Updated July 2026: To change units in Revit, go to Manage tab > Settings panel > Project Units, select the discipline, click the value in the Format column, then choose the unit, rounding, and unit symbol. This changes how measurements display in the project, including common values such as length, area, volume, angle, slope, and currency.
If a dimension, tag, schedule, family label, or imported CAD file still shows the wrong unit, Project Units is only the first place to check. Many Revit annotations can override project units at the type, label, schedule field, or import setting level.
Quick answer: Go to Manage > Project Units, click the unit format you want to change, choose Millimeters, Meters, Feet and Fractional Inches, or another unit, set rounding and symbols, then click OK.
For dimensions or tags that do not follow the project setting, select the dimension type or edit the tag family label and either turn on Use project settings or set a custom Units Format.
Where Units Change in Revit
Revit units are display settings, not a single global switch that rewrites every name, family, tag, and imported file in the model. That is why a project can use millimeters for length, square meters for area, feet and inches for a special dimension type, and a custom format inside one tag family.
| What you need to change | Best place to edit | Use when |
|---|---|---|
| Most project measurements | Manage > Project Units | You want the project to display mm, m, feet, inches, square meters, or square feet consistently. |
| One dimension style | Dimension Type Properties > Units Format | A dimension should override project units or show alternate units. |
| One tag label | Edit Family > Edit Label > Format | A wall, room, pipe, duct, spot elevation, or custom tag shows the wrong unit. |
| Schedule values | Schedule field formatting | A schedule column needs different rounding, symbols, or units. |
| CAD file scale | Insert/link import units or CAD type properties | A DWG, DXF, or DGN appears too large, too small, or uses the wrong source units. |
The rest of this guide covers each workflow in the order you should usually check them: project units first, then dimension overrides, tag or family label overrides, schedule formatting, and linked/imported file units.
Method 1: Change Project Units in Revit
Project Units is the main Revit unit settings dialog. Use it when you want to change the default display format for the whole project, such as changing length from feet and inches to millimeters, area from square feet to square meters, or slope from rise/run to degrees.
Step 1: Open Project Units
Go to Manage tab > Settings panel > Project Units. The Project Units dialog opens and shows unit types grouped by discipline.
Step 2: Select the Discipline
At the top of the Project Units dialog, choose the discipline you need. Architecture users usually start with Common, but structural and MEP projects may also need structural, HVAC, electrical, piping, or energy units.
Step 3: Click the Format Value
Find the unit type you want to change, such as Length, Area, Volume, Angle, or Slope. Click the value in the Format column. This opens the Format dialog for that unit type.
Step 4: Set Units, Rounding, and Symbol
Choose the unit from the Units menu. Then set Rounding, Unit symbol, and display options such as suppressing trailing zeros, suppressing 0 feet, digit grouping, or suppressing spaces around feet and fractional inches.
Best practice: For architectural metric projects, use millimeters for general length dimensions and square meters for room areas. For imperial projects, use feet and fractional inches for most building dimensions. Use meters only when the project scale or local documentation standard expects it.
Step 5: Click OK
Click OK to close the Format dialog, then click OK again to close Project Units. Check a known dimension, room area, level elevation, and schedule value so you can confirm the project is displaying the units you expected.
Important: Changing Project Units changes the display format. It does not rename loaded families, types, materials, or content. For example, a wall type or door family with “4 inch” or “200 mm” in its name will not automatically be renamed when project units change.
How to Change Units to mm, Meters, or Feet and Inches
Most searches for Revit units are really asking for one of three common changes: millimeters, meters, or feet and inches. The workflow is the same, but the settings should match the way the drawing will be read.
| Goal | Project Units setting | Common rounding |
|---|---|---|
| Change Revit units to mm | Length > Millimeters | 0 or 1 decimal place for building plans |
| Change Revit units to meters | Length > Meters | 2 or 3 decimal places depending on office standard |
| Change Revit units to feet and inches | Length > Feet and Fractional Inches | Nearest 1/8 inch, 1/16 inch, or project standard |
| Show area in square meters | Area > Square Meters | 2 decimal places for rooms, fewer for early studies |
If you are switching an existing template from metric to imperial, or imperial to metric, do more than change Length. Review area, volume, slope, structural units, MEP units, dimension types, labels, schedules, imported CAD files, and loaded content names before using the template on a live project.
Method 2: Change Dimension Units in Revit
Dimension types can follow Project Units, or they can override them. This is useful when the project is metric but one drawing needs imperial dimensions, when a detail needs tighter rounding, or when alternate units should be shown below the main dimension.
For example, you can work in a metric project but create one dimension type that displays Feet and Fractional Inches. You can also keep the primary unit in millimeters and show feet/inches as alternate units for coordination.
Steps
- Select a dimension that uses the style you want to change.
- In the Properties palette, click Edit Type.
- Click Duplicate if you want a new dimension type instead of changing every dimension that uses the current type.
- Give the duplicate a clear name, such as Linear – mm, Linear – meters, or Linear – feet and inches.
- Find Units Format under the Text settings and click the value button.
- Clear Use project settings if this dimension type should override Project Units.
- Choose the unit, rounding, and symbol.
- Click OK to close the Format dialog, then OK again to close Type Properties.
If you changed Project Units and old dimensions still display the previous unit, open that dimension type and check whether Use project settings is turned off. If it is off, the dimension type is using its own custom unit format.
Add Alternate Units to Dimensions
Alternate Units let one dimension show two unit systems at the same time. This is useful for international projects, consultant coordination, or transitional projects where both metric and imperial values must be visible.
- Select the dimension and click Edit Type.
- Duplicate the type if needed.
- Find Alternate Units or Alternate Units Format.
- Choose the secondary unit system, rounding, symbol, and position.
- Click OK and check the dimension in the view.
Tip: Do not edit the default dimension type for a one-off need. Duplicate it first, then use Match Type Properties in Revit to apply the new dimension style to other dimensions.
Method 3: Change Tag Units in Revit
Tags do not always expose their unit settings directly in the project. If a tag label displays a length, area, elevation, slope, diameter, or another measurable value, the unit format is usually controlled inside the tag family label.
This applies to tags such as wall tags, room tags, spot elevation tags, pipe tags, duct tags, structural tags, and custom annotation families that report numeric parameters.
Steps
- Select the tag that shows the wrong unit.
- Go to Modify | Tags > Mode panel > Edit Family.
- In the Family Editor, select the label text.
- Click Edit Label.
- Select the parameter inside the label, such as Length, Area, Elevation, Width, Height, or another measurable parameter.
- Click the Format button on the lower toolbar of the Edit Label dialog.
- Turn on Use project settings if the tag should follow Project Units, or turn it off and choose a custom unit.
- Click OK.
- Load the family back into the project.
- Choose Overwrite the existing version and its parameter values if you are updating the current tag family.
Common mistake: Editing Project Units will not fix a tag family that has a custom label format. Open the tag family, edit the label, and check whether the label parameter is using project settings or a custom unit format.
How to Change Units in Revit Schedules
Schedules can also use project units or custom field formatting. If your room schedule, door schedule, material takeoff, or quantity schedule shows the wrong unit or too many decimals, adjust the field formatting in the schedule.
- Open the schedule view.
- In the Properties palette, click Formatting or Edit next to Formatting, depending on your Revit version and schedule dialog.
- Select the field that needs a unit change, such as Area, Volume, Length, Cost, or Count.
- Click Field Format.
- Use Use project settings when the schedule should match Project Units.
- Clear Use project settings when the schedule needs a custom unit, rounding, or symbol.
- Click OK and review the values in the schedule.
This is helpful when floor plans use millimeters but a room schedule should report areas in square meters, or when a quantity takeoff needs more decimal precision than a drawing tag.
How to Fix CAD Units in Revit
If a CAD file appears huge, tiny, or offset after import, the problem may be the file’s import units rather than Revit Project Units. Revit lets you choose Import Units when importing or linking CAD files, including Auto-Detect, feet, inches, meters, centimeters, millimeters, or a custom factor.
- Go to Insert > Link CAD or Insert > Import CAD.
- Choose the DWG, DXF, or DGN file.
- Set Import Units deliberately instead of leaving Auto-Detect when the source units are known.
- Use millimeters for many metric AutoCAD files, feet or inches for imperial files, or a custom factor for unusual source units.
- Place the file and measure a known distance in Revit to confirm scale.
If the file is already linked, select it and check its type properties for import unit or scale factor settings. When the values are unavailable or unreliable, relink the file with the correct units rather than scaling it by eye.
Do Revit Internal Units Change?
No. Project Units change how values are shown in the user interface. They do not change Revit’s internal database units. For normal modeling, you usually do not need to think about this. It matters more when working with Dynamo, pyRevit, add-ins, the Revit API, imports, exports, or custom automation.
The practical takeaway is simple: use Project Units for drawing display, use unit formatting for dimensions, tags, and schedules, and use proper conversion functions when scripting or importing external data.
Revit Unit Best Practices
Use this checklist before publishing drawings or converting a template:
- Start with the correct Revit template when possible: metric for metric projects, imperial for imperial projects.
- Set Project Units early before many dimensions, tags, schedules, and families are created.
- Review Length, Area, Volume, Slope, Angle, and discipline-specific units instead of changing only Length.
- Duplicate dimension types before changing Units Format.
- Name custom dimension types clearly, such as “Linear – mm” or “Linear – feet and inches”.
- Use alternate units only when the second unit is required; otherwise drawings become harder to read.
- Keep tag labels set to Use project settings unless a tag has a documented reason to override units.
- Check schedule field formatting before assuming the model data is wrong.
- Set CAD Import Units based on the source file, then measure a known distance after linking.
- Rename or reload families when their type names no longer match the project’s display units.
For most projects, consistency is more important than using every available option. Choose one office standard for normal dimensions, one standard for room areas, and a short list of allowed overrides. That keeps plans, schedules, tags, and consultant exports easier to check.
Revit Units Troubleshooting
| Problem | Likely cause | Fix |
|---|---|---|
| Dimensions did not change after Project Units | Dimension type overrides Project Units. | Edit the dimension type, open Units Format, and turn on Use project settings or set the custom unit intentionally. |
| Tags show the wrong unit | The label inside the tag family has a custom format. | Edit Family, select the label, use Edit Label, then Format the parameter. |
| Room areas show too many decimals | Area rounding is too precise in Project Units or schedule formatting. | Change Area rounding in Project Units or in the schedule field format. |
| Family names still say imperial or metric | Project Units do not rename loaded content. | Rename types, load matching content, or rebuild the template with correctly named families. |
| CAD link is too large or too small | Import Units or source DWG units are wrong. | Relink with the correct Import Units and measure a known distance. |
| Feet and inches display as decimal inches | The selected unit is inches instead of feet and fractional inches. | Use Feet and Fractional Inches for normal architectural imperial dimensions. |
Revit Units FAQ
Where are unit settings in Revit?
Go to Manage tab > Settings panel > Project Units. In the Project Units dialog, click the value in the Format column for the unit type you want to change.
How do I change units in Revit to mm?
Open Manage > Project Units, click the Format value for Length, set Units to Millimeters, choose rounding and symbol settings, then click OK.
How do I change Revit from metric to imperial?
Open Project Units and change Length to Feet and Fractional Inches. Then review area, volume, schedules, dimension types, tag families, CAD links, and loaded family names because those may need separate cleanup.
Why did my dimensions not update after changing Project Units?
The dimension type probably has a custom Units Format. Select the dimension, click Edit Type, open Units Format, and check whether Use project settings is turned on.
Can I show metric and imperial units in the same Revit dimension?
Yes. Use Alternate Units in the dimension type settings. This lets the dimension show a primary unit and a secondary unit, such as millimeters with feet and inches.
How do I change units in a Revit family?
For family labels, open the family, select the label, click Edit Label, select the parameter, and click Format. For dimensional family geometry, edit the family parameters and dimensions rather than only changing Project Units.
Does changing Project Units scale the model?
No. Project Units change how values display. They do not resize walls, doors, families, levels, rooms, or the model itself. If something imports at the wrong size, check import units or source file units.
Summary
Use Manage > Project Units when you want to change the default Revit unit display for the project. Use Dimension Type Properties > Units Format when one dimension style needs a different unit or alternate units. Use Edit Family > Edit Label > Format when a tag label is showing the wrong unit.
Before finishing a metric-to-imperial or imperial-to-metric change, check schedules, tags, dimension types, CAD links, and loaded family names. That is the difference between changing a setting and actually cleaning up the project documentation.
Mohamed Fakhry has helped thousands of architects and designers find their next project with step-by-step guidance on his blog, mashyo.com. About Mohamed
His journey began during his university years when he recognized the need for information-rich 3D models to accelerate learning and improve production processes. Now, Mohamed shares his expertise through Revit tutorials that are accessible to all.
