Crochet blanket calculator, from the bed back to the chain

Because a chain and the fabric worked into it are two different gauges, and almost nobody chains at the same tension they crochet at. A foundation chain is a row of slip-knots pulled through one another with no stitch holding them open, so it draws in — often enough to lose an inch or more across a blanket even when the count is exactly right. There are three standard fixes and all of them work: chain with a hook one or two sizes larger than the body hook and change back for row one, chain loosely on purpose and accept that it looks untidy until the first row opens it up, or skip the chain entirely and use a foundation single or double crochet, which builds the chain and the first row together at one tension.

Three to five rounds of single or half double crochet is the usual range for a blanket, and it matters before you chain rather than after. Each round adds one stitch to each vertical edge and one row to each horizontal edge, so the blanket grows by two stitch-widths across and two row-heights up per round — and because rows are taller than stitches are wide in every crochet stitch above single, a border grows the length faster than the width. This tool takes that off your target before counting the body for exactly that reason. A shell or picot edging is deeper than a plain round, so add its depth to the round count rather than treating it as one.

You are gaining or losing a stitch at the turn, and the usual culprit is the turning chain. Whether it counts as a stitch is the designer's choice, not a rule: if the pattern says the chain-3 counts as a double crochet then you skip the first stitch of the row, and if it does not then you work into it — do one and read the other and you drift by one stitch every row in the same direction. The cure is arithmetic rather than skill. Count the row every tenth row against the number this page gave you, and put a marker in the first and last stitch of a row so you can see the edge you are meant to be working into.

Yes for the stitch count, with two adjustments to make consciously. Add the turning chain for your stitch — one for single crochet, two for half double, three for double — and know whether your pattern counts it as a stitch, because that moves the total by one. Then decide whether you are chaining into the chain or using a foundation stitch, since the second replaces the chain entirely. What you should not do is round the number to something tidier: it has already been moved to the nearest legal multiple of your repeat, and moving it again by hand puts you back where the repeat does not close at the far edge.

Measure the person sitting, and expect something smaller than you think. A lapghan at 36 by 48 inches is the list entry made for this and it works because it stops above the wheels and above the footplate — a blanket long enough to reach the floor catches in a wheel, and one wide enough to hang past the armrests bunches under the elbows. Take the measurement from waist to ankle for the length and across the knees plus a hand's width each side for the width, then treat that as the finished size including the border. This is the case where the named sizes are worth ignoring entirely: the list is trade convention, and a person is not.

Not directly, because a motif blanket is counted in squares rather than in stitches, and the arithmetic moves one layer up. Work out the finished size of one blocked motif including its join, divide your target width by that figure and round to a whole motif, and you have the grid — say a 50 inch throw from 6.5 inch squares is 7 across, giving 45.5 inches plus the border. Then bring one motif's stitch count back here, or to the yardage page, and multiply by the number of motifs. The reason it cannot be automatic is that joining methods consume different amounts: a join-as-you-go adds nothing to the size, while a slip-stitch seam or a joining round adds a measurable strip between every pair of squares.

No, not for a baby under a year old, and the crib row in the size list is there because people ask for the dimensions rather than because the blanket belongs in a crib. American Academy of Pediatrics safe-sleep guidance keeps loose blankets, pillows and soft objects out of the sleep space for the whole first year, and an open crocheted fabric adds a second hazard the guidance does not have to spell out: fingers and toes go through the holes. Made at that size it is a floor mat, a pram cover for a supervised baby, or a keepsake — and a wearable sleep sack is the thing to make if the intention was warmth at night.