Home and garden projects

Measure once and let Varlig work out the rest: wall and floor areas, tins of paint, packs of flooring, bags of gravel and what it all costs. Mix metres, centimetres and feet as you like, and change a measurement to see every total update.

Painting a room

Measure the walls, take off the door and window, and turn the area into tins using the coverage printed on the tin.

calc

# Spare bedroom, two coats

long wall = 4 m

short wall = 3.5 m

ceiling height = 2.4 m

walls = 2 * (long wall + short wall) * ceiling height gives 36 m²

door = 0.8 m by 2 m

window = 1.2 m by 1.5 m

paint area = walls - door - window gives 32.6 m²

paint needed = paint area * 2 / 12 sq m/L

paint needed to 1 dp gives 5.4 L

tins = ceil(paint needed / 2.5 L) gives 3

tins at £28 gives £84.00

Lengths multiply into areas, with * or with by the way sizes are written on a plan, and dividing an area by the coverage gives litres. Write the coverage as the tin prints it: 12 sq m/L and 12 m²/L are the same, and an American tin’s 450 sq ft / 400 sq ft/gal works the same way. ceil rounds up, because you can’t buy part of a tin, and tins at £28 prices them. See Arithmetic with units and Function forms.

Flooring an L-shaped room

Split an awkward room into rectangles, add them together, and allow 10% extra for offcuts.

calc

# Living room with a bay

main part = 5.2 m by 3.8 m gives 19.76 m²

bay = 2.4 m by 150 cm gives 3.6 m²

living room = main part + bay gives 23.36 m²

living room in sq ft to 0 dp gives 251 ft²

with waste = living room + 10%

packs = ceil(with waste / 2.2 m²) gives 12

packs at £36 gives £432.00

Metres and centimetres mix freely and the area still comes out in square metres. in sq ft helps when a shop or an old floor plan uses feet. Dividing by the area in one pack gives a plain number of packs. See Squares, cubes and powers.

Gravel and lawn seed

Work out how much gravel a path needs, whether loose bags or a bulk bag is cheaper, and how much seed a new lawn takes.

calc

# Garden path, 5 cm of gravel

path = 6 m * 0.9 m * 5 cm gives 0.27 m³

gravel = path * 1600 kg/m³ gives 432 kg

bags = ceil(gravel / 25 kg) gives 18

small bags = bags at £6.50 gives £117.00

# A bulk bag holds 850 kg for £95

small bags - £95 gives £22.00

# New lawn, seed at 35 g per m²

lawn = 8 m by 5 m gives 40 m²

lawn * 35 g/m² in kg gives 1.4 kg

A depth in centimetres times lengths in metres gives cubic metres, and a density in kg/m³ turns that volume into a weight. Here the bulk bag saves £22 and leaves gravel to spare. See Arithmetic with units.

Timber, sheets and spacings

A build shopping list mixes counts, sheet sizes and inch fittings. Write each line the way the merchant does.

calc

# Loft floor, 3.6 m across, joists at 16 in

3.6 m / 16 in rounded up gives 9

# Six 2.4 m lengths of 4 by 2

6 x 2.4 m gives 14.4 m

# One sheet of 18 mm OSB, and six of them

1200 x 2400 mm gives 2.88 m²

1200 x 2400 mm * 6 gives 17.28 m²

2-1/2" in mm gives 63.5 mm

1 in * 10 in * 8 ft in board feet gives 6.6666666667 bdft

A count in front of a length repeats it, so 6 x 2.4 m is six boards rather than a 6 m by 2.4 m area, while a sheet’s two sides multiply into square metres. A number followed by in before a rounding phrase is inches, which is what makes the joist line work. See Sizes written with by or x.

Insulation and running costs

Insulation is sold by its conductivity and specified by its U-value. Both are written with the kelvin run on to the unit before it, and Varlig reads them that way.

calc

# Loft: 270 mm of mineral wool at 0.04 W/mK

0.27 m / (0.04 W/mK) gives 6.75 m²·K/W

1 / (6.75 m²·K/W) gives 0.1481481481 W/(m²·K)

# Old ceiling was 0.4 W/m2K over 48 m², 15 degrees colder outside

(0.4 W/m2K - 0.1481 W/m2K) * 48 m² * 15 K gives 181.368 W

# An electric heater instead

heater 2kW 5 hours a day for 30 days gives 300 kWh

A thickness over a conductivity gives thermal resistance, and one over that resistance gives the U-value, so the sums from the product sheet come out as they do in the textbook. Writing what a heater draws next to how long it runs gives the energy, and a day for 30 days turns it into a month’s worth. See Units from a textbook or datasheet.

DIY conversions and your own units

Older houses are measured in inches and feet, and DIY shops sell in millimetres. Convert as you go, and define units for the things you’re counting.

calc

# Old house, metric shop

3/4 inch in mm gives 19.05 mm

8 ft in m to 2 dp gives 2.44 m

6'6" in cm gives 198.12 cm

# Fence panels are 1.8 m wide

unit panel = 1.8 m

fence = 14.4 m

fence in panels gives 8 panels

# Splashback in 30 cm tiles

unit tile = 30 cm * 30 cm

splashback = 2.4 m * 0.6 m

splashback in tiles gives 16 tiles

unit panel = 1.8 m defines a unit of your own, and in panels counts how many fit. Feet and inches written with ' and " convert like any other length, and multiply into an area: 12'6" * 10'3" gives 128.125 ft². See Custom units and Heights and weights in feet, stones and pounds.

Make it your own

Measured the room in feet? 14 ft by 12 ft gives 168 ft², and in m² converts it for a metric shop.
Price flooring by the square metre instead of by the pack: living room * £18/m².
Buying carpet cut from a 4 m roll? £22/m² * 4 m gives the price per metre, £88.00/m.
Count wallpaper rolls with unit roll = 5.3 m² and walls in rolls rounded up.
Fill a raised bed: 2.4 m * 1.2 m * 30 cm in L gives the compost you need in litres, and 864 L in bags of 50 L rounded up turns that into 18 bags without declaring a unit first.
Size a water butt: rain 12 mm on 40 m² roof in L gives the 480 litres a downpour puts on the shed roof.
Reframe a print for a metric mount: 11 x 14 in in cm converts each side on its own, 27.94 × 35.56 cm.
Read an American plan: 20 sqm in sq ft gives 215.2782083342 ft², and sq m and m² work the same way.
See what a heater costs to run: 2 kW * 3 hours * 24.5p/kWh gives £1.47, with the tariff written in pence as it is on your bill.
Replace an old radiator rated in BTUs: 5000 BTU/h in W to 0 dp gives 1,465 W.
List a quote the way the merchant writes it: basin + pedestal £145 and taps & waste £62 keep the whole description, and a total line below adds them up. See Words beside an amount.
Set a torque wrench from an American manual: 50 lb-in in N·m gives 5.6492414514 N·m, and 1/4 turn in degrees gives 90° for a fitting tightened by feel.
Spread a cost over the miles: service every 10,000 miles at £180 gives £0.018/mi.