Renovation Budget Calculator

Introduction

A single lump sum on a quotation is hard to audit: materials, labour and sundries are mixed together, and variations later push the spend over the plan. This page treats floor area and the unit price as the base, splits that base into materials, labour and other costs using the shares you enter, then adds a separate contingency line.

The example uses 100 m² at CNY 1200 per m², with materials at 38, labour at 26 and contingency at 8. Base cost is 120000, materials 45600, labour 31200, other costs 43200, contingency 9600, and the total 129600, which works out to 1296 per m².

Every share is applied to the base cost, not to the final total. Changing the area or the unit price moves all six figures together, and the breakdown keeps each intermediate step so a mismatch can be traced back.

Key features

• Base cost: Built-up area times the per-square-metre rate gives the base construction cost.
• Three shares: Material, labour and other costs are split by percentage. A sum above 100 is rejected.
• Contingency: A contingency share is computed on the total and is not folded into materials.
• One total: All lines sum to a single budget. Changing the rate or a share updates it immediately.
• Back per m²: Total divided by area gives a per-square-metre figure for comparing quotes.
• Hard works only: Furniture, appliances and soft furnishings are outside this estimate.

How to use it

1. Floor area: Enter built-up area. Convert it yourself if you only have usable area.
2. Unit price: Enter the hard-construction rate per square metre, and keep it consistent with what the material share covers.
3. Materials share, Labour share: Both are percentages; whatever is left falls under other costs.
4. Contingency: Enter a share of the total. It is added separately and is not buried inside the materials figure.
5. Check the total: Press Calculate and add materials, labour, other costs and contingency against the budget total. Shares above 100 are refused.

Things to keep in mind

• Area basis: Area is built-up; convert usable area yourself.
• Unit price scope: Keep the per-square-metre rate consistent with what the material share includes.
• Share total: Material, labour and other shares above 100 are rejected.
• Contingency scope: Contingency is a share of the total and is not inside materials.
• Scope of estimate: Only hard construction is estimated; furniture and appliances are extra.

The per-square-metre rate and the three shares have to describe the same scope. If the rate already includes main materials, adding a large materials share double-counts them. Contingency is applied to the total and printed as its own row, so it can be removed or adjusted without disturbing the split between materials, labour and other costs.

A 90 square metre flat at 1200 per square metre gives 108000 in base cost before the shares are applied. If that 1200 already includes main materials, entering a 45 percent materials share on top of it counts those materials twice. Declare the scope of the unit price once and keep the three shares consistent with it for the whole estimate.