For APA (7th edition) please cite as: Morys-Carter, W. L. (2023, July 4). *ScreenScale* [Computer software]. Pavlovia. https://doi.org/10.17605/OSF.IO/8FHQK The date is the most recent substantial commit on Gitlab. Code available from https://gitlab.pavlovia.org/Wake/screenscale written in PsychoPy version 2023.1.3. Try it: https://run.pavlovia.org/Wake/screenscale/ Credit card image: https://pixabay.com/vectors/bank-buy-card-credit-credit-card-1300155/ or Open Science Tools version by Todd Parsons (2023) To use, add the screen_scale routine to your experiment and then multiply the desired positions and sizes in cm of following stimuli by x_scale and y_scale. https://discourse.psychopy.org/t/how-to-use-screen-scale-routine/21904 It works with norm, pix or height units. https://discourse.psychopy.org/t/scalescreen-cc-screen-dimensions-from-pix-to-norm/20331 Visual angle is trickier to do online because you would also need to know the distance to the screen. https://discourse.psychopy.org/t/can-not-convert-degree-to-pixel-unit/22705 Beware of having a routine prior to screen_scale which ends on a space bar. https://discourse.psychopy.org/t/implementation-of-screenscale-experiment-into-my-own/22850