iPhone & iPad · Inches & centimeters · No subscription

The sewing math your phone should have done years ago.

Found the perfect fabric, but it's 60″ wide and your pattern says 45″? SewCalc converts the yardage, sizes the quilt, adds the seam allowance and cuts the elastic — and answers in the fractions on your tape measure. No account, no ads, and it works in a craft room with no signal.

$2.99 once. Less than a fat quarter.

Buy: 2⅛ yd

Data Not Collected

15-second tour

Meet Bobbin. It explains SewCalc faster than we can.

Yardage, patterns, seams, quilts, elastic and bias tape, in one breath. Turn your sound on.

Calculators for the math you do every project

⅛ yd

Always rounded up, so you never run short

in ⇄ cm

Imperial or metric, fractions or decimals

0 bytes

Collected. Everything stays on your device

Built for the cutting table

Stop Googling formulas mid-project.

General unit converters don't know what a bolt width is. SewCalc speaks sewing: yards in eighths, seams in fractions of an inch, quilts in blocks and borders.

Yardage converter with common bolt widths reference

Fabric yardage

Different bolt width? Know exactly how much to buy.

The pattern asks for yardage at one width, but the fabric you love comes in another. Enter both and SewCalc converts it, then rounds up to the nearest ⅛ yard — the way the cutting counter sells it. Rounding down is how you end up a sleeve short.

2¾ yd @ 44/45″→2.074 yd @ 58/60″→Buy 2⅛ yd

A bolt-width reference is built in: 36″ silks, 44/45″ quilting cotton, 54″ home décor, 58/60″ apparel, 72″ felt and fleece.

Quilt planner

A whole quilt, measured before you cut a single square.

Enter the block size, blocks across and down, sashing, borders and seam allowance. SewCalc gives you the finished quilt top, then the fabric for blocks, sashing, each border, pieced backing and binding strips — a shopping list for the quilt shop.

Quilt top 66 × 78 in→Backing 4⅞ yd · Binding ½ yd

Quilt tab showing a 66 by 78 inch quilt top and fabric needed for blocks, sashing, border, backing and binding

Seam tab adding a 5/8 inch allowance to a 6.5 inch square for a 7¾ inch cut size

Seam allowance

Finished size in. Cut size out. Or the other way round.

Add ¼″ for piecing, ⅝″ for garments, 1″ for fitting room — on all sides, top and bottom, or left and right. Switch to Find Finished Size to work backwards from a piece you've already cut.

6½ × 6½ finished + ⅝″→Cut 7¾ × 7¾

Elastic & bias tape

Elastic that fits. Bias tape that reaches.

Pick woven, knit or braided elastic and SewCalc applies the right stretch ratio plus your joining overlap. For bias tape, enter the total length you need and it tells you the fabric square and yardage to cut it from — before you start cutting strips.

32″ waist · knit at 80% + 1″→Cut 26⅝″ · buy 27″

Notions tab with an elastic calculation: 32 inch body measurement, knit elastic, 26.6 inch cut length

2⅛

Real fractions

Every answer in eighths and sixteenths — the marks on your ruler — next to the decimal. Nobody cuts 2.074 yards.

125%

Pattern resize

Scale a piece by percentage, or between sizes: tell it the original and new waist, and it gives you the factor and the new measurement.

in ⇄ cm

Your units

Inches and yards or centimeters and meters, with decimal commas where your region uses them. Switch in Settings any time.

SewCalc privacy screen: Data collected none, network calls zero, analytics none

Yours, privately

No account. No ads. No signal needed.

Sewing rooms are in basements and spare bedrooms, not next to the router. SewCalc makes zero network calls — every calculation happens on your device, and the App Store privacy label reads "Data Not Collected."

Works fully offline

Zero data collected

No analytics, no ads

iPhone and iPad

Pay once. Sew forever.

You just spent more than this on a spool of thread and a seam ripper. SewCalc costs the same, forever.

SewCalc: Sewing Calculator

$2.99

once.

All six calculators. Every future update. No in-app purchases, no upsells, no subscription.

What getting the math wrong usually costs

An extra half yard "just in case"

On every project, because the width conversion felt shaky

$5–$15

Running short at the cutting table

A second trip to the shop, and the dye lot is gone

a project

A general unit converter

Knows inches. Doesn't know bolt widths, seams, or quilts

"free"

SewCalc

Six sewing calculators that answer in fractions

$2.99 once

Questions from the sewing room

Why does it round up instead of to the nearest?

Because fabric is sold in ⅛ yard increments, and rounding down means not enough fabric. SewCalc shows the exact figure and a "Buy" amount rounded up to the next eighth.

Does it work in metric?

Yes. Switch between inches/yards and centimeters/meters in Settings, and choose whether answers show fractions alongside decimals.

Does it need an internet connection?

Never. SewCalc makes zero network calls. Every calculation runs on your device, so it works anywhere you sew.

Where is my data stored?

Nowhere but your device. There's no account, no cloud and no analytics. The App Store privacy label reads "Data Not Collected."

Is $2.99 really the whole price?

Yes. One purchase, every calculator, every future update. No subscription, no in-app purchases, no ads.