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How to calculate volume, rate & mix effects
This is the practical, worked version of Price-Volume-Mix analysis. Below are the three formulas and a two-product example where the effects reconcile exactly to the total change.
The formulas
Start from the identity Value = Volume × Rate. For each item i, using base (period 0) and new (period 1) figures, and where Base Share is that item's share of total base volume:
The rate and volume effects are computed directly; the mix effect is the residual, which guarantees the three always sum to the total variance. Sum each effect across all items to get the grand total.
Worked example
Two products, Standard and Premium, compared across two years.
| Product | Base Qty | Base Price | Base Rev | New Qty | New Price | New Rev |
|---|---|---|---|---|---|---|
| Standard | 1,000 | $10 | $10,000 | 900 | $11 | $9,900 |
| Premium | 1,000 | $20 | $20,000 | 1,500 | $21 | $31,500 |
| Total | 2,000 | $30,000 | 2,400 | $41,400 |
Total variance = $41,400 − $30,000 = +$11,400. Now decompose it.
1. Rate effect: (New Rate − Base Rate) × New Volume
2. Volume effect: total volume change × base rate × base share
Total volume grew by 2,400 − 2,000 = 400 units. Base shares are 50% each.
Intuition: 400 extra units sold at last year's average rate of $15 ($30,000 ÷ 2,000) = $6,000.
3. Mix effect: the residual
The blend shifted toward Premium (from 50% of units to 62.5%), so more of the mix sits at the higher $20 rate, a positive mix effect of $3,000.
Reconciliation
| Effect | Amount | % of change |
|---|---|---|
| Volume | +$6,000 | 53% |
| Rate | +$2,400 | 21% |
| Mix | +$3,000 | 26% |
| Total variance | +$11,400 | 100% |
The three effects add up to the exact total change, the property that makes VRM safe to put in front of leadership.
Hierarchical mix
Real analyses rarely stop at two products. When you nest attributes, brand → product → size, the mix effect can be decomposed at each level (brand mix, then product mix within brand, and so on), with every level rolling up to a grand total that still reconciles. Doing this by hand in a spreadsheet is where PVM gets painful; it's exactly what a tool automates.
Skip the spreadsheet. Volume / Rate / Mix runs these formulas across any hierarchy in your browser. Your data stays on your computer. Upload a file and get the full bridge instantly.