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Paint calculator

Paint calculator: litres, US gallons and whole cans of paint and primer for a room, from wall area minus doors and windows, coats and coverage.

آخر تحديث أمثلة تم التحقق منها: 5

m²/L
Printed on the can; wall paints typically cover 10–16 m²/L per coat on a smooth surface.
خيارات إضافية
A standard interior door is about 1.9 m² (20 ft²).
A typical window is about 1.4 m² (15 ft²).
جرّب
Paint cans to buy
cans
Paint cans to buy: 2 cans
عدد صحيح؛ نحو موجب ما لا نهاية
Paint needed
7.38L / 1.95US gal
Area to paint
36.9m² / 397.19ft²
Coverage drops on rough, porous or unpainted surfaces and on strong colour changes; check the can's figure for your surface.

36.9 m² (397 ft²) to paint × 2 coats needs 7.38 L (1.95 US gal), so buy 2 × 5 L cans.

Walls unfolded

Wall 1Wall 2Wall 3Wall 4DoorWindow2.6 m
طريقة الحساب S

  1. Wall area

    2(4.5+3.5)×2.6=41.6 m22(4.5 + 3.5) \times 2.6 = 41.6\ \text{m}^2

  2. Subtract doors and windows

    1×1.9+2×1.4=4.7 m2⇒A=36.9 m21 \times 1.9 + 2 \times 1.4 = 4.7\ \text{m}^2 \Rightarrow A = 36.9\ \text{m}^2

  3. Paint for all coats

    V=36.9×210 m2/L=7.38 LV = \frac{36.9 \times 2}{10\ \text{m}^2/\text{L}} = 7.38\ \text{L}

  4. Whole cans

    ⌈7.38 L5 L⌉=2\left\lceil \frac{7.38\ \text{L}}{5\ \text{L}} \right\rceil = 2

    Rounded up to whole 5 L cans.

حول Paint calculator

Paint needed is the area to cover times the number of coats, divided by the coverage printed on the can. Wall area is the room's perimeter times the wall height, 2(length + width) × height, plus the ceiling if you include it, minus each door and window. The result is rounded up to whole cans of the size you pick.

The default 4.5 × 3.5 m room with 2.6 m walls, one door and two windows leaves 36.9 m² to paint. Two coats at 10 m² per litre need 7.38 L, which is two 5 L cans. For US paint, switch coverage to ft² per gallon; Sherwin-Williams puts a gallon at about 350–400 ft² per coat.

Label coverage assumes a smooth, sealed surface. Bare plaster, rough texture and strong colour changes use more paint, so treat the answer as the minimum to buy.

أمثلة محلولة

4.5 × 3.5 m room, 1 door, 2 windows, 2 coats

Room length
4.5 m
Room width
3.5 m
Wall height
2.6 m
Doors
1
Windows
2
Coats
2
Coverage given as
m² per litre
Coverage per coat
10 m²/L
Can size
5 L
Area to paint
36.9 m²
Paint needed
7.38 L
Paint needed
1.95 US gal
Paint cans to buy
2 cans

مصدر التحقق: ⁨Python decimal: 2(4.5 + 3.5) × 2.6 − 1.9 − 2 × 1.4 = 36.9 m²; × 2 ÷ 10 = 7.38 L; 7.38 ÷ 5 → 2 cans⁩

12 × 12 ft room, 8 ft walls, US gallons

Room length
12 ft
Room width
12 ft
Wall height
8 ft
Doors
1
Area of one door
20 ft²
Windows
2
Area of one window
15 ft²
Coats
2
Coverage given as
ft² per gallon
Coverage per coat
350 ft²/gal
Can size
1 US gallon (3.79 L)
Area to paint
334 ft²
Paint needed
1.91 US gal
Paint cans to buy
2 cans

مصدر التحقق: ⁨Hand calculation: 4 × 12 × 8 = 384 ft² − 20 − 30 = 334 ft²; 668 ÷ 350 = 1.9086 gal → 2 one-gallon cans⁩

Walls and ceiling with primer, 2.5 L cans

Room length
5 m
Room width
4 m
Wall height
2.5 m
Doors
0
Windows
0
Paint the ceiling too
نعم
Coats
2
Coverage given as
m² per litre
Coverage per coat
10 m²/L
Add one coat of primer
نعم
Can size
2.5 L
Area to paint
65 m²
Paint needed
13 L
Paint cans to buy
6 cans
Primer needed
6.5 L
Primer cans to buy
3 cans

مصدر التحقق: ⁨Python decimal: 45 m² walls + 20 m² ceiling; 130 ÷ 10 = 13 L → 5.2 → 6 cans; primer 6.5 L → 2.6 → 3 cans⁩

US room with primer at its own 250 ft²/gal coverage

Room length
12 ft
Room width
12 ft
Wall height
8 ft
Doors
1
Area of one door
20 ft²
Windows
2
Area of one window
15 ft²
Coats
2
Coverage given as
ft² per gallon
Coverage per coat
350 ft²/gal
Add one coat of primer
نعم
Primer coverage
250 ft²/gal
Can size
1 US gallon (3.79 L)
Area to paint
334 ft²
Primer needed
5.06 L
Primer cans to buy
2 cans

مصدر التحقق: ⁨Python decimal: 334 ft² ÷ 250 ft²/gal = 1.336 gal × 3.785411784 L = 5.0573 L → 2 one-gallon cans⁩

الأسئلة

How much paint do I need for a 12 × 12 room?

About 2 US gallons for two coats on the walls. A 12 × 12 ft room with 8 ft walls has 384 ft² of wall; less one 20 ft² door and two 15 ft² windows, 334 ft² remains. Two coats is 668 ft², which at 350 ft² per gallon is 1.91 gallons. Painting the 144 ft² ceiling as well raises the total to 2.73 gallons.

How many square feet does a gallon of paint cover?

About 350–400 ft² per coat, according to Sherwin-Williams, and a quart covers about 100 ft². In metric, 350–400 ft² per US gallon is 8.6–9.8 m² per litre. Use the figure printed on your own can, because coverage changes with the product, the colour and the surface.

How many coats of paint do I need?

Two for most walls. Dulux's guide gives one coat for its Simply Refresh one-coat range and two for EasyCare Washable & Tough. Every coat adds the full area again: the default 36.9 m² room needs 3.69 L per coat at 10 m² per litre, so a third coat adds another 3.69 L.

Should I subtract doors and windows when calculating paint?

Yes. Dulux's method measures each wall as height × width and deducts doors and windows measured the same way. This calculator uses 1.9 m² (20 ft²) per door and 1.4 m² (15 ft²) per window unless you enter your own sizes under More options. In the default room the three openings remove 4.7 m², 11% of the 41.6 m² of wall.

How much primer do I need?

One coat over the whole area, at the primer's own coverage rate. Sherwin-Williams gives about 200–300 ft² per gallon for primer against 350–400 ft² for paint, so 334 ft² of wall takes 1.1–1.7 gallons of primer. Enter the primer label's figure as Primer coverage under More options; left blank, the paint's coverage is used.

ما مدى دقة «⁨Paint calculator⁩»؟

تعتمد الدقة على مدخلاتك وافتراضات الطريقة. يستخدم الحساب العشري 50 رقمًا معنويًا، لكن التقديرات والأساليب العددية وبيانات المصدر قد تكون أقل دقة؛ تقريب القيم المعروضة لا يزيل هذه الحدود. أمثلة محلولة جرى التحقق منها بمصادر مستقلة: 5. مثلًا، يجري التحقق من «⁨4.5 × 3.5 m room, 1 door, 2 windows, 2 coats⁩» بالرجوع إلى ⁨Python decimal: 2(4.5 + 3.5) × 2.6 − 1.9 − 2 × 1.4 = 36.9 m²; × 2 ÷ 10 = 7.38 L; 7.38 ÷ 5 → 2 cans⁩.

ما مصدر هذه الطريقة؟

Dulux UK — how much paint do I need (area ÷ coverage × coats); Sherwin-Williams — paint calculator (paint 350–400 ft² per gallon per coat, primer 200–300 ft²).

حول هذه الحاسبة

V=(2(ℓ+w)h+Aceiling−Adoors−Awindows)×coatscoverageV = \frac{\big(2(\ell + w)h + A_{\text{ceiling}} - A_{\text{doors}} - A_{\text{windows}}\big) \times \text{coats}}{\text{coverage}}

المصادر

  1. Dulux UK — how much paint do I need (area ÷ coverage × coats)
  2. Sherwin-Williams — paint calculator (paint 350–400 ft² per gallon per coat, primer 200–300 ft²)

تم التحقق بالرجوع إلى المصادر

تتضمن هذه الحاسبة أمثلة محلولة بإجابات من مصادر مستقلة، وعددها 5. تُشغّل ضمن مجموعة الاختبارات، ويمكنك تشغيلها هنا أيضًا.

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