how do reserve bank decide how much money to be printed?

Central banks, such as a reserve bank, typically use a variety of monetary policy tools to control the money supply and manage inflation. One of the main tools used is setting interest rates. The reserve bank can raise or lower interest rates, which in turn affects borrowing and spending.

Another tool is the open market operations. Central banks buy or sell government securities on the open market, which can increase or decrease the money supply. When the bank buys securities, it is injecting money into the economy, and when it sells securities, it is removing money from the economy.

Another tool is Reserve Ratio Requirement, a policy used by central banks to control the money supply by setting a percentage of deposits that banks must hold in reserve. This can affect the amount of money that banks can lend and ultimately the money supply in the economy.

The decision of how much to print is influenced by several factors such as inflation rate, GDP, Employment rate, balance of trade, foreign exchange rate and so on. The central bank's goal is to maintain price stability and support sustainable economic growth, and the amount of money printed is decided based on the above factors and the central bank's monetary policy goals.