Debuting in 1914, Hamilton’s Khaki Field has maintained its status as one of the most enduring field watches in horology. Built on over a century of battlefield-tested heritage, the Swiss-American brand has largely kept its iconic collection unchanged — and for good reason. That changes now with the introduction of the Khaki Field Power Reserve Mechanical 40mm, marking the first time Hamilton has added a power reserve indicator to its legendary field watch.
Eighty Hours and Counting
The most notable addition to the Khaki Field for 2025 is the fuel gauge-style power reserve indicator positioned at 9 o’clock. To achieve this, Hamilton worked with ETA to develop the exclusive H-23 movement, a hand-wound caliber delivering an impressive 80 hours of autonomy — that’s more than three full days of runtime from a single winding session.
The complication operates through a differential mechanism that relies on friction between internal components. Hamilton is essentially solving the problem of, what happens when a field watch takes a hard knock? The movement incorporates a slipping spring inside the barrel that automatically resynchronizes the power reserve display during winding, eliminating the need for service intervention. Additionally, this spring prevents the crown from hitting a hard stop when fully wound, protecting against overwinding damage.
Keeping What Works
Housed in a 40mm sandblasted stainless steel case — filling the gap between Hamilton’s 38mm and 42mm field watches — the Power Reserve maintains the collection’s signature aesthetic while accommodating the new movement. The dial features classic 24-hour Arabic numerals with Old Radium Super-LumiNova coating for authentic vintage appeal, while the power reserve indicator uses red accents to mark “F” for full and “E” for empty.
Despite the additional complication, Hamilton has kept the design refreshingly uncluttered. The “Power Reserve 80 Hours” text at 6 o’clock serves as both specification and promise, while the familiar military-inspired layout remains intact.
Available with either black or white dials, the watch comes with either a green NATO strap with brown leather loops, or a three-row stainless steel bracelet.
Spec Sheet
Case Size: 40mm
Case Thickness: 11.95mm
Case Material: Stainless steel
Movement: Hamilton H-23 (ETA exclusive) manual
Power Reserve: 80 hours with on-dial indicator
Crystal: Sapphire with anti-reflective coating
Water Resistance: 50m
Dial Options: Black or white with red power reserve accents
Straps: Green NATO with brown leather loops or three-row steel bracelet
Pricing & Availability
The Hamilton Khaki Field Power Reserve Mechanical 40mm is available now, priced at $945 on NATO strap or $1,025 on the steel bracelet.
Recap
Hamilton Khaki Field Power Reserve
Hamilton introduces its first Khaki Field with a power reserve indicator, featuring an exclusive ETA-developed H-23 movement that delivers 80 hours of runtime displayed via a fuel gauge-style complication at 9 o’clock.
