher — amplitude, beat error, rate
- Visual — rotor, balance wheel, pivots cleanliness
- Power reserve test — full wind, leave 48 hours, check spec
Don't open the caseback
Sellers should never open the caseback themselves:
- Damages gasket
- Reduces water resistance
- Dealer detects immediately — additional -5 to -8%
Leave it to watchmakers or Service Centre when needed.
Send watch photos via LINE — for suspected caliber issues we schedule a watchmaker in-person inspection (free if you sell).
Sources: Rolex Caliber technical specifications · Patek Philippe Caliber documentation · Watchmaker Forum Asia caliber identification guide