Sewing calculators that do the math for you
From your first seam allowance to your tenth quilt binding — thirty-six free tools for measurements, fit, fabric, construction, quilting, home decor, and machine troubleshooting.
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Measurements & Conversions
Seam Allowance Calculator
Find the cut size you need from a finished measurement, at any seam allowance width.
Fabric Yardage Calculator
Convert a pattern's yardage requirement between different fabric widths.
Bias Tape Length Calculator
Estimate how much continuous bias tape a square of fabric will yield.
Metric ↔ Imperial Conversions
Convert inches, centimeters, yards, and meters, plus a fractional-inch chart.
Thread Weight Conversion Chart
What 12wt through 100wt actually mean, and when to use each.
Pattern & Fit
Pattern Grading Calculator
Resize a pattern measurement up or down using a grade rule increment.
Ease Allowance Guide
Typical wearing ease by fit category, from fitted to oversized.
Hem Allowance Calculator
How much extra length to cut below the finished hemline, by hem style.
Dart Manipulation Guide
Estimate total dart intake from the bust/waist difference on a basic bodice.
Button & Buttonhole Spacing
Evenly space any number of buttons along a placket.
Sleeve Length Calculator
Pattern length to cut from a shoulder-to-wrist measurement, ease, and hem.
Fabric & Materials
Fabric Shrinkage Calculator
Test a swatch, then find the cut size that shrinks down to your target.
Interfacing Weight Guide
Match interfacing weight and type to your fabric and garment area.
Fabric Weight Conversion
Convert fabric weight between GSM and oz/yd².
Directional/Nap Yardage Calculator
Estimate the extra yardage napped or one-way print fabric needs.
Needle Size Chart
The right needle size and point type for your fabric.
Sewing Setup Generator
Needle, thread, and stitch length together, for any fabric.
Garment Construction
Zipper Length Guide
Typical zipper lengths by garment or project type.
Elastic Length Calculator
Cut length for a relaxed, fitted, or snug waistband.
Bias Binding & Piping Length
How much binding or piping to cut for an edge, based on its shape.
Gathering Ratio Calculator
Strip length to cut for a ruffle at any fullness ratio.
French Seam Allowance Guide
Split a total seam allowance into the two French seam passes.
Waistband Calculator
Cut length and width for a fitted waistband with closure overlap.
Pleat Calculator
Fabric width to cut for knife or box pleats at any depth.
Quilting
Quilt Backing Calculator
Backing yardage with overhang, piecing panels if your top is wide.
Quilt Binding Calculator
Strips and yardage needed to bind a quilt of any size.
Quilt Block Size Calculator
Work backward from a finished quilt size to the block size you need.
Bobbin Thread Estimator
How many bobbins to wind before starting a long quilting project.
Quilt Batting Calculator
Batting size and yardage needed, with overhang for the frame.
Machine & Troubleshooting
Stitch Length Guide
Recommended stitch length in mm, by fabric weight and purpose.
Thread, Needle & Fabric Chart
Fabric, needle, and thread weight, matched all together.
Common Machine Problems Guide
Skipped stitches, bunching thread, and other usual suspects.
Tension Troubleshooting Guide
Diagnose tension issues by where the loops show up.
Machine Maintenance Guide
A routine upkeep schedule that prevents most common problems.
Home Decor
Pillow Insert Size Guide
Standard insert sizes, and how much bigger than your cover to size up.
Curtain Panel Calculator
Fabric width and length per panel, based on rod width and fullness.
From Our Sewing Room
A write-in planner with room for every project — plus the reference charts from this site built right in.
Sewing Project Planner
120 pages — 50 project spreads, a construction checklist, a fabric stash log, and a finished projects index.
Why these numbers matter
Every one of these tools solves the same basic problem: sewing runs on measurements, and most of those measurements aren't the ones a pattern hands you directly. A seam allowance has to be added on top of a finished size, a ruffle strip has to be cut longer than what it gathers into, a quilt backing has to be bigger than the top — none of it is guesswork once you know the relationship, it's just math that's easy to get wrong under a deadline.
Built for beginners and advanced makers alike
A first-time sewist reaching for a needle size chart and a quilter calculating backing yardage for a queen-size quilt are solving the same kind of problem at different points in their skill level. These tools stay useful the whole way through — the math doesn't change, only what you're applying it to.