How big is Lake Ontario?
For this comparison, Lake Ontario measures 311 km in length (193.2 mi). Published maximum length, rounded to 311 km.
The same icon style prevents detailed map recognition from becoming a size hint.
Put the measurement in perspective
The recorded length is 50.242 times the height of Denali (6.19 km). This is a ratio of the labelled linear dimensions. It does not describe weight, area or volume.
Use the interactive comparison to see both drawings on one shared scale. You can choose another reference or enter your own height. If the sizes are very far apart, the smaller object may be almost invisible; an intermediate reference makes the progression easier to inspect.
Measurement source
US Environmental Protection Agency or National Park Service
The note above explains the specific value selected. Drawings are schematic; the stated measurement determines the scale. Report a measurement issue.
Check the convention
Maximum length, river-course length and shoreline length are distinct quantities. Our geography drawings are schematic icons rather than cartographic outlines.
Read our methodology for the selection and scoring rules. Practise these dimensions in the geography size guessing game.