Direct answer
A forex 4-hour candle starts at the beginning of each 4-hour time block in your chart. In practice, that means the candle’s open time is aligned to fixed clock boundaries (for example, 00:00, 04:00, 08:00, etc.), rather than starting when price reaches a specific level.
Explanation: how a 4-hour candle “starts”
A candlestick groups price movement into a defined time interval. For a 4-hour (H4) candle, the interval length is four hours. The “start” of the candle is the timestamp at which that four-hour interval begins, and the candle’s open price is recorded at that start time.
Two details control the exact displayed start time:
- The chart’s time zone / server time basis. Platforms often render candles according to a chosen or default time basis. If your time zone setting differs, the candle boundaries you see can shift.
- The platform’s alignment rule. Even with a 4-hour interval, the platform decides how to map those intervals onto the clock (the first boundary of a day, and then every four hours after that).
A useful way to think about it: the candle is not a “live event” triggered by bearish or bullish movement. It is a time-boxed record that aggregates the open, high, low, and close within its four-hour window.
Example checks you can do
- Check the open timestamp on a single candle. Select an H4 candle and look at its time label. The candle start should match the chart’s 4-hour boundary pattern.
- Compare around a known boundary. If one candle closes at a boundary (e.g., end of a four-hour block), the next candle should open immediately at the next boundary.
- Change chart time zone and re-check. If the platform offers a time zone or server time setting, you can verify whether the H4 candle start times shift while the interval length remains four hours.
Limitations and what cannot be assumed
- No universal “one true second.” There isn’t a single start time that applies to every user on every platform. The displayed start depends on your chart’s time basis and alignment.
- No prediction from past candles. Candle timing describes historical grouping; it does not imply future price behavior.
- Uncertainty across platforms. Two charts showing the “same market” can display different candle start timestamps if their time basis differs.
If you want to make your own timing verification reproducible, keep the candle interval (H4) the same and verify the chart’s time zone/server time setting before comparing candle starts.