How to Compare Multiple Supplier Quotes

Step 1: Write down what you’re buying

Before opening the quotes, write the requirement in one sentence with quantities and scope, such as “40 tonnes of 20mm crushed aggregate and 12 tonnes of washed bedding sand, delivered to site”. Everything else is measured against this. It also stops a quote’s framing from quietly redefining the job.

Step 2: Pick one basis

Choose one unit per item, one GST basis (ex GST if you can claim input tax credits) and one currency. Every quote will be converted to it.

Step 3: Extract every line, with its source

For each quote, list each line item with quantity, unit, rate and amount, and note where it came from (page and line, or sheet and row). Also capture GST treatment, inclusions, exclusions, validity and payment terms. Source references matter when you later need to show someone why you chose a supplier.

Step 4: Normalise

Here is the arithmetic for three synthetic aggregate quotes, each quoting the same requirement differently:

Ridgeline (per tonne, ex GST)
  40 t × $48.50 = $1,940.00   12 t × $52.00 = $624.00
  Delivery 2 × $185.00 = $370.00   Subtotal $2,934.00
  GST $293.40   Total $3,227.40  (10% of $2,934.00 ✓)

Coastal (per kg, inc GST)
  Gravel: $0.0572/kg × 1,000 = $57.20/t inc ÷ 1.1 = $52.00/t ex
          40,000 kg × $0.0572 = $2,288.00 inc ÷ 1.1 = $2,080.00 ex
  Sand:   12,000 kg × $0.0605 = $726.00 inc ÷ 1.1 = $660.00 ex
  Freight: TBA  →  unknown, not zero

Metro (per m³, ex GST)
  25 m³ × $78.00 = $1,950.00
  8 m³ × $70.00 = $560.00, but the quote shows $590.00 (difference $30.00)
  m³ → t needs a density: no tonne comparison without one

If you wanted to test Metro on a per-tonne basis, you would need a density. For example, a hypothetical 1.6 t/m³ gives $78.00 ÷ 1.6 = $48.75 per tonne, and 25 m³ × 1.6 = 40 t. Change the assumption and the answer changes, so confirm it with the supplier and label it.

Step 5: Check specifications, not just prices

Ridgeline quotes “20mm crushed aggregate”, Coastal “drainage gravel 20mm” and Metro “20mm screened stone”. They share a size, not necessarily a product. Until each supplier confirms the product suits your use, treat those lines as conditional matches rather than equivalents.

Step 6: Compare complete scope and list what’s unknown

Add up what each supplier charges for the whole requirement. Where something is unpriced, excluded or not mentioned, leave it as unknown and say so. In this example only Ridgeline is fully priced, so the honest conclusion is “incomplete”: no overall winner yet, with specific questions to send to Coastal and Metro.

Step 7: Ask, then decide

Turn every gap into a question for that supplier: freight price, product confirmation, the $30.00 line difference. Then compare again. Price is one input. Lead time, validity (Coastal’s is 14 days) and payment terms (30 days EOM vs COD vs 7 days) matter too.