Metric vs Imperial Revit Families: What you need to know
Umberto RinaldiShare
If you've ever downloaded a Revit family and found that dimensions looked wrong in your project, the cause is almost always a metric/imperial mismatch. Here's what the difference actually means, why it matters, and how to avoid the problem entirely.
Metric vs Imperial in Revit: The Core Difference
Revit families are authored in a specific unit system — either metric (millimeters, centimeters, meters) or imperial (inches, feet). This affects:
- Default parameter values — a desk width of "1800" means 1800mm in a metric family, but would be nonsensical in imperial
- Dimension snapping and placement — families authored in the wrong unit system can place at unexpected scales
- Template compatibility — metric project templates and imperial project templates handle family units differently
Revit can convert units at the project level, but a family authored in imperial and loaded into a metric project (or vice versa) will often require manual parameter adjustment to display correctly. This is a known friction point, especially when mixing families from different sources.
Can You Use a Metric Family in an Imperial Project (and Vice Versa)?
Technically yes — Revit will load the family regardless of unit system. But in practice:
- Parameter values won't auto-convert — a "Width" parameter set to 900 in a metric family stays 900 when loaded into an imperial project. Revit doesn't know if that's 900mm or 900 inches
- Nested families can compound the problem — if a parametric family contains nested components, unit mismatches can cascade
- Schedules and tags will show incorrect values — any schedule pulling dimensions from a mixed-unit family will produce unreliable data
The safest workflow is always to use families authored in the same unit system as your project template.
Dual-Format Families: The Clean Solution
The cleanest solution to the metric/imperial problem is using families that ship in both formats — separate .rfa files for metric and imperial, authored natively in each unit system, not converted.
Conversion (metric-to-imperial or vice versa) introduces rounding errors and parameter drift. Native authoring in both systems means the family behaves correctly in either project type from the moment you load it.
How Factory268 Handles Metric and Imperial
Every Factory268 pack includes both metric and imperial .rfa files, authored natively — not converted. Each download contains:
/metric/ folder — families in millimeters, compatible with metric project templates (EU, UK, most international markets)
/imperial/ folder — families in feet and inches, compatible with imperial project templates (US, Canada)
A .rvt showroom file (metric) for previewing all families before loading
This means you buy once and use in either project type. No separate SKU for metric vs imperial, no conversion workflow, no parameter drift.
Which Unit System Should You Use?
| Context |
Recommended unit system |
| EU / UK / Australia / most international | Metric (mm) |
| USA / Canada | Imperial (feet/inches) |
| International firm with mixed projects | Both — use dual-format families |
| BIM execution plan specifies units | Follow the BEP |
If you're working in a firm that handles both EU and US projects, dual-format families are not a convenience — they're a requirement.
Explore the Full Factory268 Catalog
Every pack in the Factory268 catalog ships with both metric and imperial formats included. Browse by room type or collection to find the families your project needs.
👉 Explore the Factory268 Catalog