A little knowledge. A better eye.

Find your perspective.

Understand the measurements behind the silhouettes, learn useful mental rulers, and make your next guess a little sharper.

Build a sense of scale using familiar references, dimension labels and simple ratios. Practical tips for a visual size comparison game.

Understand the dimensions used in size comparison games, including height, body length, width, diameter and mountain elevation.

Read animal size comparisons accurately by checking adult ranges, sex, measurement axes and upper-size records.

Why dinosaur lengths are estimates, how fossil reconstructions affect scale and how to compare a T. rex with a sauropod.

Compare landmark heights accurately by checking whether a measurement includes antennas, spires, pedestals or only the occupied building.

Compare planet diameters on a shared scale and understand why radius, equatorial diameter, area and volume give different ratios.

Learn the transparent SizeGuess score formula: 100 points per round, equal penalties for half and double, and a maximum daily score of 500.

A simple classroom activity for practising estimation, ratio, units and measurement uncertainty with the SizeGuess comparison tool.

Get a sense of scale.