Hamilton · Hamilton H-23

Hamilton Khaki Field Power Reserve: inside the hand-wound H-23

The Hamilton Khaki Field Power Reserve Mechanical 40mm runs on the hand-wound H-23, which shows its own fuel gauge on the dial. A full wind lasts about 80 hours, or three and a third days.

Updated September 2026 · Based on manufacturer specs, published reviews and watchmaker/owner reports

Watches that use the H-23

The H-23 is a young movement with one home so far: the Khaki Field Power Reserve Mechanical, a 40 mm field watch Hamilton launched in September 2025. aBlogtoWatch called it the first time Hamilton had offered a power reserve complication in a Khaki watch. Hamilton lists it as the "Khaki Field Mechanical Power Reserve" on some pages and the "Khaki Field Power Reserve" on others. Same watch, same movement.

If you're after the classic 38 mm Khaki Field Mechanical with no gauge, that's the H-50. The automatic Khaki Field Auto uses the H-10.

Specs at a glance

History and where it came from

For years Hamilton's hand-wound field watch was a plain three-hander. The 2019 Khaki Field Mechanical moved to the H-50, an ETA 2801-2 reworked with a slower 3 Hz balance and a longer mainspring for 80 hours of reserve. That long reserve raised an obvious question for a watch you wind by hand: how much is left?

The H-23, announced in September 2025, answers it. Monochrome describes it as a hand-wound caliber "created by ETA exclusively for Hamilton", built on the ETA 2801-2 and belonging to the same Powermatic 80 family as the H-50. What's new is a power reserve display driven by a differential, a small gear arrangement that measures how far the mainspring is wound. Hamilton styled the gauge like a fuel gauge, with F and E and a touch of red, and aBlogtoWatch found it discreet enough not to spoil the dial.

The other change is in the barrel. According to Monochrome, the H-23 uses a slipping spring there, which keeps the gauge in sync after a knock and stops you from overwinding by removing the hard stop at the end of winding. That's the same principle an automatic uses. In July 2026 Hamilton added green and blue dials to the original black and white.

Accuracy in the real world

Hamilton doesn't publish an accuracy figure for the H-23, and the watch is too new for many long-term owner reports. The reviews we found didn't include timing results either. We'd rather say that than guess.

What we can say is that the building blocks are known. The H-50, which shares the same 2801-2 base, 3 Hz beat and Nivachron spring, is widely reported by owners to run within a few seconds a day. The Nivachron spring also protects against the most common cause of a sudden gain, magnetism from laptops, phone cases and bag clasps. There's no obvious reason for the H-23 to behave differently, but that's reasoning, not measurement. If you've timed yours, it's worth logging it for a few weeks before judging.

The gauge helps with consistency in one practical way. Most movements run at their steadiest when well wound. With the H-23 you can see when it's dropping toward E and top it up before the rate starts to wander.

Reliability and servicing

The H-23 is more complex than the H-50 because it adds the differential and the reserve display, but the base underneath is one of Swiss watchmaking's most proven designs. It's too new for any pattern of faults to have shown up, and none has been reported in the reviews.

• Brand service. Like Hamilton's other H-series calibers, it's serviced through Hamilton and Swatch Group service centers, which may exchange the movement rather than rebuild yours.
• Independents. Parts for Swatch Group's modified calibers are restricted, and the power reserve module is specific to this movement. Plan on brand service unless a watchmaker confirms they can get parts.
• Warranty. Hamilton gives a 2-year international warranty.

Quirks worth knowing

• No hard stop. Unlike the H-50 in the Khaki Field Mechanical, the H-23 doesn't lock when full. The slipping spring lets the mainspring slip, so watch the gauge reach F rather than waiting for the crown to resist.
• It still won't wind itself. aBlogtoWatch's reviewer said he'd probably have preferred an automatic in a case this thick. If you want 80 hours with no winding, look at the Khaki Field Auto.
• Lots of turns from empty. An 80-hour mainspring takes much more winding than a 42-hour one. Topping it up each morning is easier than winding from E. See how to wind a mechanical watch.
• Thicker than the Field Mechanical. At about 12 mm, the case is noticeably thicker than the 38 mm Khaki Field Mechanical's 9.5 mm, partly because of the extra module.
• No date, no danger zone. With no date wheel you can set the time at any hour.

How it compares

• Hamilton H-50: same base, same 80 hours, no gauge, thinner watch. The Khaki Field Mechanical is the purer field watch; the Power Reserve is the one that tells you when to wind.
• Hamilton H-10: the 80-hour automatic in the Khaki Field Auto. No winding needed on days you wear it, but no gauge either.
• Powermatic 80: the automatic Tissot relative, with the same 80-hour, 3 Hz formula.
• Nomos Alpha: a finely finished German hand-winder with about 43 hours. It's the prettier movement, but the H-23 gives you nearly twice the running time and a gauge to watch it by.

Living with the 80-hour reserve

The gauge changes how you think about winding. Wind your Khaki Field Power Reserve to F on Friday morning, take it off Friday evening, and it'll still be running on Monday morning, with the hand sitting near E to remind you. Leave it in the drawer until Monday night and it will have stopped.

The gauge only helps while the watch is in front of you, though. If it's in a drawer while you wear a Khaki Field Auto or a diver for the week, you won't see it drop. Watch Winder counts down the 80 hours for each watch you own and reminds you before one stops, so the Power Reserve gets wound before it hits E rather than after. To check a specific gap, try the "Will my watch stop?" calculator.

Verdict

The H-23 takes the H-50's best feature, an 80-hour reserve in a hand-wound field watch, and puts it on the dial where you can see it. That's genuinely useful on a manual-wind watch, and the slipping-spring barrel makes it harder to damage by overwinding. The trade-offs are a thicker case than the classic Khaki Field Mechanical, no published accuracy or jewel count, and too little long-term history to call its reliability proven. If you like winding and want to know exactly when you need to, the Khaki Field Power Reserve is the one to get.

FAQ

How long does the Hamilton Khaki Field Power Reserve run when fully wound?

About 80 hours, a little over three days, from a full wind with the H-23. The gauge at 9 o'clock shows how much is left.

Is the Hamilton Khaki Field Power Reserve automatic?

No. The H-23 is hand-wound only, so wearing it won't wind it. Wind it by the crown until the gauge reads F.

Can you overwind the Khaki Field Power Reserve?

The H-23 has a slipping spring in the barrel, so there's no hard stop and it's designed not to be damaged by overwinding. Once the gauge reads F, further winding does nothing.

What's the difference between the Khaki Field Mechanical and the Khaki Field Power Reserve?

Both are hand-wound with 80 hours of reserve. The Khaki Field Power Reserve adds a reserve gauge and a slipping-spring barrel, in a 40 mm case rated to 100 m.

How accurate is the Hamilton Khaki Field Power Reserve?

Hamilton doesn't publish an accuracy figure, and there are few long-term owner reports yet. Its sister movement, the H-50, is commonly reported to run within a few seconds a day.

How often should I wind my Khaki Field Power Reserve?

Once a day is the easiest routine. With 80 hours in reserve, missing a day or two won't stop it, and the gauge shows when it's getting low.

What is the Hamilton H-23 based on?

The ETA 2801-2 hand-wound movement, reworked with Powermatic 80 technology, a 3 Hz balance, a Nivachron hairspring and a power reserve differential.

Sources

• Hamilton: Khaki Field Mechanical Power Reserve 40mm H69509930
• Monochrome: Introducing the Hamilton Khaki Field Power Reserve Mechanical 40mm
• Monochrome: New green and blue dials for the Hamilton Khaki Field Power Reserve 40mm
• aBlogtoWatch: Watch review, Hamilton Khaki Field Power Reserve

Keeping it running

• Wind it fully once a day, at the same time, until you feel the crown stop. Never force it past that point. Can you overwind it?
• A full wind lasts about 80 hours, so winding every morning keeps it running with time to spare.
• A watch winder can't wind a hand-wound movement, so it needs you instead.
• If it does stop, don't set the date between 9pm and 3am. Check if it's safe.

All Hamilton movements · Other 80-hour movements

Never let it stop

Watch Winder counts down the reserve of every watch you own and reminds you before one stops. It already knows the Hamilton H-23: type your watch's name and the reserve fills itself in.

Manufacturer's published figure. Real reserve varies with the watch's age and service; check your manual.