About Bobbin & Form
Where thread takes shape — and the story behind the name.
The bobbin
A bobbin is the small spool that carries thread beneath the needle. Nobody photographs it, but every lockstitch depends on it: the quiet, precisely wound supply of thread that makes the visible part of the seam possible. It stands for the part of the craft we do best — the measured, unglamorous preparation: yardage math, thread consumption, grain lines, hoop tensions.
The form
Form is what the thread becomes — the drape of a bias skirt, the crisp corner of a quilt block, a garment that actually fits. It is the reason the preparation matters. We name ourselves after both halves of the craft, because a beautiful form that starts from a wrong number usually ends up unpicked.
Why this site exists
It started with a ruined piece of linen. A first circle skirt was cut from a yardage guess lifted off an inconsistent blog, the fabric came up short, and the “project” became a learning experience about seam allowances and humility. The fix was embarrassingly simple: a real formula, the bolt width, and a calculator.
Sewing is full of that gap. Patterns assume knowledge, blogs round numbers carelessly, and forums argue from memory — while the actual math of a quilt, a hem or a hoop is completely knowable. Bobbin & Form was built to close that gap: free calculators with visible formulas, guides tested at the machine, and a glossary of the words nobody defines properly. No signup, no paywall, no tool you have to trust on vibes.
Today the library serves sewists, quilters and embroidery practitioners around the world — people cutting fabric in Nairobi, hooping designs in Ohio and drafting blocks in Osaka. The thread and the shape are the same everywhere.
- free calculators
- 63
- published guides
- 38
- technique walkthroughs
- 17
- glossary terms
- 1
What we publish
Every number derived from a stated formula you can check — never a vibes-based estimate.
GuidesProblem-first walkthroughs, written the way you would actually want to read them at the machine.
TechniquesStep-by-step craft methods, from seam finishes to hoop management, with the why in every step.
GlossaryPrecise definitions of the words the pattern industry never quite explains — like bias, ease and WPI.
How we work
- Every formula is stated on the page so you can check it — and results are sanity-tested against standard references like Threads Magazine — fabric cutting & yardage guides.
- Content is written by practicing sewists (Bobbin & Form Editorial Team) and reviewed by Marie Delacroix, Custom sewist & machine-embroidery technician, 15 years at the machine.
- Estimates are labelled as estimates. Where craft variability dominates, we tell you to swatch first — see our disclaimer.
- We earn occasionally through affiliate links — never through placement. Corrections and partnership questions go to hello@bobbinform.com.
Start with a number you can trust
Pick a calculator, type your measurements, and cut with confidence.
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