Temperature blanket calculator

A temperature blanket records a year of weather one row at a time, so it can end up far longer than a bed. This calculator works out the rows and finished length before you start, warns you if it will be too long, and builds a colour key in both °F and °C, with equal bands or narrower bands in the middle where most days fall.

How to use the calculator

1. Enter the days and choose one row per day or two days per row.
2. Enter your row gauge and any border.
3. Choose °F or °C, and enter the lowest and highest temperatures you expect. Last year's local records are a good guide.
4. Enter the number of colours, and choose equal bands or narrower-middle bands.

How the calculator works

Rows = days, or days ÷ 2 rounded up for two days per row.

Length = rows ÷ row gauge + 2 × border

Anything over 84 in (213 cm), longer than most beds, gets a warning with options.

• Equal bands split the temperature range evenly: each colour covers (highest − lowest) ÷ colours.
• Narrower-middle bands assume the temperatures follow a bell curve, centred between your lowest and highest values. The mild middle, where most days fall, gets narrower bands and the extremes wider ones, so every colour gets used.

Each band is shown in °F and °C (°C = (°F − 32) × 5 ÷ 9).

Reading your results

• Rows and finished length: in your units, with feet or metres underneath.
• Each colour covers: the width of an equal band.
• Colour key: the range for every colour in both scales.
• Warning: if the blanket will be longer than most beds, with what to change.

Worked example

365 days, one row a day, at 24 rows per 4 in (6 rows per inch), with no border:

• Length: 365 ÷ 6 = 60.8 in, about 5 ft.
• At 12 rows per 4 in it would be 121.7 in, over 10 ft; two days per row brings it to 183 rows and 61 in.
• Ten equal colours across 10 to 100 °F give 9 °F each: colour 1 is 10 to under 19 °F (−12.2 to −7.2 °C).

Accuracy and limits

• The length and bands are exact arithmetic, covered by our automated tests. The real weather will not match your range exactly; days outside it use the first or last colour.
• The narrower-middle option assumes the temperatures follow a bell curve, which suits daily highs in many climates but not all.
• It assumes every row is the same height. A different stitch or a divider row changes the length.

Common mistakes

1. Choosing a tall stitch. Double crochet rows are tall; 365 of them make a very long blanket. Moss or linen stitch keeps it shorter.
2. Guessing the range. Use last year's local highs (or lows) so the extreme colours get used.
3. Too many colours. More colours means narrower bands and more ends to weave in.

Tips for more accurate results

• Measure your row gauge in the stitch you will use, after blocking.
• Missing a day? Repeat the day before, or work a neutral divider row.
• Plan the yarn for each colour from its share of the rows with the stripe calculator.

Frequently asked questions