Paint Quantity Calculator: Estimate Litres and Whole Tins for Your Walls

1. Gather these details

• Measure each wall’s width and height in metres. Identify unusually shaped surfaces and sections you will not paint before adding them to the calculation.
• List the areas of doors, windows and other excluded sections. Avoid double counting an opening or subtracting the same doorway twice from one wall.
• Find the selected paint’s coverage in square metres per litre per coat and its tin size in litres. Do not copy coverage from an unrelated product.
• Decide the intended number of coats and a suitable waste allowance with your decorator when needed. The demonstration percentage is not a universal recommendation.
• Calculate ceilings, primer and different colours separately when their assumptions differ. This guide estimates wall paint only, without labour costs or surface preparation charges.

2. Define how the project works

Calculate the surface area first

Add a row for each wall, with width and height in metres. Multiply the two measurements and add the wall areas. Enter excluded opening area separately and subtract it once. If openings exceed total wall area, show a warning because a negative paintable area is not meaningful here. Keep the area breakdown visible so someone can locate a measurement error rather than receiving an unexplained number of tins.

Use the selected product’s coverage

Enter coats, coverage and tin volume. Basic litres equal net area multiplied by coats and divided by coverage per litre. If a label gives a coverage range, choose an appropriate value for the surface with the person doing the work and keep that assumption visible. Do not make the calculator select a paint or diagnose a damp wall. Quantity arithmetic cannot establish the condition of a building or its required preparation.

Allow for waste before rounding tins

Multiply basic litres by one plus the waste percentage divided by 100. Divide the adjusted litres by tin volume and round upward to a whole tin. Show calculated litres separately from purchased litres so remaining paint is understandable. Use one tin size per calculation in the first version. Do not call the result the cheapest purchase combination; optimising a mix of different tin sizes would require additional inputs and separate rules.

Review the assumptions before buying

Copy the inputs and result as readable text and review them with your decorator. If colour, coats or coverage change, recalculate rather than manually overwriting the answer. Include short explanations of coverage and coats beside their fields, plus a reset control. The page should not request addresses or room photographs, and visitors should be able to use it without logging in. Keep all input information local to the calculation without persistent storage.

3. Work through an example

A 4 m by 3 m room with 3 m high walls has the illustrated 42 m² wall area. The ceiling is excluded. Coverage and allowance are example inputs, not universal product advice.

4. Set up your account and start the build

1. Use your account or register.Visit www.gammal.tech/join. New account activation takes 1–10 days. Use a National ID from a country whose citizenship you hold; the official account guide explains the limited exceptions for Egyptian citizens. Submit identity documents only through the official registration process.
2. Activate the WhatsApp subscription.After approval, open my.gammal.tech and add EGP 200 to your wallet, or use sufficient existing funds. Activate the monthly WhatsApp subscription in your account and check that it is active. Funding the wallet alone does not activate it. This subscription covers light personal use; website creation is charged separately.
3. Open the building conversation.Message +201033998844 and send the following command by itself, including the required square brackets. Wait for confirmation of build mode:

   [mode: build]

   [mode: web] is an alternative for the same mode; you only need one command.
4. Send the request in the next section.Replace its placeholders and ask for exactly one page using an available name of at least three characters. Before execution, request an itemised quote separating the one-time build fee, EGP 100 for the first month of standard hosting and any additional usage. Ask how changes beyond the agreed scope are charged.
5. Check the total and approve the build.Once you understand the quote, return to your account and add any missing funds. Return to WhatsApp and confirm the scope and price. Some simple sites take minutes; requirements and revisions affect timing. Open the resulting address and run this guide’s acceptance checks.
6. Record the renewal date.MeNooN hosting renews manually: select the duration and confirm payment before expiry. Leaving funds in your wallet does not renew it automatically. Send [exit], including brackets, when you finish the building conversation.

Budget: quoted build fee + EGP 100 hosting + EGP 200 for one WhatsApp month if it is not already active, plus agreed usage. Twelve months of standard hosting cost EGP 1,200; adding one WhatsApp month makes EGP 1,400 before build and usage fees. Keeping WhatsApp active for further months costs separately.

Service steps and prices reviewed on 18 October 2026. Check the amount shown in your account before paying. WhatsApp steps · Hosting and renewal

5. Adapt and send this request

Replace every bracketed placeholder with your real details. Copy this request after the assistant confirms build mode. Do not publish the illustrative figures as your own.

Build a public ONE PAGE wall-paint calculator on MeNooN called [name], in [language]. No login, storage or address collection. Accept wall rows with width and height in metres, then total excluded opening area. Net area is the sum of each width × height minus openings. Inputs also include positive whole coats, coverage in m² per litre per coat, a nonnegative waste percentage and tin volume in litres. Basic litres equal net area × coats ÷ coverage. Adjust by multiplying by one plus waste ÷ 100. Divide by tin volume and round upward to whole tins. Show units, calculation stages, basic litres, adjusted litres and purchased volume. Reject missing or negative measurements, zero coverage or tin volume, and openings larger than wall area. Do not invent coverage or choose a product. Explain that ceilings, primer and different colours may need separate calculations and surface condition can affect consumption. Use the fictional example of 38 m², two coats, coverage 10, allowance 10% and three-litre tins: 8.36 litres and three tins. Before execution, separately quote the one-time build fee, standard first-month hosting of EGP 100 and any other costs. Wait for my approval.

6. Test the result before relying on it

1. Enter two 4×3 walls and two 3×3 walls, subtract 4 m² and use the example settings.Expected result: Net area is 38 m², adjusted paint is 8.36 L and the result is three three-litre tins.
2. Use 30 m² net area, one coat, coverage 10, zero allowance and a three-litre tin.Expected result: The result is exactly 3 L and one tin; rounding must not add an unnecessary second tin.
3. Enter opening area larger than the walls, then try zero coverage.Expected result: The page requests correction rather than producing negative quantities or dividing by zero.
4. Leave a wall measurement empty, then reset all fields.Expected result: A missing measurement is not silently treated as zero, and reset removes the previous result.

7. Use the project during its first week

Start with one room and ask another person to repeat one wall and opening measurement. Compare the result with handwritten arithmetic before reviewing the inputs with your decorator. During the first week, record questions about units and coats and add concise explanations. If sharing with people preparing their homes, ask them to try the fictional test first. After real work, comparing purchased and used paint may help explain your assumptions, but one room’s outcome should not become a universal allowance for every visitor.

An announcement you can adapt

Preparing to paint a room? Try [website link]. Enter your wall measurements, product coverage and coats to see estimated litres and whole tins. Each step is visible so you can review the assumptions with your decorator before buying.

Questions about this project

Does the calculator include my ceiling?

No, not automatically. Calculate it separately using its actual dimensions and product assumptions. Combining surfaces without checking coverage and coats can create an inaccurate purchase estimate.

Why round upward?

This version assumes whole tins of one chosen size. An 8.36 L requirement needs three 3 L tins. It does not optimise a combination of differently sized containers.

Is a 10% allowance always appropriate?

No. It is an illustrative value. Surface absorption, application and preparation can change consumption, so choose an allowance appropriate to the work with the person carrying it out.