Image / Button size not working in tkinter python

Question

So I'm new to Tkinter, and I decide to make my simple calculator nicer using images. So I try to add images for the buttons: (example)

and for some reason with the size, the buttons look like this in the GUI:

and I can't seem to figure out how to change the size of the images. I've already tried using width and length paremeters on the tk.PhotoImage objects and the button() object. Before the images existed, the buttons weren't small. Here's my code:

import tkinter as tk
expression = ''

def press(sym):
  global expression, equation
  expression = expression + str(sym)
  equation.set(expression)

def equalpress():
  global expression, equation
  try: 
    result = str(eval(expression))
    equation.set(result)
  except:
    equation.set('ERROR')
    expression = ''

def clearpress():
  global expression, equation
  equation.set('')
  expression = ''

def main():
  global expression, equation
  print('hi')
  root = tk.Tk()
  root.title('Calculator 1.0')
  root.geometry("360x200")
  equation = tk.StringVar()
  expression_field = tk.Entry(root, textvariable=equation)
  expression_field.grid(columnspan=4, ipadx=70)
  
  photo = tk.PhotoImage(file = r'1_button.png', height=1, width=7)
  button1 = tk.Button(root,image=photo,command=lambda: press(1))
  button1.grid(row=2, column=0)

  photo = tk.PhotoImage(file = r'2_button.png', height=1, width=7)
  button2 = tk.Button(root,image=photo, command=lambda: press(2))
  button2.grid(row=2, column=1)

  photo = tk.PhotoImage(file = r'3_button.png', height=1, width=7)
  button3 = tk.Button(root,image=photo,command=lambda: press(3))
  button3.grid(row=2, column=2)

  photo = tk.PhotoImage(file = r'4_button.png', height=1, width=7)
  button4 = tk.Button(root,image=photo,command=lambda: press(4))
  button4.grid(row=3, column=0)

  photo = tk.PhotoImage(file = r'5_button.png', height=1, width=7)
  button5 = tk.Button(root,image=photo,command=lambda: press(5))
  button5.grid(row=3, column=1)

  photo = tk.PhotoImage(file = r'6_button.png', height=1, width=7)
  button6 = tk.Button(root,image=photo,command=lambda: press(6))
  button6.grid(row=3, column=2)

  photo = tk.PhotoImage(file = r'7_button.png', height=1, width=7)
  button7 = tk.Button(root,image=photo,command=lambda: press(7))
  button7.grid(row=4, column=0)

  photo = tk.PhotoImage(file = r'8_button.png', height=1, width=7)
  button8 = tk.Button(root,image=photo,command=lambda: press(8))
  button8.grid(row=4, column=1)

  photo = tk.PhotoImage(file = r'9_button.png', height=1, width=7)
  button9 = tk.Button(root,image=photo,command=lambda: press(9))
  button9.grid(row=4, column=2)

  photo = tk.PhotoImage(file = r'0_button.png', height=1, width=7)
  button0 = tk.Button(root,image=photo,command=lambda: press(0))
  button0.grid(row=5, column=0)

  photo = tk.PhotoImage(file = r'plus_button.png', height=1, width=7)
  plus = tk.Button(root,image=photo,command=lambda: press("+"))
  plus.grid(row=2, column=3)

  photo = tk.PhotoImage(file = r'minus_button.png', height=1, width=7)
  minus = tk.Button(root,image=photo,command=lambda: press("-"))
  minus.grid(row=3, column=3)

  photo = tk.PhotoImage(file = r'times_button.png', height=1, width=7)
  multiply = tk.Button(root,image=photo,command=lambda: press("*"))
  multiply.grid(row=4, column=3)

  photo = tk.PhotoImage(file = r'divide_button.png', height=1, width=7)
  divide = tk.Button(root, image=photo,command=lambda: press("/"))
  divide.grid(row=5, column=3)

  photo = tk.PhotoImage(file = r'equals_button.png', height=1, width=7)
  equal = tk.Button(root, image=photo,command=equalpress)
  equal.grid(row=5, column=2)

  photo = tk.PhotoImage(file = r'clear_button.png', height=1, width=7)
  clear = tk.Button(root, image=photo,command=clearpress)
  clear.grid(row=5, column='1')

  photo = tk.PhotoImage(file = r'decimal_button.png', height=1, width=7)
  Decimal= tk.Button(root, image=photo,command=lambda: press('.'))
  Decimal.grid(row=6, column=0)


  
  # start the GUI
  root.mainloop()

if __name__ == '__main__':
  main()
else: 
  print('You are not in the right file')

How can I change my button/image size?

(I am also using python 3)