How much yarn per colour for a temperature blanket?

The short answer

A DK row about 110cm wide takes roughly 10 metres of yarn. A 295m ball of Stylecraft Special DK covers 29 of those rows, so 29 days. Two balls cover 59 days. Three cover 88.

In 2025 the busiest 2 °C band at any of our six places had 53 days. Rounding each band up to whole balls gave 20 to 22 balls in total. The usual ‘2 balls of each colour’ advice would have meant 26 to 32 balls for the same colours, so 6 to 12 balls left over.

For a double-bed blanket about 163cm wide, a row takes nearer 14.4 metres. Then one ball covers only 20 days and two cover 40, and in 2024 between two and six bands per place went over 40 days.

How many days land in each temperature band

The table gives the days in 2025 and then 2024 whose high fell in each 2 °C band. The lower number belongs to the band, so a high of exactly 10 °C counts in ‘10 to 12’. 2024 was a leap year, so its columns add up to 366.

The middle of the range is busier further north and west. In 2025, from 8 to 16 °C, Armagh had 167 days and Leuchars in Fife had 157, against 115 at Heathrow. Heathrow spread its days more widely and had 12 days at 30 °C or above. Armagh had none at 28 °C or above, and Leuchars had one.

Even so, no single band dominates. In 2025 the busiest band ran from 41 days at Waddington to 53 at Armagh. In 2024 it ran from 50 at Waddington to 67 at Cardiff. That is why a heavy pile of balls in one or two colours is rarely needed for a blanket of normal width.

Where the weather numbers come from

We used ERA5-Land, a Copernicus weather reanalysis with a grid of 0.1 degrees, from Open-Meteo’s open data on AWS (licence CC BY 4.0). For each place we took the hourly temperatures for the grid cell over the Met Office station (the nearest land cell at Leuchars, which sits on the coast), then the highest value in each UK calendar day.

At these six stations the grid ran cooler than the Met Office thermometer. In most months it was colder by up to about 3 °C. So we shifted every day in a month by the gap between the grid average and the Met Office’s published mean daily maximum for that station and month. Each month’s average now matches the Met Office figure.

A single day can still be out, and a neighbouring grid cell can move a band by a few days. Treat the counts as a guide to the year, not a day-by-day record. The six stations all have a mean daily maximum for every month of 2024 and 2025 in the Met Office’s historic station data. Cardiff’s July and September 2024 figures are marked as estimated there.

Data credits: Contains modified Copernicus Climate Change Service information 2024–2025 (ERA5-Land, Muñoz Sabater 2019, doi:10.24381/cds.e2161bac). Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains. Weather data by Open-Meteo.com (https://open-meteo.com/), licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/); daily highs derived and bias-adjusted by HazelLoop. Met Office historic station data © Crown copyright. Contains public sector information licensed under the Open Government Licence v3.0 (https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/).

How much yarn one row takes

The crochet version in LoveCrafts’ temperature blanket article starts with 212 stitches in DK on a 4mm hook, works one row of UK double crochet a day and finishes at 111 × 166cm. It doesn’t give yarn quantities, so we worked out metres per row from two published blankets that do.

The Loophole Fox weighed her finished moss stitch blanket, border included, at 4.2lb (about 1,905g), or 5,738 yards of Paintbox Simply DK (302 yards per 100g). It’s 64 inches wide with 365 rows. That works out at 14.4 metres per row, or about 8.9 metres for each metre of width. CrochetKim estimates, for a blanket still in progress, 26 or 27 skeins of Stylecraft Batik DK (151 yards per 50g) for a 45-inch-wide, 365-row afghan. That is 9.8 to 10.2 metres per row, or 8.6 to 8.9 metres per metre of width.

At 8.6 to 8.9 metres per metre of width, a 111cm blanket takes 9.5 to 9.9 metres a row. We rounded up to 10. Both blankets have taller rows than the LoveCrafts one, so 10 metres is likely on the generous side. Your stitch and tension will move this, so crochet one row and weigh it. Ten metres of Special DK weighs about 3.4g, since a 100g ball holds 295m.

Whole balls per colour, place by place

With 10 metres a row, a band of up to 29 days needs one ball, 30 to 59 days need two, and 60 to 88 need three. At 14.4 metres a row, one ball covers up to 20 days, two up to 40 and three up to 61.

At about 110cm wide, one ball was enough for many colours in 2025: 12 of 16 bands at Heathrow, 8 of 15 at Cardiff and 6 of 13 at Armagh. Nothing needed three. In 2024, Cardiff’s 12 to 14 °C band had about 67 days, Bradford’s 10 to 12 °C band about 65 and Armagh’s 12 to 14 °C band about 63. Each of those needed a third ball. Bradford and Armagh were only a few days over the 60-day line, so a slightly different count could tip them back to two.

At about 163cm wide, about the size Leonie Morgan gives for her double-bed temperature blanket pattern in DK (roughly 206 × 164cm), more colours need a third ball. In 2024, Cardiff had six bands over 40 days and Armagh five. Buying 2 of each would have left those colours short.

Next year won’t match last year

The busiest band moves around. Heathrow’s was 16 to 18 °C in 2025, with 48 days, and 12 to 14 °C in 2024, with about 53. Cardiff’s 12 to 14 °C band had about 67 days in 2024 and 38 in 2025. The Met Office’s monthly figures show why: the mean daily maximum at all six stations was 0.7 to 0.9 °C higher over 2025 than over 2024. At Heathrow it averaged 16.3 °C over 2024 and 17.1 °C over 2025.

So plan from more than one year. For each band, take the larger ball count from the two years. At 10 metres a row that gave 22 to 24 balls per place. At 14.4 metres it gave 28 to 31. Allow a ball either way, as the counts depend on the grid cell. NobleKnits suggests starting with one ball of each colour and doubling up on the common temperatures, and the counts here back that up for a normal-width blanket.

Turn the counts into a shopping list

Write down your bands and colours, find your nearest place in the table, and multiply each band’s days by your metres per row. Divide by 295 for Special DK and round each colour up on its own.

The colour explorer shows how rounding each colour separately adds balls compared with one combined total. Our guide to calculating yarn by colour explains why you can’t use spare metres of one shade to cover another. When you have a figure for every colour, put each one into the shopping planner as its own row.

Common questions

Sources and scope

• www.metoffice.gov.uk/research/climate/maps-and-data/historic-station-data
• www.metoffice.gov.uk/pub/data/weather/uk/climate/stationdata/heathrowdata.txt
• www.metoffice.gov.uk/pub/data/weather/uk/climate/stationdata/cardiffdata.txt
• www.metoffice.gov.uk/pub/data/weather/uk/climate/stationdata/waddingtondata.txt
• www.metoffice.gov.uk/pub/data/weather/uk/climate/stationdata/bradforddata.txt
• www.metoffice.gov.uk/pub/data/weather/uk/climate/stationdata/armaghdata.txt
• www.metoffice.gov.uk/pub/data/weather/uk/climate/stationdata/leucharsdata.txt
• registry.opendata.aws/open-meteo/
• open-meteo.com/en/docs/historical-weather-api
• open-meteo.com/en/licence
• www.lovecrafts.com/en-gb/c/article/temperature-blanket-climate-blanket
• theloopholefox.com/crochet-temperature-blanket/
• crochetkim.com/crochetkim-birth-temperature-blanket/
• www.leoniemorgan.com/2020/03/crochet-temperature-blanket.html
• blog.nobleknits.com/blog/how-to-knit-crochet-temperature-blankets
• www.stylecraft-yarns.co.uk/yarns/special-dk
• open-meteo.com/
• creativecommons.org/licenses/by/4.0/
• doi.org/10.24381/cds.e2161bac
• apps.ecmwf.int/datasets/licences/copernicus/
• www.nationalarchives.gov.uk/doc/open-government-licence/version/3/
• www.metoffice.gov.uk/policies/legal

Sources checked 1 October 2026. Label facts come from the linked references; worked purchase examples and arithmetic are our own illustrations.