今日何時ぐらいにジムに来るの？って英語でなんて言うの？

You can use both examples on the phone or by text. It is important that you specify the day that you are asking about. Is it today, tomorrow or next week? Also, it is also good to let them know that you are also planning to go and when you plan to go.

You can use both examples on text or on the phone.

"What time" you want to know the time that your friend will be at the gym. "Are you going" you are confirming whether your friend is going to the gym or not. "today" meaning the present day A : What time will you be at the gym today? B : I will be there at 5. A : See you then! C : Are you going to the gym today? D : Yes, I'll meet you there at 6? C : Okay, I will be there!

"When are you going to the gym?" is more straight forward and casual. The second expression is just more specific.

"What time" and "When" both refer to asking about time. I am going to the gym today, will you be going? tells them you are going and asks if they are planning on going today. I am going to the gym today, what time will you be going? this tells them to go to the gym and asks what time they will be going.

1. This is using the present continuous form for making a future arrangement. This may be used any time you want to talk about something such as a booking in your diary for the coming days, months or years. "What are you doing at 3pm on the 24th July?" "Well, I'm working until 2:45pm, so I should be able to meet you about 3pm...but may be a couple of minutes late if the traffic's bad." "OK, I'll see you then!" 2. This is a contracted message for sending a quick text.

"What time will you be at the gym." asks when a person will be at the gym.