Granny Square Calculator
Blanket size to square count, square count to blanket size, and skeins to squares — the three questions every granny square project starts with.
Layout
11 × 13
squares across × down
You need
143
granny squares
Finished size
132×156
cm · 52×61 in
Counts round up so the blanket is never smaller than the target — squares are joined edge to edge, so add a border round per square if you like a looser join.
All math runs in your browser — nothing is uploaded. Estimates assume classic granny squares joined edge to edge; tension and square pattern shift real usage by ±20%. 💕
Keep planning: plan every color arrangement · total yarn for the whole blanket · blanket sizes & starting chains
Granny square blankets are modular, which makes them wonderfully plannable — once you know your square size, everything else is multiplication. This granny square calculator runs the math in both directions: pick a blanket size (baby through king, or your own custom dimensions) and it tells you how many 10, 12, or 15 cm squares you need, with the layout drawn out. Already crocheting? Enter the squares you have and it shows the blanket sizes they can become.
The third tab answers the stash question: how many squares does one skein actually make? A classic 12 cm granny in worsted runs about 25 yards, so a 364-yard skein gives you roughly 14 squares — scaled here for your square size and yarn weight, so you can plan a whole blanket's shopping list from one finished square.
What you get
Blanket → square count
Five standard blanket sizes plus custom dimensions, divided by 10, 12, or 15 cm squares — layout grid and finished size included.
Squares → blanket size
Enter your square count and get the three best layouts, ranked by how close they come to classic throw proportions.
Squares per skein
Yarn weight, square size, and yards per skein → how many squares one skein makes, with multi-color splitting explained.
Visual layout grid
The blanket drawn as the checkerboard of squares it will become — count-checking at a glance.
Counts that round up
The grid always covers the full target size, so the finished blanket is never smaller than the bed it was planned for.
Free, private, no sign-up
Runs entirely in your browser — nothing is uploaded, nothing is tracked.
How to plan a granny square blanket
Make and measure one square
Crochet one square in your chosen yarn and pattern, block it, and measure the edge. Everything on this page keys off that number — the presets cover the common 10, 12, and 15 cm sizes.
Run the count in your direction
Blanket size first? The first tab divides it into a square grid. Squares already made? The second tab shows the blankets they can form.
Plan colors and yarn
Use the skein tab for yarn quantities, then take your square count to the color combinations tool to plan every color arrangement before you join a single seam.
Calculator vs. "make squares until it looks big enough"
| Granny square calculator | Crocheting into the void | |
|---|---|---|
| Knowing when you're done | Exact square count from day one — 96 for a throw in 12 cm squares | You find out at square 70 that you need 30 more |
| Yarn shopping | Squares per skein computed before you buy | Three emergency dye-lot hunts per blanket |
| Using up finished squares | Best layouts for the squares you already have | A bag of 40 squares and no plan |
| Color planning | Count known up front, so color arrangements can be planned too | Running out of the accent color with a row to go |
Frequently asked questions
How many granny squares do I need for a blanket?
Divide the blanket's width and length by your square size and round both up. A 50×60 in throw with 12 cm (4.7 in) squares: 127÷12 rounds to 11 across, 152÷12 rounds to 13 down — 143 squares. In 15 cm squares the same throw takes 9×11 = 99. The calculator above does this for five standard sizes and any custom dimensions.
How many granny squares does one skein of yarn make?
A classic 4-round 12 cm granny square in worsted uses about 25 yards, so a standard 364-yard skein makes roughly 14 squares. DK makes about 12, bulky about 20. Multi-color squares split that across colors — expect about 60% of the yardage in the outer rounds. Weigh one finished square and scale from your yarn's yards-per-gram for the exact figure.
What size is a granny square blanket?
Whatever you make it — that's the joy of modular crochet. Common targets: baby blankets at 30×36 in (about 6×8 in 12 cm squares), throws at 50×60 in (about 11×13), twin bed covers at 66×90 in. The size chart on our blanket calculator page lists all the standards in inches and centimeters.
How do I join granny squares, and does joining change the size?
Whipstitch and mattress stitch add almost nothing; join-as-you-go and crocheted joins can add a round's width per square (1–2 cm). This calculator assumes edge-to-edge joining, so if you plan a chunky join, size your squares slightly smaller or accept the extra drape. A border adds another 2–5 cm per side either way.
How many colors should I use in a granny square blanket?
Three to five is the sweet spot for a cohesive look — one main color, one or two accents, optionally a neutral. Once the calculator gives you a square count, the color combinations tool (linked above) generates every unique arrangement of your palette across the squares, with a checklist so no two are joined alike unless you want them to be.
Is this granny square calculator free?
Yes — free with no sign-up, and it runs entirely in your browser. Your square counts never leave your device.