For my both own convenience and to help your understanding of art material cost, I have broken down a convenient chart of canvas sizes and costs:

    Deep Frame Canvases (1½ inches deep)

    inches – USD

  • 12X24 – 26
  • 12X36 – 30
  • 15X30 – 37
  • 16X20 – 27
  • 16X40 – 48
  • 18X24 – 30
  • 20X20 – 28
  • 20X24 – 38
  • 24X24 – 40
  • 24X30 – 50
  • 24X36 – 55
  • 24X48 – 60
  • 30X40 – 65
  • 30X48 – 75
  • 36X36 – 70
  • 36X48 – 80
  • 48X48 – 90
  • 48X60 – 100

and for smaller sizes:

  • 4X4 – 6
  • 5X5 – 8
  • 5X7 – 9
  • 6X6 – 10
  • 8X8 – 12
  • 8X10 – 13
  • 9X12 – 16
  • 10X10 – 15
  • 10X20 – 25
  • 11X14 – 23
  • 12X12 – 20
  • 12X16 – 24

The prices for high grade art supplies listed above are approximate, and do not include sales tax. The list is to help people not only understand the cost of materials, but also for a convenient reference of available sizes.