About the Knitting Increase/Decrease Calculator
This knitting calculator spreads increases or decreases evenly across a row and writes out the instructions for you. Enter the stitches on your needle, how many to increase or decrease, and whether you are knitting flat or in the round. It returns the new stitch count and a line such as “[K13, M1] 4 times, [K12, M1] 4 times” that you can follow directly or copy into your pattern notes.
Patterns often say “increase 8 stitches evenly across the row” without saying how. Dividing the stitch count rarely comes out even, so the calculator splits the remainder into slightly longer and slightly shorter sections so the shaping stays smooth. Use it for hat crowns, yokes, sleeve cuffs, ribbing transitions, blanket borders and resizing patterns.
When knitting flat, increases are kept away from the edges by dividing the row into one more section than the number of increases, and leftover stitches from decreases are split between the two ends. Decreases use k2tog; increases use M1 (make one) or kfb (knit front and back), which works into an existing stitch.
How to use the knitting increase/decrease calculator
- 1Count the stitches currently on your needle.
- 2Enter how many stitches the pattern says to increase or decrease.
- 3Choose increase or decrease, and flat or in the round.
- 4For increases, pick M1 or kfb to match your pattern.
- 5Follow the instruction line, or the section table if you prefer to tick off each repeat.
Formula and method
To spread k shaping stitches over N stitches, divide N into equal sections and work one increase or decrease per section. Because N rarely divides evenly, r = N mod k sections get one extra stitch, so the sections differ by at most one and the shaping looks uniform. In the round the row is a loop, so there are exactly k sections.
Knitting flat, increases go between k + 1 sections so none fall on the edge stitch. For decreases each section ends with k2tog, which uses two stitches; any leftover stitches are split between the beginning and end of the row. With kfb, the increase is worked into the last stitch of a section, so one fewer plain stitch is knitted first.
- N
- Stitches currently on the needle
- k
- Number of increases or decreases
- a
- Base section size (stitches)
- r
- Sections that get one extra stitch
Worked examples
Increase 8 evenly on 100 stitches in the round
100 ÷ 8 = 12 remainder 4, so four sections get 13 stitches and four get 12 (4 × 13 + 4 × 12 = 100). Working M1 after each section adds 8 stitches for a total of 108.
Decrease 9 evenly on 86 stitches, flat
86 ÷ 9 = 9 remainder 5. Each of the nine 9-stitch sections is worked as K7, k2tog, and the 5 leftover stitches are split 3 at the start and 2 at the end, leaving 77 stitches.
Increase 5 on 60 stitches, flat
Knitting flat, the row is split into 5 + 1 = 6 sections of 10 stitches. Increasing between them keeps both edges plain and gives 65 stitches.
Hat crown: decrease 12 on 96 stitches in the round
96 ÷ 12 = 8 exactly, so every 8-stitch section is worked K6, k2tog, removing 12 stitches and leaving 84.
Frequently asked questions
How do I increase evenly across a row?+
Divide your stitch count by the number of increases (or by increases + 1 when knitting flat) to find how many stitches go between each increase. If it does not divide evenly, make some sections one stitch longer — the calculator does this split for you.
How do I decrease evenly in knitting?+
Divide the stitches by the number of decreases to get the section size, then knit each section as “knit to the last 2 stitches, k2tog”. For 96 stitches and 12 decreases that is [K6, k2tog] 12 times.
Should I use M1 or kfb to increase?+
M1 lifts the bar between stitches and is almost invisible, which suits most garments. Kfb is quicker and easier to see but leaves a small purl bump. Use whichever your pattern specifies so the fabric looks consistent.
Why is knitting flat different from knitting in the round?+
In the round the row is a continuous loop, so k increases make k equal sections. On a flat row there are two edges, so increases are spaced between k + 1 sections to keep them off the selvage stitch.
What is the most I can decrease in one row?+
With k2tog each decrease uses two stitches, so you can decrease at most half your stitches in one row (every pair worked together). Bigger reductions need k3tog or two shaping rows.