Compare Fonts → Sans Serif → Roboto vs Arimo

Roboto vs Arimo

Both are sans serif faces on Google Fonts. Arimo has the larger x-height, so it looks bigger at the same size. Roboto takes more horizontal space.

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Roboto

Handgloves & Quartz Jockeys

The quick brown fox jumps over the lazy dog. Pack my box with five dozen liquor jugs, then ship it to 1,842 Grove Street by 9:30 AM.

Handgloves & Quartz Jockeys

The quick brown fox jumps over the lazy dog. Pack my box with five dozen liquor jugs, then ship it to 1,842 Grove Street by 9:30 AM.

Measured from the font files. Heights and widths are shown as a share of the font size, so they compare directly at any point size.
Measurement	Roboto	Arimo	Difference
x-heightHeight of lowercase letters, as a share of the font size. Higher reads larger at the same point size.	52.8%	52.8%	0.0%
Cap heightHeight of capitals, as a share of the font size.	71.1%	68.8%	2.3%
x-height to cap ratioProportion of lowercase to uppercase. Higher feels more modern and open.	0.74	0.77	0.03
Stroke weightMeasured thickness of a vertical stroke. Higher is heavier on the page.	9.1%	9.2%	0.2%
Stroke contrastHorizontal stroke divided by vertical. 1.0 is even; below 0.5 means strong thick-thin modulation.	0.82	0.70	0.11
Average character widthMean lowercase advance. Higher takes more horizontal space.	49.9%	48.9%	1.0%

Stroke contrast: Roboto measures 0.82, Arimo measures 0.70. Horizontal stroke divided by vertical. 1.0 is even; below 0.5 means strong thick-thin modulation.
Average character width: Roboto measures 49.9%, Arimo measures 48.9%. Mean lowercase advance. Higher takes more horizontal space.
x-height to cap ratio: Roboto measures 0.74, Arimo measures 0.77. Proportion of lowercase to uppercase. Higher feels more modern and open.