Bhav (House) and Rasi (Sign) are two different things in astrology. They are independent of each other.

Here is the one picture where you can look at both the Rasi (Left) and Bhav (Right) chart.
Rasi Chart - This chart shows the position of the planet in 12 Rashis at the time of birth and the starting point is calculating by knowing the rising sign in the eastern horizon.

Bhav Chart - This chart shows the placement of planets in different houses at the time of birth. The first Bhav is calculated from the degree at which the sign is arising in the eastern horizon at birth time.

For example - In the above case Taurus was the first sign on the eastern horizon. The Taurus would be the Lagna at the time of birth.

In Rashi Chart, the remaining sign will follow after Taurus and placement of planets will be marked in the remaining house.

But in the Bhav Chart, the degree of Taurus is 20.42 degrees. This is the midpoint of the first house and each house is of 30 degrees. The start and end of the first house will begin 5-degrees Taurus to 5-degrees Gemini. The second house will begin from 5-degree Gemini to 5 degrees Cancer and so on…

You can see that the second house is starting from 5-degrees Gemini and touching to 5-degree Cancer.

In Rasi Chart, Jupiter is in Cancer at 2.54 degree and so it gets moved to 2nd house in Bhav Chart.

There are many systems for Bhav Calculation

Bhav Equal - This is mostly used in the Parashari system with the midpoint.
Shri Pati - This is based on Placidius System and used in KP
Starting Point - This is used in western astrology.

Author's Bio: 

The author is an eminent in astrology and a full-time astrologer in India.