log4j with timestamp per log entry

A extract from my properties file

log4j.rootLogger=INFO, stdout, logfile

log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d %p (%t) [%c] - %m%n

log4j.appender.logfile=org.apache.log4j.RollingFileAppender
log4j.appender.logfile.File=C:/log/client.log
log4j.appender.logfile.MaxFileSize=5MB
log4j.appender.logfile.MaxBackupIndex=0
log4j.appender.logfile.layout=org.apache.log4j.PatternLayout
log4j.appender.logfile.layout.ConversionPattern=%d %p [%c] - %m%n

Use %d in your PatternLayout.

Also %d can take a format pattern as in %d{dd MMM yyyy HH:mm:ss,SSS} you can pick and choose the elements that you want. When the format pattern is omitted the date will be in ISO8601 format.