Calculator-led
Material Price Jump Calculator
Enter the old price, new price and quantity. See the total difference and whether it is worth asking about.
Difference
GBP 68.00
Worth asking about if this was not agreed or explained.
Hi [rep name], quick one on this invoice. This line was previously GBP 1.42 and has come through at GBP 1.59 across 400 units, which is about GBP 68.00 ex VAT difference. Can you check whether my usual account price has been applied?
What it is for
Built for real merchant paperwork, not generic accounting.
Use this when a line item has moved from quote to invoice, or when the same material suddenly costs more this month.
Works for blocks, timber, insulation, boards, cement and most priced line items.
Handles ex-VAT and inc-VAT totals.
Keeps the next step calm and specific.
Guidance note
Material price jump formula
Reviewed by ConstructionIntel on 14 June 2026.
A material price jump calculation should compare like with like: old unit price, new unit price, quantity and VAT basis. The simple difference is new unit price minus old unit price, multiplied by quantity. If one figure is inc VAT and the other is ex VAT, convert before comparing or the result will exaggerate the movement.
Use the same unit for old and new prices before multiplying by quantity.
Convert VAT basis where needed so inc-VAT and ex-VAT figures are not mixed.
Separate pure unit-price movement from delivery, fuel surcharge and substitution changes.
Use the calculated difference to decide whether the paperwork is worth a line-by-line invoice check.
What happens next
If it looks odd, send the invoice.
You get the £ difference and a short draft message you can send to your rep if it is worth querying.
Send the invoice