From pages like this https://estimatefee.com/ or this https://ethgasstation.info/ we can check in real-time how much is the commission we must pay to the miners for the validation of payments through the Blockchain.
It is important to know that the figure is variable, it is NOT a percentage. The value depends on the bytes transmitted, and at times with more traffic on the network is when the cost of the commission rises the most.
Don't forget that the sender of the cryptocurrency can choose the priority of shipment and depend on the chosen one, the price to be paid for this commission may vary. The higher the speed/urgency, the higher the price of the commission. Special care should be taken when choosing a low priority because, even if the commissions are lowered, the sending can be delayed for a long time.
It is also a good choice to activate, whenever you can, the RBF (Replace by fee) option so that, if you need to, you can change the mining fee.