Match the price to the unit
A price per pack is different from a price per square metre. A price per board is different from a price per metre of timber. Check how the supplier sells each item before entering the quote. The calculators show each price basis next to its input.
A currency label is not an exchange rate
Choose the currency you are using for all your prices. The site labels totals in that currency and performs no currency conversion. Changing from EUR to GBP changes the label, not the value of your quote. Switching measurements does convert per-area, per-length and per-volume prices to preserve the same physical cost.
Read partial totals carefully
Blank price fields stay unpriced. A known subtotal is not a complete project budget. Check the listed unpriced items, then add preparation, delivery, labour, equipment hire, disposal, taxes not already included and any contingency you choose.
Compare like with like
Request quotes for the same material specification and quantity. Ask whether tax, delivery and pallet charges are included. For aggregates sold by weight, ask the supplier to convert your volume using their actual material density. Keep the final supplier quantity and the assumptions alongside your estimate.