As a simple correction, a flat pattern has two corrective waves (a-wave and b-wave) and an impulsive wave (c-wave). Moreover, the b-wave must retrace more than 61.8% of the a-wave. In other words, the minimum condition for a flat is that the b-wave exceeds 61.8% of the previous a-wave. Once again, the golden ratio plays an important role in the Elliott Waves Theory.

For a pattern with three large swings, there are many types of flats. Elliott looked at the b-waveâ€™s length to split flats into three categories.

## Weak B-Wave

The name refers to the inability of the b-wave to retrace much more than 61.8% of the previous a-wave. In fact, itâ€™ll stop before the 80% retracement level.

Now that we have determined the b-waveâ€™s retracement, the c-waveâ€™s length tells us the type of flat pattern:

• B-failure â€“ the c-wave is longer than the b-wave but no more than 138.2%
• Double failure â€“ the c-wave is shorter than the b-wave
• Elongated flat â€“ the c-wave is longer than 161.8% of the b-wave

## Normal B-Wave

This time the b-wave retraces beyond 80% of the a-wave, but no more than a full retracement. The types of flats in this category are:

• Common â€“ the c-wave is longer than the b-wave but no more than 138.2%
• C-failure â€“ the c-wave is shorter than the b-wave
• Elongated flat â€“ the c-wave is longer than 161.8% of the b-wave

## Strong B-Wave

In this category, the b-wave retraces well beyond the start of the a-wave. The types of flats are:

• Irregular failure â€“ the c-wave is shorter than the b-wave
• Irregular â€“ the c-wave is longer than the b-wave but no more than 138.2%
• Elongated flat â€“ the c-wave is longer than 161.8% of the b-wave

While it may look confusing with all these types of flats, the reason why they are listed like this is to emphasize what they have in common. Namely, the conditions that give the types of flats are similar for all categories; only the b-wave retracement criteria differ!

Letâ€™s play a little game. Name the two types of flat below based on the definitions above:

Remember, the key is the b-waveâ€™s retracement. This will tell you the category. Next, focus on the c-waveâ€™s length, as it will tell you the type of flat.

In the first example, the b-wave retraces between 80% and 100% of the a-wave, and the c-wave slightly exceeds the b-waveâ€™s length. Thatâ€™s a common flat!

On the right side, the b-wave exceeds the a-wave start, and the c-wave is much bigger than 161.8% of the b-wave. Thatâ€™s an elongated flat!

You might say: so what? Well, Elliott established clear rules and places where each flat typically appears. Therefore, if you can correctly identify the type of the flat, it becomes easier to identify the larger wave, or, where you are with the count and what wave to expect next.

## Main Takeaways:

• There are three categories of flat patterns; weak, normal and strong.
• The length of the b-wave indicates the category and the length of the c-wave gives the type.
• A 61.8% retracement is the minimum retracement for the b-wave.
• Flats are the most common of simple corrective waves.