How to calculate memory allocated in rdkafka producer?

I want to implement some Kafka producers using librdkafka each one has huge traffic and many topics. Before that, I want to calculate how much RAM I need. I know that there are some options that affect this calculation like queue.buffering.max.messages, queue.buffering.max.kbytes and message.max.bytes and also the number of topics and partitions. So how can I calculate the allocated RAM or at least the maximum memory I need?