Calculate the Output size in Convolution layer

Question

What will be the output size, if the input to convolution layer of neural network is an image of size 128X128X3 and 40 filters of size 5X5 are applied to it?

Answer 1

Formula : n[i]=(n[i-1]−f[i]+2p[i])/s[i]+1

where,

n[i-1]=128

f[i]=5

p[i]=0

s[i]=1

so,

n[i]=(128-5+0)/1+1 =124

so the size of the output layer is: 124x124x40 Where '40' is the number of filters