Construction & Home Improvement Calculators
Free, private, browser-based tools for painting, tiling, concrete, renovation budgets and more. No sign-up, no tracking, instant results.
All calculators
Click any tool to open its calculator, formula explanation, use cases and FAQ.
Paint Calculator
Gallons of paint for walls and ceiling, doors and windows subtracted.
Open tool →Tile & Floor Calculator
Estimate tiles, boxes and cost for any floor layout.
Open tool →Concrete Calculator
Cubic yards, 80 lb bags and delivery cost for slabs.
Open tool →Wallpaper Calculator
Rolls and cost with doors, windows and pattern waste.
Open tool →Renovation Budget
Full reno cost with US/UK/CA/AU regional indexes.
Open tool →Room Area
Square feet, square meters and perimeter from any rectangle.
Open tool →Framing Lumber
2x4 studs, plates and board feet for any wall.
Open tool →AC / BTU Size
Size a room air conditioner in BTU and tons.
Open tool →Gravel & Landscape
Cubic yards, tons and bags of gravel or mulch.
Open tool →No tool matches your search.
Why LeeChuanjing exists
Most homeowners and small contractors do the same five math problems on every job: how much paint, how many tiles, how many yards of concrete, what the reno will cost, and what size air conditioner to buy. Spreadsheets and phone calculators work, but they are easy to fat-finger. LeeChuanjing puts each calculation behind a clean form with the formula, real-world use cases and a FAQ - so you can check your number and understand why it is what it is.
Private by design
Every calculation runs entirely in your browser (JavaScript). Nothing is uploaded, and the site does not set advertising or analytics cookies by default. When we later add optional ad support, it will be clearly separated from the tools and you can still use everything for free.
Estimates, not engineering
These tools are for planning and sanity-checking quotes. Structural, electrical and HVAC work should always be confirmed by a licensed professional and local code. See the disclaimer for details.