how much is 9.8 billion robux in usd

9.8 billion Robux is about $122.5 million USD at the common purchase rate of $0.0125 per Robux.

If you mean the DevEx cash-out rate for developers, it would be about $34.3 million USD at $0.0035 per Robux.

Quick math

• Buy rate: 9.8 billion×0.0125=122.5 million9.8\text{ billion}\times 0.0125=122.5\text{ million}9.8 billion×0.0125=122.5 million USD.

• DevEx rate: 9.8 billion×0.0035=34.3 million9.8\text{ billion}\times 0.0035=34.3\text{ million}9.8 billion×0.0035=34.3 million USD.

In plain words

• Player value: roughly $122.5M
• Developer payout value: roughly $34.3M

TL;DR

9.8 billion Robux is about $122.5 million USD to buy, or about $34.3 million USD via DevEx.