The basic steps for most Casio models

To change the time on a Casio watch, press and hold the button labeled Mode or Adjust until the display shows the time-setting screen — usually marked by a blinking hour or minute field. Use the + button to increase the numbers and the − button to decrease them. Move between hours, minutes, and seconds by pressing Mode or a navigation button. Once the time is correct, press Mode again to save and exit.

The exact button names and sequence vary by model line. Casio makes digital watches, analog watches with digital displays, G-Shock models, and solar-powered variants, and each family has slightly different controls. If you have the original manual, that is the fastest reference — the time-setting steps are always in the first few pages. If you no longer have the manual, the model number printed on the back of the watch will let you find the instructions online.

Most Casio watches use a 24-hour military time format by default, though some models let you switch to 12-hour AM/PM display. Check whether your watch is showing the correct hour format before you assume the time is wrong.

Key Takeaways

  • Press and hold Mode or Adjust until the time display starts blinking, then use + and − buttons to change hours and minutes.
  • The exact button sequence depends on your specific Casio model, so check the manual or search for your model number online if the basic steps do not work.
  • Some Casio watches display time in 24-hour format by default; make sure you are not confusing military time with a wrong setting.
  • If buttons do not respond, the battery may be low or dead — a replacement battery usually costs $5 to $15 at a watch repair shop or pharmacy.

Finding your model number and manual

The model number is printed on the back case of your watch, usually as a code like A158W, F-91W, or GW-M5610. Write this number down or take a photo. Search for "[model number] manual" on Google or visit Casio's official support site, where you can download the PDF instruction booklet for free.

Casio's manual PDFs include diagrams showing which button is which and the exact sequence for time-setting on your model. They are usually only a few pages long and cover battery replacement, water resistance limits, and other basic functions. If the PDF does not open or you cannot find your model, try searching "[model number] how to set time" on YouTube — many users have posted video walkthroughs for popular models.

Differences between Casio watch types

Digital watches (like the F-91W or A158W) use the Mode button to cycle through different screens. Hold Mode until you see the hour field blink, then use + and − to adjust. Press Mode to move to minutes, then seconds, then press Mode again to save.

G-Shock models often have four buttons arranged around the face. The sequence is usually: hold the Adjust button (often on the lower left) until the time screen appears, use the + button to increase values, press the Mode or navigation button to move between fields, and hold Adjust again to save. Some G-Shock models have a separate time zone or world time feature that must be set first.

Analog watches with digital displays (like the AQ series) may require you to pull the crown (the knob on the side) outward to one or two positions before the time-setting mode activates. The exact procedure varies widely in this category.

Solar-powered and radio-controlled Casio watches may automatically sync to the correct time if they receive a radio signal or have enough sunlight. If automatic sync is on, manual time-setting may be overridden. Check your manual for how to disable auto-sync if you need to set the time manually.

What to do if the buttons do not respond

If pressing Mode or Adjust does nothing, the battery is likely dead or too weak to power the watch. Casio watch batteries typically last two to seven years depending on model and usage. A dead battery is the most common reason a watch stops responding to button presses.

You can replace the battery yourself if you are comfortable opening the watch case — replacement batteries cost $3 to $8 and are available at pharmacies, drugstores, and online retailers. Search for your model number plus "battery replacement" to find the correct battery type (usually SR626SW, SR927SW, or similar). If you prefer not to open the watch, a watch repair shop or jeweler can replace it for $10 to $25 including labor.

If the battery is new and buttons still do not work, the watch may have water damage or an internal circuit failure. In that case, repair is usually not worth the cost of a new watch, especially for basic digital models under $50.

Adjusting for daylight saving time and time zones

When daylight saving time begins or ends, you only need to change the hour by one. Follow the same time-setting steps as above, but use the + or − button to move the hour forward or backward by one only.

If you travel across time zones, you can change the hour to match your new location. Some Casio models (particularly the AQ and higher-end digital lines) have a separate time zone or world time feature that lets you store two or three different times at once. Check your manual to see whether your model has this feature — if it does, you can set a home time zone and a travel time zone without losing either one.

Resetting the watch to factory settings

If you have changed settings and the watch is now behaving strangely — showing the wrong time format, displaying 24-hour time when you want 12-hour, or cycling through menus unexpectedly — you may need to reset it. Most Casio watches have a reset function, but the button sequence varies by model.

The reset is usually triggered by holding down a specific button (often Adjust or Mode) for 10 to 15 seconds while the watch is in time-setting mode. Resetting erases any custom settings and returns the watch to the state it was in when it left the factory. Check your manual for the exact reset procedure for your model, because pressing the wrong button for too long can sometimes lock the watch or trigger other functions.

Frequently Asked Questions

Why does my Casio watch show 24-hour time instead of 12-hour time?

Your watch is set to 24-hour military time format. Enter time-setting mode and look for a button or menu option to toggle between 24-hour and 12-hour display. The exact method depends on your model — check your manual or search your model number plus "12-hour format" to find the switch.

Can I change the time if the watch is waterproof?

Yes. Waterproofing does not prevent you from using the buttons. Press the buttons normally — waterproofing only protects against water entering through the case seams, not through the button mechanisms. If your watch is rated for diving (usually 100 meters or more), the buttons are sealed and will work fine.

What if I lose the manual and cannot find my model number online?

Try the basic sequence: hold Mode until the display blinks, use + and − to change the time, and press Mode to move between fields. This works for most Casio digital watches. If that does not work, contact Casio customer service with your model number and they can email you the manual or walk you through the steps.

Does changing the time drain the battery faster?

No. Changing the time uses very little power and does not noticeably affect battery life. Battery life is determined by how often the watch runs the display and beeper, not by time adjustments.

Can I set the seconds to zero, or only hours and minutes?

Most Casio watches let you set seconds as well as hours and minutes. In time-setting mode, press Mode to cycle through hour, minute, and second fields. Some basic models skip the seconds field, but most allow you to set it to 00 if you want the watch to start on an exact minute.