title: keras model.fit with validation data - which batch_size is used to evaluate the validation data?
body: <p>I want to validate my model with validation data inside </p>
  
  <pre><code>model.fit(x_train, y_train, batch_size= 50, epochs=1,validation_data=(x_test,y_test))
  </code></pre>
  
  <p>Now, I want to train with batch_size=50. My validation data x_test is like of length of 1000. 
  As I can read from the doc the validation data is used after each epoch to evaluate. So I assume the model.evaluate method is used? But what batch size is used?</p>
  
  <p>My validation data is greater then the batch_size in the fit method.</p>
  
  <p>How is this handled?</p>
  
  <p>What are the result if just the training batch_size is used but validation data is larger? Is val_acc averaged over each batch?</p>
  
  <p>I want to validate on all my data in one batch.</p>