Don't run out of thread halfway through a stitch. Plan your project with our accurate estimator for saddle stitching and sewing machines.

Total Thread Required
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Per Seam: --
Safe Estimate (Range): --
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How is this calculated?

Saddle Stitch (Advanced): We calculate the number of stitches based on your spacing. Per stitch, we account for the thread traveling through the thickness of the leather (twice) plus the travel between holes, multiplied by a path factor loop. We then add your tail allowance and safety margins.

Formula: (Stitches × Per_Stitch_Usage) + Tails + Waste%

Simple Mode: Uses a standard 4x multiplier of the seam length.

Machine Stitch: Estimates based on a consumption factor (approx 3x length) covering both top and bobbin thread.

Frequently Asked Questions

What multiplier should I use for saddle stitch?
A common rule of thumb is 3.5x to 4x the length of your seam. However, thicker leather needs more thread (up to 5x), while thinner leather needs less. Our calculator adjusts this for you in 'Advanced' mode.
What is SPI and how do I convert it?
SPI stands for "Stitches Per Inch". To convert to mm: 25.4 divided by SPI equals the spacing in mm. For example, 7 SPI is roughly 3.6mm spacing.
Why does thickness affect thread usage?
In a saddle stitch, the thread passes all the way through the leather and back for every single stitch. The thicker the leather, the more "vertical" distance the thread travels, adding up significantly over a long seam.
Should I wax thread / does it change length needed?
Waxing protects the thread and makes stitching easier/smoother. It doesn't significantly change the length required, but it does secure the knots better. Always use waxed thread for saddle stitching!
What margin should I add for beginners?
It's always better to have too much than too little. We recommend adding at least 15-20% for waste, plus reasonable tails (10-15cm total) so you can comfortably finish your backstitch and trim.

Stock Up for Your Project

Ritza Tiger Thread
Ritza Tiger Thread
The world's favorite braided polyester for hand stitching.
John James Needles
Saddle Stitch Needles
John James harness needles for smooth piercing.
Tokonole Burnishing Gum
Tokonole Burnishing Gum
Glass-smooth edges in seconds.
Thread Zap
Thread Zap
Seal your thread ends instantly.
Leather Adhesives
Leather Adhesives
High-strength bonds for every project.