Skip to content
MasterMath

Renovation Cost Calculator

What a renovation costs, adding up your own items and then contingency, professional fees, permits and VAT, with the weight of each trade.

Currency and number format for

Total budget

—

Total budget—
Cost of the works—
Contingency—
VAT—
The most expensive item—
What is not building work—
Base before tax—

Item by item

ItemQuantityPriceAmountShare

How this was worked out

    Indicative result. You enter the prices: we bring no table of our own. A cost per square metre copied off the internet changes by country, by year and by city, and would give you a false budget with the look of a real one.

    The formula

    total = (works + contingency + fees + permits) × (1 + VAT)

    Where it comes from

    What you ask a trade for is the cost of the works, and that is usually where comparing quotes stops. But on top of that figure sit things that are not optional: contingency, which on an older home runs around 10 % and is a certainty rather than a cushion; professional fees and permits where they are needed; and tax on all of the above. Together they come to nearly a third of what you end up paying.

    How to work it out by hand

    1. Enter each item with its quantity and unit price
    2. Add the amounts: that is the cost of the works
    3. Add the contingency percentage, plus fees and permits if there are any
    4. Apply VAT to that base

    What is worth knowing

    Sorting the items by amount rather than by the order they will be done changes the conversation: two or three trades almost always take more than half the budget, and that is where a second quote pays off. On the rest, haggling 10 % moves very little. On contingency, the rule on site is that in a home over forty years old 10 % falls short: the moment a wall is opened or a floor lifted, services appear that nobody had allowed for.

    Frequently asked questions

    How much does it cost to renovate a house?

    It depends entirely on the items and on prices where you live, and you enter both. The page adds them up and includes what usually gets left out.

    How much contingency should I allow?

    10 % is usual, and on an older home it falls short.

    What is the cost of the works?

    The sum of the items: what the builder charges, without tax or professional fees.

    Does VAT apply to everything?

    To the base, which includes the works, the contingency and the fees.