Purchase price variance (PPV) measures the difference between an actual purchase price and a defined standard or expected price, multiplied by the comparable quantity purchased. It helps explain whether purchases cost more or less per unit than the chosen baseline.
For buyers, a related question is whether the supplier invoiced the agreed PO price. Keep that agreement check separate from accounting PPV: a supplier can invoice exactly what you agreed while the purchase still exceeds the accounting standard.
Quick answers
What is the PPV formula? This guide uses (actual unit price − standard unit price) × actual quantity purchased. A positive result is unfavorable: the purchase costs more than the standard. A negative result is favorable. Some systems reverse the subtraction; label favorable or unfavorable rather than relying on the sign alone.
Is the standard price always the PO price? No. The standard is the expected cost defined for the analysis or accounting system. The PO contains the terms of a particular order. Preserve both when you need to measure cost performance and check supplier billing.
Does a favorable PPV prove a saving? No. A lower unit price can come with larger quantities, more freight, lower quality or additional stockholding costs. Evaluate the total buying decision.
Is a supplier’s proposed increase already PPV? It is an early signal of a possible cost change. Keep a proposed change separate from an accepted revision and the actual transaction used in the report.
Formula and a worked example
compares actual and standard prices for the actual quantity purchased. Define the units and cost components consistently on both sides.
PPV = (actual unit price − standard unit price) × actual quantity purchased
Fictional example: the standard is $36 per twelve-bottle case. Eight equivalent cases are purchased at $38 each.
Measure
Calculation
Result
Standard cost for the purchased quantity
8 × $36
$288
Actual purchase cost
8 × $38
$304
PPV
($38 − $36) × 8
$16 unfavorable
PPV percentage
$16 / $288 × 100
Approximately 5.56% unfavorable
The example excludes freight and tax on both sides. If the actual price were $34, the same eight cases would produce a $16 favorable variance.
For a percentage, divide the variance by standard cost for the same quantity. A zero baseline does not support this percentage. For a period total, sum comparable line variances; calculate the overall percentage from total variance divided by total corresponding standard cost, rather than taking an unweighted average of line percentages.
A sum for a quarter is a quarterly total. It is not an annualized figure unless you explicitly make and explain a projection.
Standard price, PO price and invoice price answer different questions
Consider the same fictional eight-case purchase. The accounting standard is $36 per case, but the buyer agrees to $38 before ordering. The supplier invoices $38.
Standard-to-actual comparison: $16 unfavorable. The purchase exceeded the standard.
PO-to-invoice comparison: zero price difference. The supplier billed the agreed price.
Supplier proposal: evidence explaining the change, if retained with the order.
Now suppose the PO remains at $36 and the invoice arrives at $38 without an accepted revision. The buyer has a billing exception to investigate as well as a difference from the standard.
Do not overwrite the original standard every time a supplier changes a price if your purpose is to measure cumulative movement. Maintain dated baselines, record accepted order revisions separately, and agree the standard-cost update policy with the person responsible for accounting.
Keep price and quantity differences separate
Normalize packs, specifications and currency before comparing prices. A ten-bottle case cannot be compared directly with a twelve-bottle case. A substitute may need its own item mapping and baseline.
For an operational PO-to-invoice review, compare the price for matched quantities and investigate unmatched quantities separately. If six cases are invoiced at $38 against a $36 PO price, the price difference on those six cases is $12. Two outstanding cases do not yet create another invoiced price difference.
If eight cases are invoiced but only six received, check partial deliveries, invoice coverage and the supplier’s evidence. Do not silently substitute the received quantity into every report: the accounting transaction and the operational receipt answer different questions.
The three-way matching workflow connects the order, receipt and invoice so the team can investigate both price and quantity exceptions before the appropriate payment decision.
Common causes and what to check
Possible cause
Evidence to inspect
Buyer’s next step
Market or contract price changed
Dated quote, agreement and effective date
Confirm which price applies to this order
An emergency purchase used another supplier
Stockout history, alternatives and delivery need
Review the supply gap as well as the unit price
A volume tier did not apply
Agreed threshold and qualifying purchases
Check whether the quoted tier was earned
A substitute or different pack arrived
Item specification, pack mapping and acceptance
Compare equivalent units or treat it as a different item
Freight or surcharges changed
Invoice lines and cost-allocation basis
Separate item-price movement from delivery costs
The baseline or source data is wrong
Standard version, currency, duplicate lines and credits
Correct the data before drawing a conclusion
An unfavorable result does not establish supplier misconduct or buyer error. External prices, product requirements and an intentionally conservative standard can all affect it. Likewise, a favorable result may reflect a generous baseline rather than better buying.
For supplier conversations, bring the specific item, original agreement, revised terms and invoice. See managing supplier price increases for the broader purchasing response.
Price variance, landed cost and profit
A supplier-item-price comparison is useful when both sides exclude the same additional costs. A landed-cost comparison answers a broader question by including the relevant freight, duties and other costs on a consistent basis. Label which measure you use; adding freight only to the actual side does not isolate an item-price change.
Avoid equating a purchase-price difference with an immediate change in profit. Purchases, inventory, cost of goods sold and variance accounts have different timing and treatment. Confirm how your accounting system records the transaction and handles any remaining inventory before translating an operational report into a margin claim.
A bulk discount also needs a stock decision. Estimate how much extra inventory the purchase creates, how long it will be held, and the associated carrying cost, waste and cash requirement. A favorable price variance alone cannot establish whether buying ahead is worthwhile.
Review changes while the order is still open
A connected purchasing record can make the explanation easier to find:
Retain the original order and the baseline used for comparison.
Keep the supplier’s proposed change beside its source message.
Have the responsible buyer accept, reject or clarify the proposal.
Record what actually arrives, including partial deliveries and substitutions.
Match the invoice to the relevant order and receipt, preserving unresolved exceptions.
That workflow supplies evidence. It does not automatically approve a payment, establish an accounting PPV report or guarantee the correct cost-of-goods-sold entry. Supported supplier channels and accounting handoffs need to be checked for your setup.
Evaluate this workflow in LineNow
Bring one purchase with a changed price and a partial delivery to a LineNow purchasing demo. Ask to see the original PO, supplier reply, accepted revision, receipt and invoice context. Verify how you would retrieve or export the fields needed for your own variance calculation, including its baseline and quantity basis.
