Realistic total cost including materials, labour, permits, and contingency.

Renovation budgets fail even more predictably than holiday budgets. Industry research on home improvement projects consistently finds actual costs run 20-40% over initial estimates. The reasons are consistent: hidden damage revealed during work, specification upgrades mid-project, longer timelines requiring more labour days, and fixed costs (permits, waste disposal, material delivery) that get forgotten in early estimates.

A proper renovation budget has four layers. Materials — per-square-metre cost varies wildly (50/m² for basic work, 200/m² for premium finishes). Labour — skilled trades cost 200-500/day, which adds up quickly. Fixed costs — permits, skip hire, design fees, delivery fees, building control, protection materials. Contingency — 15-25% depending on project complexity and age of property.

Older properties and structural work carry higher contingency needs because more unknowns are revealed when walls open up. Kitchens and bathrooms typically run at the high end of per-square-metre costs due to multiple trades (plumbing, electrics, tiling, joinery). Simple cosmetic work (paint, flooring) runs at the lower end.

How to use it

Input project area in square metres, material cost per m², labour cost per m², total fixed costs, and a realistic contingency percentage (20% for typical renovation, 25-30% for structural or old property). The tool produces total budget with per-m² breakdown.

What the result means

The total is a realistic all-in budget that accounts for the categories typically missed. If it exceeds available funds, the per-m² breakdown shows which lever has biggest impact — usually material specification (specifying 120/m² instead of 180/m² on a 30m² kitchen saves 1,800 immediately).

Budgeting tool, not a construction quote. Actual project costs vary by region, property type, and specifications.

Run it with sensible defaults

Using project area of 30, material cost per m² of 120, labour cost per m² of 150, fixed costs of 2,500, the calculation works out to 12,720.00. Nudge the inputs toward your own situation and the output recalculates instantly. The defaults are meant as a starting point, not a recommendation.

The levers in this calculation

The inputs — Project Area, Material Cost per m², Labour Cost per m², Fixed Costs, and Contingency % — do not pull with equal force. Not every input has equal weight. Flip one at a time toward extreme values to feel which ones move the needle most for your situation.

How the math works

Sums per-m² costs (materials + labour) multiplied by area, adds fixed costs, then applies contingency multiplier. The working is transparent — you can verify every step yourself in the formula section below. No black box, no opaque "proprietary model".

Revisiting the plan

Budgets are living documents. Re-run this whenever income changes, housing changes, or you notice a recurring overrun in a category. A budget from two years ago is probably already wrong.

What this doesn't capture

Budgets are snapshots of intent. Real spending includes irregular costs: birthdays, one-off repairs, the occasional bad week. Tracking actual spending for a month before fixing any budget usually reveals 10–20% that didn't make the original plan.