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About this tool
Geometric sans pairings with a grid-snapped UI type scale, mono face for numbers and a slide legibility check.
Tech Startup Font Pairing builds a complete product type system from a geometric or neo-grotesque Google Font trio: a display face, a UI text face and a monospace for numbers and code. Sizes come from a modular scale (size = base × ratio^step) and are then snapped to your 4px or 8px baseline grid, with line boxes rounded to the same grid so cards, tables and buttons stack cleanly. It also converts the same type onto a 16:9 slide and checks it against the 20-arcminute character height that ISO 9241-303 associates with comfortable reading.
Open Tech Startup Font Pairing on AltFTool — it loads instantly in your browser.
Add your input to the workspace.
Adjust the options until the result looks right.
Copy or download the output and put it to work.
Font sizes and line boxes are snapped to your baseline grid, and collapsed steps are flagged instead of hidden.
Each pairing names a monospace for metrics, IDs and code, with tabular figures in the generated CSS.
Minimum slide size is derived from viewing distance, screen height and character height, not from a rule of thumb.
16px is the common floor for UI body text because it is the browser default root size and stays readable without zoom on a phone. Below about 14px, long-form reading becomes tiring; labels and captions can sit at 12–13px if they are short and high contrast.
Because a modular scale produces awkward values like 39.06px, and unsnapped line boxes stop components lining up. Snapping each size and its line box to a 4px or 8px multiple keeps cards, list rows and buttons on the same rhythm — at the cost of a small drift from the pure ratio, which this tool shows for every step.
Size it by angle, not by a fixed point size: a character should subtend about 20 minutes of arc at the back row. On a 1.5 m tall screen viewed from 8 m that works out to roughly a 48px font on a 1920×1080 artboard. Halve the distance and you can halve the size.
Yes, if the family has enough weight range. A single variable family such as Manrope or Inter set at 400 for text and 700–800 for headings gives clear hierarchy, loads one font file instead of two or three, and removes any risk of a mismatched x-height between the two faces.