The cost of a transfer depends on the amount you are sending, your method of payment, and the exchange rate. Wise fees are dependant on three things - the amount being sent, how you pay, and the exchange rate.
The amount you're sending
Wise fees are set as a percentage of the amount you are sending. The percentage varies from currency to currency. The exception to this is if you are sending out a small amount of money, in which case there is a minimum transaction fee.
How you pay
There are different ways to pay depending on the country you are sending from. You'll be able to see how much each payment method or type of transfer costs when you set up your transfer.
You will always get the mid-market rate on exchanges and this is the rate banks use to trade between themselves. The mid-market rate is always moving so be sure to monitor them on the pricing page.
Wise does offer guaranteed rates on certain currencies. Please read more here.