The hour is a pillar, not a footnote
The name Four Pillars includes the hour alongside year, month, and day. Each pillar has a paired stem and branch. Leaving out the hour therefore changes the information available for interpretation; it is not simply leaving one small preference blank.
Traditional hour signs use time ranges rather than a unique sign for every minute. Boundary conventions and recorded local time can matter. That is a reason to be careful with uncertain records, not a reason to guess an exact minute.
If you do not know the time
Check a reliable record or ask family if that is comfortable and possible. If you still do not know, keep the uncertainty visible. Read the known pillars as a partial chart and avoid conclusions that depend on a specific hour.
If you have a range, note whether it crosses a traditional hour boundary. Two candidate times may lead to different hour pillars. Comparing those possibilities is more honest than quietly choosing one.
Use what you have
K Saju Decode allows you to begin a free Saju exploration with the birth details available to you. The guide to Four Pillars readings explains the rest of the chart's structure before you interpret the result.
A note on interpretation
The correct hour pillar depends on the time convention used by the reading method. Do not present an approximate or assumed time as verified birth data.