Free drawing scale calculator
Work out a scale multiplier, percentage and proportional height in inches or millimeters. Then carry your target width into the vector PDF preview, or use the result in your own design software.
Free · No file or signup needed
Drawing scale calculator
Enter the width you measured and the width you want. Use drawing dimensions, not the paper margins.
Preview a vector PDF at 100 mm wide →Your target width carries over. Choose a compatible PDF next; height will follow its actual outlines.
Preview free. Both SVG + DXF exports cost $5 per selected page. Always verify a known measurement after importing.
Before & after width
Current 50 mm
Target 100 mm
The bars compare physical widths after converting units. They are a screen illustration, not a ruler or print-size preview.
How this result is calculated
100 mm ÷ 50 mm = 2×
2 × 100 = 200%
Height uses the same multiplier: 30 mm × 2 = 60 mm.
This calculates dimensions only; it does not check PDF compatibility or resize a file. A percentage is the final scale, not the percentage increase. For example, 200% doubles the size. The converter also checks page-size and complexity limits.
Make the numbers work for your drawing
The scale multiplier is the target length divided by the current length, using the same units. Apply that multiplier to every dimension to keep the shape in proportion. For example, an 80 × 40 mm drawing resized to 60 mm wide becomes 60 × 30 mm: 60 ÷ 80 = 0.75, or 75% of the original size.
Does 200% mean double the size?
Yes. Entering 200% as the final scale doubles each length. A 50 × 30 mm drawing becomes 100 × 60 mm. It is a 100% increase in width, not a 200% increase. Area becomes four times larger because both width and height double.
How do I change a 1:100 drawing to 1:50?
For scale labels written as 1:n, divide the current denominator by the target denominator: 100 ÷ 50 = 2. Enlarge each length to 200%. Going the other way, from 1:50 to 1:100, uses 50 ÷ 100 = 0.5, or 50%. This assumes the source drawing really matches its scale label; a fit-to-page export or print can change it. Verify a known length.
Why are 25.4 mm and 1 inch shown as the same size?
They are the same physical length. Converting units alone does not enlarge or shrink a drawing. The calculator converts both widths to millimeters before dividing, so 25.4 mm to 1 inch gives a multiplier of 1 and a final scale of 100%.
Can I use the result for a printer or another editor?
You can use the multiplier or final percentage in software that supports proportional scaling. Set it deliberately and check a known dimension on the result. Printer fit-to-page options, margins and application import settings can change the final size. The calculator itself does not edit a file or control a printer.
Follow a real two-page PDF example, with free practice files →
1. Start with outlines, not a scan
This tool extracts existing paths. It does not trace photographs or scanned pages. Use a PDF under 5 MB and choose a page containing plain vector outlines. Other pages can contain instructions; only the selected page is converted. Text, clipping and effects are rejected. If a design contains lettering, convert it to paths in your design software first, then check the resulting file here.
2. Set the width you need
Choose Set drawing width, enter a width, and select inches or millimeters. For example, enter 6 inches for a drawing 152.4 mm wide. Height changes in proportion. This sets the combined width of all outlines on your selected page, not the width of each separate piece. Check a known measurement in your destination software.
Or use a scale multiplier
At a multiplier of 1, the export uses the dimensions represented by the PDF page. If a 100 mm part is drawn 10 mm wide in a 1:10 drawing, a multiplier of 10 makes the outline 100 mm wide. A scale label does not prove the PDF was saved at that scale: verify a known length.
3. Compare the drawing size, not only the page size
Page size includes blank margins. The preview also reports the bounding width and height of the extracted outlines. Neither automatically identifies the size of an individual part when a page contains several shapes.
4. Choose your output and verify it
Both formats are included for $5. SVG retains cubic curves. DXF approximates curves with line segments within a 0.02 mm tolerance and declares millimetres. Import behavior varies by software, so measure a known feature after import. Colors, fills, stroke thickness and dash patterns are discarded.
Try a known-size example first
The converter’s free practice PDF has instructions on page 1 and a 100 × 50 mm tag outline on page 2. Open it with a 4-inch target: the drawing becomes 101.60 × 50.80 mm, or 4 × 2 inches. Its SVG and DXF downloads are free. This demonstrates file sizing; it is not a tested cutting plan.
Try the free practice PDF · Open the converter
Previewing is free. Only continue to the $5 checkout if the extracted outlines and dimensions meet your needs. No subscription.