Material calculator
Paint Calculator for Multiple Rooms
Work out the paint for each room, then combine matching products into a purchase.
Your measurements
Changing units changes the display, not the stored measurement.
Results
Example inputs
Your result will appear here
Enter the measurements and product details, then calculate.
These tools estimate material quantities from dimensions you choose. They do not specify structural depth or load capacity.
Select what you will paint
Enter each room’s length, width and height. Select all four walls, the rectangular ceiling or both. Measured door and window openings are deducted from the walls only. The current paint form treats a selected ceiling as a complete rectangle and has no ceiling-opening deduction. Enter each wall opening once.
Wall and ceiling products may differ. Keep them in separate material groups when their product, coverage or purchasing specification differs. A room name helps you recognise a calculation; it does not establish that its paint matches another room.
Enter coats and coverage from your project
Choose the coat count and enter coverage per coat in the stated area-per-volume unit. Coverage is product-specific input, not a universal promise. PackLedge does not decide how many coats a surface needs.
Example: bedroom walls
A room 4 m long, 3 m wide and 2.5 m high has 35 m² of wall area. Deducting 3 m² of measured door and window openings leaves 32 m². With two user-selected coats and an illustrative coverage of 10 m²/L per coat, the paint requirement before allowance is 6.4 L.
A chosen 10% allowance increases the requirement to 7.04 L. If the selected can holds 2.5 L, three cans supply 7.5 L. The 0.46 L difference is purchase surplus beyond the adjusted requirement; the allowance itself was 0.64 L.
Review rooms before combining them
Check each room’s area, coats and coverage. Compatible unrounded paint requirements can be combined before rounding to cans. Different products or can specifications stay separate. Wall openings that exceed the gross wall area need correction; the tool does not silently replace an impossible negative wall area with zero.
What the estimate does not decide
This is a material estimate based on your inputs. It does not assess surface preparation, colour change, application method or the suitability of a coating. Read the selected product’s instructions and replace all example parameters before ordering.
Frequently asked questions
Does ceiling paint use the same calculation?
Its area starts from length × width rather than wall perimeter × height. Keep a different ceiling product or coverage in a separate purchasing group.
Why did the tool reject my opening area?
Wall openings cannot remove more than the gross wall area when walls are selected. Check units, dimensions and whether an opening was entered twice. Openings do not reduce a selected ceiling.
Sources and method
- PackLedge quantity methods
Original derivations using geometry, ratios, sums and whole-package rounding. Each calculator explains its assumptions and worked examples.
- Your selected product label or technical sheet
The source for the coverage, mixed yield, density, package capacity, sheet dimensions or wallpaper repeat that you enter.