The present invention provides systems, methods, and standards for calibrating nano-measuring devices. Calibration standards of the invention include carbon nanotubes and methods of the invention involve scanning carbon nanotubes using nano-scale measuring devices. The widths of the carbon nanotube calibration standards are known with a high degree of accuracy. The invention allows calibration of a wide variety of nano-scale measuring devices, taking into account many, and in some cases all, of the systematic errors that may affect a nano-scale measurement. The invention may be used to accurately calibrate line width, line height, and trench width measurements and may be used to precisely characterize both scanning probe microscope tips and electron microscope beams.