Zero!
You don’t need real money!
Use the below approaches to start your trading journey before using real money.

1 Use Demo account:
Exchanges, brokers usually allow traders to set up demo accounts to start trading in Stocks, 
Forex, Commodities, Crypto, ETFs, Currencies, Indices, You will be given virtual money to start experimenting!

2 Use TradingView Paper Trading:
TradingView charting tool has a  paper trading feature that you can use to practise your trading skills as a beginner. You will be given 100000 USD fake money.

3 Use Learning to Earn
Crypto exchanges like Coinbase pay you in crypto for watching educational content. Learn to regularly accumulate crypto and use it to participate in crypto trading markets.  

Before you think of putting in real money, use all the above approaches to do at least 50 trades and document your profit /loss and strategies for each of these trades in a journal.

This will help you refine your trading plan based on your trades with fake money first and then you can start trading with real money!