Purchase price analysis: compare quotes and buying history

Purchase price analysis compares buying history and current supplier offers on a consistent product, quantity, and commercial basis. It gives procurement evidence for a price review while keeping changes in order size, specifications, and delivery terms visible.

Define a useful comparison group

Choose a reviewed item or equivalent product group, location, quantity band, supplier, and period. State whether prices include freight, rebates, tax, and other charges. Keep the original unit and amount alongside the comparable fields so the buyer can trace the result.

Federal price-analysis guidance recognizes historical prices as a comparison technique but requires adjustments for material differences in terms, quantities, and economic factors. That is a useful discipline for a company buyer. It does not mean a past invoice automatically establishes a fair current price.

The supplier pack-size comparison guide owns unit normalization. Resolve those conversions first; this review starts with prices already expressed in equivalent individual units.

Export the purchasing evidence

Use one row per invoice line, with invoice and line identifiers, purchase-order reference, supplier ID, item, site, invoice date, quantity, unit, net amount, currency, and any linked credit. Keep the order quantity as well when discount eligibility depends on the order rather than the invoice shipment.

Select one transaction population. Purchase orders show commitments, receipts show delivery, and invoices show billing; adding all three amounts together repeats the same purchase. Reconcile the chosen invoice amount to the source export before grouping it.

Bring dated quotes separately, including expiration, minimum quantity, delivery terms, and the exact specification. The federal quotation-evaluation guidance identifies competitive quotes and prior purchases as evidence for price reasonableness. Here they support a buyer's review rather than replacing commercial judgment.

Work the history by supplier and quantity band

An Illinois manufacturer reviews identical machined brackets. The table shows all relevant purchases for the example. Every amount excludes tax and freight consistently, and there are no rebates or returns. Each invoice represents a complete order. The review defines the small band as 1–199 units and the large band as 200 units or more.

With the displayed columns in A:G, calculate the unit price in E2:

=IF(D2>0,F2/D2,"")

Assign the quantity band in G2:

=IF(D2<=0,"Review",IF(D2<200,"Small","Large"))

Keep zero or negative quantities in an exception review rather than assigning an ordinary buying band. Credits need a link to the purchases they adjust.

Weighted purchase price = Comparable net purchase amount / Comparable purchased quantity

For a selected period in J2, supplier in K2, and band in L2, calculate the comparable group's price:

=IFERROR(SUMIFS($F$2:$F$7,$B$2:$B$7,J2,$C$2:$C$7,K2,$G$2:$G$7,L2)/SUMIFS($D$2:$D$7,$B$2:$B$7,J2,$C$2:$C$7,K2,$G$2:$G$7,L2),"")

An empty result means the group needs review; it does not mean the purchase price is zero. Retain full precision and display unit prices to four decimals for period totals and percentages to two decimals.

The group price-change formula is =CurrentPrice/PriorPrice-1. Total quantities and buying proportions are unchanged in this example, so the total price increase is also the spending increase: $10,250 − $10,100 = $150, or 1.49% of $10,100.

The groups reconcile independently: $1,000 + $4,500 + $4,600 = $10,100 in Q1, and $1,050 + $4,650 + $4,550 = $10,250 in Q2. Divide each period's amount by 1,100 units to reproduce its weighted price.

Compare a current offer without rewriting history

Alder now quotes $9.05 per bracket for a 500-unit order on the same reviewed terms. That offer costs 500 × $9.05 = $4,525. Against its Q2 large-order purchase of $4,650, the difference is $125, or 2.69% lower.

Against Alder's Q1 large-order price, however, the offer remains 0.56% higher: $9.05 / $9.00 − 1. Both statements are true. Name the baseline whenever presenting a price opportunity, and describe it as a scenario until a purchase occurs.

For a complete comparison including minimums and freight, use price comparison analysis. For actual versus approved standard cost, use purchase price variance; do not silently substitute that benchmark here.

Use the review to ask better questions

Alder's small and large orders both increased, while Beacon's large orders decreased. Procurement can ask whether the suppliers changed material surcharges, production terms, or discounts. Finance can confirm the amount basis, and the responsible buyer can confirm equivalence.

If buying proportions change in the real export, a company average can move while individual comparable prices stay fixed. The price-volume-mix guide owns that broader decomposition. Keep this report focused on reviewed purchase groups and their evidence.

Where it goes wrong

• Quantity bands are too broad. A large band may combine materially different discount tiers. Refine it using actual commercial terms.
• Last price becomes universal truth. An expedited or obsolete purchase may be an unsuitable baseline.
• Credits fall in another period. Keep linked adjustments visible so timing does not manufacture price movement.
• Averaging row prices. Different invoice quantities require an amount-over-quantity calculation.
• Missing terms disappear. An attractive quote without a comparable freight or specification basis remains an exception.

Review your purchase history in Covirage

Bring your invoice-line export and dated supplier quotes, or a Google Sheet with those fields. Covirage maps the columns; its tools compute comparable prices and check totals, and the external AI model explains the results with every figure traced to its rows. Create a free Covirage account and bring a sample of your own data.

See Covirage for procurement teams for the purchasing context.