diff --git a/pytorch_lightning/core/lightning.py b/pytorch_lightning/core/lightning.py
index c33297934eed1..55b66f94b7a3c 100644
--- a/pytorch_lightning/core/lightning.py
+++ b/pytorch_lightning/core/lightning.py
@@ -1387,7 +1387,7 @@ def get_progress_bar_dict(self):
             if running_train_loss is not None
             else float("NaN")
         )
-        tqdm_dict = {"loss": "{:.3f}".format(avg_training_loss)}
+        tqdm_dict = {"loss": "{:.3g}".format(avg_training_loss)}
 
         if self.trainer.truncated_bptt_steps is not None:
             tqdm_dict["split_idx"] = self.trainer.split_idx