What's the cheapest way to convert USD into CAD?

Hi,

So I have a RBC USD account in Canada but when I try to send USD, they don't allow sending it using interac. Can this be done?

If not, I checked the conversion rates of RBC and it's pretty bad.

So for $19000 USD, I get these:

RBC: $23820 CAD
TransferWise: $24257 CAD
Google: $24367 CAD

TW quotes $83 USD as fee, so I guess that's why it differs by that much from google?

So should I use TW to do the conversion? If so, then I will have to get the USD into TW, convert it to CAD and then back to RBC.


Thanks in advance.