Casio BM-500 is a digital wristwatch released in the early 1990s. It used module 943 and offered a barometer, an altimeter and a depth meter. The watch has an analog-digital display with colored scales and a blue bar graph that shows pressure, altitude or depth depending on the mode. Casio designed the BM-500 as a small weather and measurement tool on the wrist.
The BM-500 followed the BM-100 and kept the full sensor set that the BM-200 no longer used. It has a side pressure sensor and a multicolor dial layout that feels like a measurement instrument rather than a simple digital display. Many users wore this watch during diving, caving and outdoor navigation, and the model gained a strong nostalgic reputation for durability. Today the BM-500 appears as a rare and collectible barometric Casio from the early sensor era.
Casio BM-500 – Technical Data
| Field | Data |
|---|---|
| Model | Casio BM-500 |
| Module | 943 |
| Battery | 2× SR927SW (395 equivalent) |
| Manual | Casio BM-500 Manual |
| Glass Type | No confirmed info (If you know please let me know😉 ) |
| Strap Size | 20 mm (lug) / 25 mm (case) |
| Case Material | Resin, side-mounted pressure sensor |
| Functions | Barometer, tendency trend, altimeter, depth meter, 3 alarms, timer, stopwatch, 12/24 h, LED, 100 m WR |
| Production Years | Early 1990s, examples purchased 1992–1993 |
What color versions of Casio BM-500 exist?
The Casio BM-500 was released in a single color version. All watches share the same black case, black strap and multicolor analog-digital dial. Because there is only one version, condition of the text, scales and sensor becomes the main factor for collectors.
1. BM-500 Black Version with Red Lettering (only version)
• Black resin case and black strap
• Black bezel with red BAROMETER and red WEATHER STATION text
• Silver metal side buttons
• Multicolor scale around the dial (blue, green, red)
• Blue bar graph in the upper display segment
• White function labels: ADJUST, MODE, LIGHT, TENDENCY
About the Casio BM-500 sensor system
The Casio BM-500 uses a single pressure sensor placed on the side of the case. This sensor controls the barometer, altimeter and depth meter. It continues the idea from the BM-100 but uses a different layout and a more advanced display.
The pressure sensor reads atmospheric pressure for the barometer and trend modes. It also measures hydrostatic pressure underwater, which allows the watch to show depth. Many users reported good accuracy during recreational diving. The altimeter works in the same way, using pressure changes to calculate height.
The dial of the BM-500 is built around color-coded scales. The blue bar graph acts like an analog needle and changes depending on the mode. It shows pressure, altitude or depth. The colored outer and inner rings help interpret each reading. This design gives the watch its recognizable instrument-style display.
The sensor requires correct calibration and can drift with temperature. Users also noted that the sensor connection depends on tiny springs inside the case. These springs are easy to lose during service. Because the BM-500 is more than 30 years old, many surviving units need careful cleaning and testing after a battery change.
Functions of the Casio BM-500
The Casio BM-500 offers a full set of outdoor and timekeeping functions built around its pressure sensor. It is one of the few Casio models that combines barometer, altimeter and depth meter in a single watch.
Time mode
• Standard time display
• Date and weekday
• 12/24-hour format
• Small trend indicator on the dial
Barometer
• Measures atmospheric pressure in millibars
• Color scales and the blue bar graph show pressure changes
• Useful for short-term weather checks
Pressure tendency
• Reads pressure every few hours
• Up and down arrows show the trend
• Middle bars indicate stable conditions
Altimeter
• Uses pressure changes to show altitude
• Works best in calm weather
• Can be manually reset at any known height
Depth meter
• Uses hydrostatic pressure to measure depth
• Green scale helps read depth in feet
• Confirmed by users to be accurate for recreational diving
Alarms and signal
• Three alarms
• Hourly time signal
• Simple and fast to operate
Timer and stopwatch
• Basic countdown timer
• 1/100 stopwatch
• The bar graph and scales move depending on the mode
Light
• Small LED
• Enough for low-light reading
Water resistance
• Rated to 100 m, suitable for swimming and shallow diving
Production years and model background
The Casio BM-500 comes from the early 1990s, with many confirmed examples purchased new in 1992–1993. It is described in community sources as the second barometric Casio, following the BM-100. The BM-500 kept the full sensor set, including the depth meter, which makes it one of the most complete early sensor watches from Casio.
Casio designed the BM-500 as a compact weather and measurement tool. It uses a side-mounted pressure sensor, a multicolor analog-digital dial and a blue bar graph to show pressure, altitude or depth. This layout was unusual for the time and gave the watch its instrument-like look.
Many users wore the BM-500 in real outdoor environments. They reported long-term use during scuba diving, caving, orienteering, and even on oil platforms. Despite scratches and cosmetic wear, the sensor often stayed functional for many years. These stories helped build the strong nostalgic reputation of the model.
Servicing the BM-500 can be challenging today. Battery leaks damaged many modules over the years. The watch uses tiny springs to connect the sensor to the case, and these can fall out during disassembly. The flex cable and the pads near the crystal are also sensitive after decades of use. Because of this, working BM-500 units are less common than they once were.
Today the BM-500 is seen as a rare and historically important barometric Casio. It represents one of the last full-sensor designs before the BM line moved toward simpler trekking functions.
Other BM watches and model evolution
• BM-100 (1989) – first Casio barometer. Full sensor set: barometer, altimeter, depth meter.
• BM-200 (1991–1992) – successor with trekking focus. No depth meter. Mask-style case.
• BM-500 (early 90s) – full-sensor branch. Same functions as BM-100 in an analog-digital layout.
• BM-600 / BM-610 (1995) – last generation. Barometer + altimeter. Early ProTrek-style design.
BM-500 stands on the full-sensor branch, while BM-200 and BM-600 continue the simplified trekking path.
Summary
The Casio BM-500 is one of the most complete sensor watches from the early 1990s. It offers a barometer, altimeter and depth meter, all supported by a side pressure sensor and a unique analog-digital display with colored scales. The blue bar graph, the multicolor rings and the compact resin case create a layout that feels like a small wrist-mounted instrument.
Collectors value the BM-500 for its full sensor set, long-term durability and strong nostalgic history. Many original owners used this model during diving, caving and outdoor navigation, which shows how capable it was in real conditions. Surviving examples are less common today because battery leaks and aging parts damaged many modules. Working units with clean scales and a stable sensor are considered rare and desirable pieces of Casio’s early weather-sensor era.
FAQ – Casio BM-500
Does the Casio BM-500 have a depth meter?
Yes. The BM-500 has a full sensor set with a barometer, altimeter and depth meter. It is one of the few Casio watches that include all three functions.
How accurate is the depth reading on the BM-500?
The depth meter uses hydrostatic pressure, and users report good accuracy for recreational diving and snorkeling. Calibration and stable conditions improve the reading.
Which strap fits the Casio BM-500?
he BM-500 uses a 20 mm lug width and a 25 mm case connection. Original straps are difficult to find. Some collectors adapt straps from similar early-90s Casio models.
Is Casio BM-500 rare today?
Yes. Many units were damaged by battery leaks or broken sensor connections. Working examples with clean displays and intact colored scales are considered rare.
Daniel is the person behind Vintage Casio Restore, a project dedicated to restoring and documenting vintage Casio digital watches from the 80s and 90s. Based in Poland, he combines technical precision with a passion for retro design, bringing forgotten models back to life and sharing their stories online.
Outside the workshop, Daniel works in a digital agency, managing SEO and content strategy for technology clients, blending his professional experience with his love for classic tech and design.
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