Maximum Lot Size one could (theoretically) trade with Oanda?

Not that I would ever be able to do that, but let's just imagine I have an account with about 500 zillion dollars or something like that.

Is there a max lot size one can reach per trade? Like is it limited to a certain number or could I theoretically open a 100 lots-sized trade?

You can simply check the contract specifiactions for each product of your broker.

Either on their website or directly via MT4 (use specification in the market watch window by right clicking on the desired product). Here the min and max lotsize is noted.

Wow, thank you Drolph, didn't know about this yet. Good to know

In case you want to open even higher positions simply click the buy/sell button twice.