Looking on the internet deeply has found these results:

keep calm is the most popular phrase on the web.

be calm 1652,000 results on the web	keep calm 123,500,000 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
Don't tell me to be calm, pony boy. Get out there and just be calm. ECR member Tadeusz Cymański hoped the presidency will be calm and peaceful. I'm a wreck and I have to be calm when Sam gets home. I tend to be calm, things tend to slowdown. And the man cradled his head and told him to be calm. You need to be calm and peaceful. You've been telling me to be calm this whole time.	Arne, if we keep calm, it'll be all right. The main thing is to keep calm. All we need to do is keep calm and we'll find a way out. Try to keep calm, everyone. Let's keep calm here. It's a win. First of all, I am going to try and persuade the Rwandans and the Congolese to keep calm and not to act in haste and risk reopening a conflict when the transition process is in full swing. You've got to keep calm, woman. You should sit down, try to keep calm.

be calm

1652,000 results on the web

keep calm

123,500,000 results on the web

More popular!

Arne, if we keep calm, it'll be all right.
The main thing is to keep calm.
All we need to do is keep calm and we'll find a way out.
Try to keep calm, everyone.
Let's keep calm here. It's a win.
First of all, I am going to try and persuade the Rwandans and the Congolese to keep calm and not to act in haste and risk reopening a conflict when the transition process is in full swing.
You've got to keep calm, woman.
You should sit down, try to keep calm.