When you want an all-sans system, the body font has to differ enough from the heading to create hierarchy — and that's exactly what Source Sans does. It's a humanist sans, so against Montserrat's geometric construction t...
How Montserrat and Source Sans 3 score across four checks — class contrast, role clarity, x-height harmony and mood affinity. Higher is better.
COMPOSITE MATCH
81/100
Reliable choice
Class contrast74
Role clarity84
X-height harmony80
Mood affinity88
WHY IT WORKS
Structure meets readability
When you want an all-sans system, the body font has to differ enough from the heading to create hierarchy — and that's exactly what Source Sans does. It's a humanist sans, so against Montserrat's geometric construction there's real structural contrast: Montserrat leads with geometric strength, Source Sans recedes as calm, narrow, neutral text. That humanist-vs-geometric difference is what keeps it from looking like 'two sans-serifs by accident.'
Where it shines
SaaS, tech, and app marketing where a clean sans-only system reads modern and uncluttered.
Where to be careful
Don't set Source Sans too close to Montserrat in weight — keep headings at 600+ and body at 400 so the two roles stay distinct.