public static long calculateHexDumpTotalChars(final long byteCount) {
        final long completeLines = (long) (((double) byteCount) / HexDump.MAX_BYTES_PER_LINE);
        final long remainingBytes = byteCount % HexDump.MAX_BYTES_PER_LINE;
        return (completeLines * HexDump.MAX_CHARS_PER_DUMP_LINE) + remainingBytes;
    }
The size in chars of a rendered hex dump for byteCount input bytes.
stroom-util/src/main/java/stroom/util/string/HexDumpUtil.java