PC Sum (Prime Cost Sum)
A budget allowance included in a quotation for items you have not yet selected, such as tiles, fixtures, or fittings, so the contractor can provide a total price.
A PC sum (prime cost sum) is a placeholder amount included in a contractor’s quotation for materials or products you have not yet chosen. It covers the supply cost of the item only — the labour to install it is priced separately elsewhere in the quote.
How PC sums work
Imagine you are planning a bathroom renovation but have not yet picked your tiles. Your contractor cannot price the project without knowing the tile cost, so they include a PC sum — for example, “$40 per square metre for wall tiles.” This lets them give you a total project price while you continue shopping.
When you eventually choose your tiles:
- If your tiles cost less than the PC sum, the difference is deducted from the final bill
- If your tiles cost more than the PC sum, the difference is added to the final bill
PC sum vs. provisional sum
These two terms are often confused:
| PC Sum | Provisional Sum | |
|---|---|---|
| Covers | Supply of a specific product (materials only) | An entire piece of work (materials + labour) |
| Example | ”$500 for kitchen taps" | "$3,000 for drainage work” |
| Why estimated | Product not yet selected | Work cannot be accurately measured in advance |
Why PC sums matter for your budget
PC sums directly affect your final cost. If a quote includes several PC sums and you choose products that exceed every allowance, your total project cost will increase — potentially by thousands.
To stay in control:
- Ask your contractor what the PC sum is based on (a basic, mid-range, or premium product)
- Start selecting products early so PC sums can be replaced with actual prices before work begins
- Compare PC sum amounts between different quotations — a lower total quote might simply have lower (and less realistic) PC sums
- Include your product preferences in the project specification wherever possible to minimise the need for PC sums