FREE PAINT CALCULATOR
Calculate How Much Paint You Need.
Measure walls and ceilings, deduct doors or windows and calculate the paint quantity required for your selected number of coats, coverage and wastage allowance.
You can also switch on an optional Growchance painting and decorating estimate. Results are free and do not require an email address or account.
QUANTITY AND COST PLANNING
Calculate the paint first. Add a project estimate if needed.
The calculator begins with the surfaces being painted and the coverage of the selected product. An optional switch can then add an indicative Growchance painting and decorating range.
MEASURE THE SURFACES
Add each wall or ceiling separately.
Enter the width and height or length of every rectangular surface. Add further areas when rooms contain several walls or ceilings.
- Multiple wall areas
- Multiple ceiling areas
- Optional door and window deductions
- Separate wall and ceiling totals
ENTER THE PAINT DETAILS
Use the coverage stated on the product.
Enter the planned number of coats, product coverage and wastage. Tin information is optional but allows complete tins and material cost to be estimated.
- Number of coats
- Coverage in square metres per litre
- Adjustable wastage allowance
- Optional tin size and price
OPTIONAL PROJECT ESTIMATE
Switch on decorating costs only when required.
Add preparation, skirting, architrave, doors or windows to receive an indicative Growchance range alongside the paint quantity.
- Square toggle controls the estimate
- Ex-VAT and VAT-inclusive ranges
- Standard trade materials included
- Premium products confirmed separately
FREE PAINTING CALCULATOR
Build your initial painting estimate.
Choose a quick project range or enter individual measurements for walls, ceilings, woodwork, windows, preparation and local repairs.
Your result is shown immediately. No email address or account is required, and sending an enquiry remains optional.
Paint quantity and optional painting estimate calculator
OPTIONAL NEXT STEP
Discuss your painting project.
Send the calculation with your project details. This does not create a quotation or contract.
HOW TO USE THE CALCULATOR
From measured surfaces to paint quantity.
Work through the measurements and product information in order. The decorating estimate is optional and can remain switched off when you only need paint quantities.
ADD THE SURFACES
Measure each wall or ceiling.
Select the surface type and enter its width and height or length in metres. Add each rectangular wall or ceiling as a separate area.
SUBTRACT UNPAINTED AREAS
Deduct doors, windows or openings.
Add deductions only for surfaces that will not be painted. Select whether each deduction belongs to the wall or ceiling calculation.
ENTER THE PRODUCT DETAILS
Add coats, coverage and wastage.
Use the coverage stated on the exact paint tin. Add the intended number of coats and wastage. Tin size and price are optional.
CHOOSE WHETHER TO ADD COSTS
Switch on the decorating estimate if required.
Add preparation, skirting, architrave, doors or windows, then review the paint quantity and the separate ex-VAT and VAT-inclusive decorating ranges.
STANDARD CALCULATION BASIS
What the painting estimate normally allows for.
The published Growchance ranges assume a normal residential decorating scope using standard professional trade materials. They are not bare labour-only figures unless specifically stated.
Normal protection
Ordinary masking and protection for floors, fixed items and furniture remaining within the working area.
Minor preparation
Minor filler, light sanding and ordinary caulking associated with surfaces that are generally in reasonable condition.
Paint system
Standard trade paint, normal primer or undercoat where required and two finish coats under ordinary conditions.
Completion
Normal brushes, rollers and consumables, ordinary painting waste, daily tidying and final cleaning of the work area.
Normal sequence included in the guidance.
- Protect the working area
- Prepare the applicable surfaces
- Fill and sand minor local defects
- Apply primer or spot-primer where required
- Apply undercoat where the system requires it
- Apply two standard finish coats
- Complete normal cutting-in and detailing
- Tidy and clean the immediate work area
Product-specific systems can differ. Some specialist, heritage, stain-blocking or anti-mould products require a different manufacturer-specified build-up and must be confirmed separately.
PROJECT-SPECIFIC COST FACTORS
Why the final quotation may differ.
A calculation can organise the known scope, but the condition, specification and working arrangements still determine the final project price.
Surface condition
Cracking, flaking coatings, staining, unstable plaster and damaged surfaces can require substantially more preparation than normal minor filling and sanding.
Paint specification
Premium, designer, heritage, stain-blocking, anti-mould and other specialist products can change both material cost and the required preparation or coating system.
Detailed woodwork
Sash windows, period joinery, balustrades, multiple doors and detailed mouldings require more preparation and cutting-in than simple, modern surfaces.
Access and height
Stairwells, high ceilings, restricted exterior access, scaffolding and specialist equipment can change the labour, sequencing and protection required.
Occupation and furniture
Working around occupants or repeatedly moving substantial furniture can slow protection, preparation, access and drying between stages.
Exterior weather
Exterior work depends on suitable temperature, moisture and drying conditions. The working programme and calendar duration may therefore differ.
UNDERSTANDING YOUR RESULT
Quantities, estimates and VAT are shown separately.
The result panel separates paint-purchasing information from the optional Growchance project estimate so the same material cost is not counted twice.
NET PAINTED AREA
Walls and ceilings after deductions.
The calculator totals the measured rectangles and subtracts the selected door, window or other unpainted areas from the corresponding wall or ceiling result.
PAINT QUANTITY
Litres and optional whole tins.
Litres are calculated from the net area, number of coats, product coverage and selected wastage. Whole tins appear only when a tin size has been supplied.
VISITOR-SUPPLIED MATERIAL COST
The tin price remains a separate result.
If you enter a price per tin, the calculator multiplies it by the required whole tins. Its VAT basis depends on the price supplied by the retailer and is therefore not changed by the calculator.
OPTIONAL PROJECT ESTIMATE
Ex-VAT and VAT-inclusive ranges.
When switched on, the Growchance painting and decorating estimate is shown first excluding VAT and then with VAT added at the configured rate.
The measured wall and ceiling rates include standard trade materials. The visitor-entered tin cost is therefore not added to this range.
CHOOSE THE RIGHT NEXT STEP
Calculator, cost guide or painting service?
Each page answers a different homeowner question. Use the route that matches whether you need quantities, budgeting guidance or help delivering the work.
INTERACTIVE TOOL
Painting Calculator
Measure surfaces, deduct openings and calculate litres, whole tins and an optional painting and decorating estimate.
Best for Paint quantities, tin planning and an initial measured estimate.
Return to the calculatorBUDGETING GUIDE
Painting and Decorating Cost Guide
Review typical London room, property, exterior and preparation ranges, quotation scope and the factors that affect a budget.
Best for Broader price research and understanding complete project costs.
Read the cost guidePROJECT DELIVERY
Painting and Decorating Service
Explore Growchance’s residential interior and exterior painting, preparation, decorating and finishing service in London.
Best for Homeowners looking for a contractor to assess and complete the work.
Explore the painting serviceFREQUENTLY ASKED QUESTIONS
Paint quantities and decorating estimates explained.
These answers explain how to enter measurements, use product coverage and interpret the optional painting and decorating estimate.
01 How does the calculator determine how much paint I need?
It calculates the net wall and ceiling areas, multiplies them by the selected number of coats, adds the chosen wastage allowance and divides the result by the product’s stated coverage per litre.
02 Where can I find the paint coverage figure?
Check the manufacturer’s tin, product data sheet or retailer listing. Coverage is normally stated in square metres per litre. Use the figure for the exact product because coverage varies between primers, emulsions, trim paints and specialist coatings.
03 Should I subtract doors and windows?
Deduct an opening only when that area will not receive the same paint. If a door, frame or window is also being painted with a different product, calculate that finish separately rather than treating it as part of the wall-paint quantity.
04 How many coats should I enter?
The standard Growchance cost guidance normally assumes two finish coats, with primer or undercoat where required. The actual product system depends on the existing surface, colour change and manufacturer instructions.
Calculate primer, undercoat and finish products separately where they have different coverage rates.
05 Why does the calculator include a wastage allowance?
A planning allowance helps account for roller and brush loading, container residue, minor measurement differences and surface absorption. The appropriate allowance depends on the product, substrate and application method.
06 Does the optional estimate show labour only?
No. The approved Growchance measured wall and ceiling rates include standard professional trade paint and ordinary decorating materials. The result is therefore labelled as a painting and decorating estimate, not a labour-only price.
07 Is my entered paint price added to the Growchance estimate?
No. Your tin price is displayed separately as a purchasing estimate. It is not added to the Growchance range because the standard measured rates already include ordinary trade materials. This prevents the material allowance from being counted twice.
08 Is VAT included in the decorating estimate?
The calculator displays the Growchance range both excluding VAT and with VAT added at the configured rate. A retailer’s paint price is left exactly as entered because the calculator cannot determine whether that supplied price already includes VAT.
09 Can I use the calculator for exterior painting?
You may use the quantity calculation when you have the correct exterior-product coverage and coat requirements. However, the optional measured decorating estimate is designed for internal walls, ceilings and the listed internal woodwork.
Exterior access, condition, preparation, weather exposure and scaffolding require a project-specific assessment. See the Painting and Decorating Cost Guide for broader exterior budgeting guidance.
OPTIONAL NEXT STEP
Discuss the property, preparation and finish you need.
Share the available project details and Growchance can review the likely scope, preparation requirements and information needed before providing a project-specific quotation.
London postcode, property type and whether the property will be occupied during the work.
Rooms, ceilings, doors, windows, woodwork or exterior elevations that require preparation and decoration.
Mention cracks, damaged plaster, stains, flaking coatings, access restrictions and whether photographs are available.
Include preferred colours, paint products and whether premium or specialist finishes are being considered.
A calculator result or initial enquiry does not create a quotation, contract or confirmation of availability. Final scope, programme and price are agreed separately.