Painting Quote Calculator
Enter rooms in square metres, coats and your labour rate. The calculator prices the job with GST, the same engine the Kastrion app runs.
A painting quote calculator turns room measurements into a price. Enter your wall and ceiling area in square metres, the number of coats, and your hourly labour rate; it works out the labour hours, the paint and materials, and the total with GST. This one runs the real Kastrion estimating engine, so the maths matches the app.
How it calculates
Area drives everything. Your square metres set the paint volume through the spread rate, and the labour hours through the production rate for that surface. Labour hours times your rate is the labour cost; paint, primer and sundries are the materials. The two add to the ex-GST subtotal, and GST is added on top if you are registered. That is the same sequence the Kastrion app runs, on the same engine.
What the inputs mean
Walls and ceilings are entered as finished square metres. Coats are your top coats; tick the primer box to add an undercoat. Your labour rate is your charge-out rate per hour, so the labour figure reflects what you actually charge. Paint coverage per litre comes from the engine’s spread rates as a starting point and should be checked against your product’s data sheet.
Save it as a real quote
The calculator prices one job in the browser. To keep it, add every room, attach photos and send it, carry the numbers into the app: your figures become your first real quote, no re-keying.
For homeowners
If you are a homeowner pricing a repaint, this tool estimates what the work involves, but it is built for painters setting their own rates. Treat the total as a guide to the size of the job, not a fixed price, and get a written quote from a painter for the real figure.
Frequently asked questions
How is a painting quote calculated?
From area and coats. Wall and ceiling square metres set how much paint the job needs and how many labour hours it takes at your production rate. Labour hours times your hourly rate is the labour cost; paint and sundries are the materials; add them, then add GST if you are registered. This calculator runs that on the same engine the Kastrion app uses.
What coverage does one litre of paint give?
It depends on the paint and the surface. Dulux’s Wash&Wear Low Sheen data sheet lists a theoretical spread rate of 16 m² per litre per coat under recommended film builds; primer, unsealed or textured surfaces draw more, and practical coverage is lower. Check the data sheet for the product you are using. The calculator uses the engine’s built-in spread rates as a starting point.
Does the quote include GST?
Only if you tell it to. Tick "I am registered for GST" and it adds 10% and shows the GST line and the GST-inclusive total. Leave it off and the total is the ex-GST figure. Whether you must charge GST depends on your registration, not on this tool.
Can I save the quote?
Yes. "Save this as a real quote" carries your numbers into the Kastrion app, where you can add every room and line item, attach photos, and send it. The free calculator here prices the job; the app keeps it.