AutoCAD scale calculator

Convert architectural scales and calculate viewport scale factors

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What is the AutoCAD scale calculator?

The AutoCAD Scale Calculator helps drafters and designers convert between architectural scales and calculate the correct scale factors for AutoCAD viewports and annotations.

Working with architectural scales in CAD can be confusing—is 1/4" = 1'-0" the same as 1:48? What DIMSCALE do I need? This calculator clarifies scale relationships and provides the exact values needed for your drawings.

Enter any architectural scale to see equivalent representations, viewport scale factors, and common CAD settings. The calculator handles both imperial and metric scales.

Features

Everything you need

Architectural scale conversions
AutoCAD viewport scale factors
DIMSCALE and LTSCALE values
Plot scale calculations
Imperial and metric support
Common scale reference chart
Bidirectional conversions

How it works

Simple workflow

1
Enter your drawing scale in any format
2
View the scale as ratio, fraction, and factor
3
Get recommended DIMSCALE values
4
Calculate viewport zoom factors
5
Reference the common scales chart

Use cases

Built for real-world scenarios

Viewport setup

Calculate exact zoom XP factors for paper space viewports at standard architectural scales.

Annotation sizing

Determine DIMSCALE settings so text and dimensions plot at correct sizes.

Scale conversions

Convert between architectural notation (1/4"=1'-0") and decimal scale factors.

Print settings

Set up plot scales to print model space drawings at desired scales.

FAQ

Frequently asked questions

1/4" = 1'-0" equals a scale factor of 1:48. In AutoCAD, 1 unit in paper space equals 48 units in model space. For viewports, use ZOOM 1/48XP or 0.020833XP. Set DIMSCALE to 48 for correct dimension sizing.

Convert the scale to a ratio: 1/4" = 1'-0" means 0.25 inches = 12 inches. Scale factor = 12 ÷ 0.25 = 48 (1:48). Use this factor for viewport XP value (1/48) and DIMSCALE. The calculator provides these values for any architectural scale.

DIMSCALE multiplies all dimension sizes in model space. If your viewport is at 1/4" scale (1:48), set DIMSCALE to 48 so dimensions display and plot correctly. Alternatively, use annotative dimensions.

This calculator includes a quick reference for common scales: 1/8"=1'-0" (1:96), 1/4"=1'-0" (1:48), 1/2"=1'-0" (1:24), 3/4"=1'-0" (1:16), 1"=1'-0" (1:12). Each shows scale factor, ratio, and viewport XP value.

Common scales: 1/8"=1'-0" (1:96) for site plans, 1/4"=1'-0" (1:48) for floor plans, 1/2"=1'-0" (1:24) for elevations, 3/4"=1'-0" (1:16), 1"=1'-0" (1:12), 1-1/2"=1'-0" (1:8) for details, 3"=1'-0" (1:4) for large details.

Have a suggestion?

We're always looking to improve our calculators. If you have ideas for new features, improvements, or found something that could work better, we'd love to hear from you.

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