Purpose
Decompose a period-over-period change in gross or operating margin into its underlying levers — volume, price, mix, cost, and efficiency — and quantify how much each contributed in dollars and margin points, so finance and strategy teams can explain exactly why profit moved and where to intervene. Replaces hand-waving "margin was down on volume" narratives with a defensible, fully-reconciled profit bridge.
When to Use
Invoke this skill when the user asks to:
- Explain why gross margin or operating margin changed vs. prior period, budget, or forecast
- Build a profit bridge or margin waterfall (PVM — price/volume/mix — analysis)
- Decompose P&L variance into its underlying drivers
- Identify which product lines, segments, or SKUs are dragging margin
- Quantify the dollar impact of a price change, volume shift, or cost inflation
- Prepare a board or exec narrative on margin performance and required actions
Inputs Required
Before starting, collect:
- Comparison basis: What two states are being compared (actual vs. budget, this year vs. last year, actual vs. forecast) and the periods involved
- Revenue detail: Units sold and average selling price by product/line/segment for both periods (or total revenue with as much breakdown as available)
- Cost detail: COGS and/or operating costs, ideally split into variable vs. fixed and by category for both periods
- Margin figures: Reported gross margin and/or operating margin (dollars and %) for both periods
- Mix dimension: The dimension along which mix matters (product, channel, geography, customer segment)
- Known events: Any one-off items, reclassifications, price actions, or structural changes in the period
- Intervention threshold: What size of variance (dollars or margin points) is considered material and warrants a flag
If cost isn't split into variable vs. fixed, treat all COGS as variable for the bridge and note the limitation. If units and price aren't available, run a simplified rate/volume bridge on revenue and note reduced precision.
Instructions
Step 1: Reconcile the Endpoints
Before decomposing anything, anchor the bridge:
- State the starting margin (Period 1) and ending margin (Period 2) in both dollars and percent
- Compute the total margin delta to be explained — this is the number every lever must sum back to
- Confirm the total delta before proceeding; the completed bridge must reconcile to this figure exactly (rounding aside)
Step 2: Isolate the Volume Lever
Quantify the margin impact of selling more or fewer units at the prior margin structure:
- Volume effect = (Units₂ − Units₁) × Unit contribution margin₁
- Hold price, mix, and cost constant at Period 1 levels — volume answers only "what did the change in quantity do?"
- Compute per product/segment where unit data exists, then aggregate
- Flag whether volume was the dominant driver or a rounding contributor
Step 3: Isolate the Price Lever
Quantify the margin impact of selling the same units at different prices:
- Price effect = (Price₂ − Price₁) × Units₂
- This captures realized price/rate changes: list price moves, discounting, promotional depth, contract repricing
- Separate stated price actions from realized price erosion (discount leakage) where the data allows
- Note price actions that were taken but not realized — a signal of discounting or leakage
Step 4: Isolate the Mix Lever
Quantify the margin impact of a shift in what was sold, independent of total volume:
- Mix effect = Σ [(Actual unit share₂ − share₁) × Total units₂ × (Margin per unitₚ − Weighted-avg margin per unit₁)]
- Mix isolates the effect of the sales blend shifting toward higher- or lower-margin products/segments
- Positive mix = shift toward premium/high-margin offerings; negative mix = shift toward low-margin volume
- Call out the specific products/segments driving the mix swing
Step 5: Isolate the Cost Lever
Quantify the margin impact of changes in unit cost and cost structure:
- Variable cost effect = (Unit cost₂ − Unit cost₁) × Units₂ — captures input inflation, supplier changes, yield loss
- Fixed cost effect = Fixed cost₂ − Fixed cost₁ — captures absorption, headcount, overhead changes
- Split cost inflation (rate) from cost efficiency (usage) where the data supports it
- Attribute cost movements to categories (materials, labor, freight, overhead) so the intervention target is clear
Step 6: Isolate the Efficiency Lever
Quantify productivity and leverage effects not captured above:
- Operating leverage: fixed cost spread over higher/lower volume (absorption)
- Labor/asset productivity: output per unit of input changing
- Waste, rework, yield, and scrap where measurable
- This is the residual-adjacent lever; keep its definition tight so it doesn't become a catch-all
Step 7: Reconcile and Bridge
Assemble the full waterfall:
- Start: Period 1 margin → +/− Volume → +/− Price → +/− Mix → +/− Cost → +/− Efficiency → End: Period 2 margin
- Confirm the sum of all levers equals the total delta from Step 1
- If a residual remains, label it explicitly as "Unexplained / Other" — never silently absorb it into a lever
- Express each lever in both dollars and margin points of the total move (e.g., "Price contributed +$2.4M, +180 bps of the total −60 bps swing")
Step 8: Flag Outliers and Prescribe Intervention
For any lever or segment breaching the materiality threshold from intake:
- Direction & magnitude: Is it helping or hurting, and by how much
- Root driver: The specific product, cost category, or pricing action behind it
- Persistence: One-off vs. structural/recurring
- Recommended action: A concrete lever-specific move (e.g., "renegotiate freight contract — $1.1M of the cost drag is freight rate," "arrest premium-line volume decline driving −90 bps of negative mix")
- Rank flagged items by dollar impact, largest first
Output Format
- Structure: Endpoint reconciliation → six lever sections (Volume, Price, Mix, Cost, Efficiency, plus residual) → a full margin bridge waterfall → ranked outlier/intervention list
- Length: 900–1,300 words
- Format: Prose analysis with an embedded bridge table showing each lever's dollar and bps contribution; outliers as a ranked list
- Sections: Endpoint Reconciliation → Lever-by-Lever Decomposition → Margin Bridge (table) → Flagged Outliers & Recommended Actions → One-line executive summary of the dominant driver
- Tone: FP&A director — precise, reconciled, action-oriented; no narrative that isn't tied to a quantified number
Quality Checklist
Before delivering output, verify:
- [ ] The sum of all levers reconciles to the total margin delta from Step 1 (rounding aside)
- [ ] Any unexplained gap is labeled as a residual — not silently buried in a lever
- [ ] Each lever is expressed in both dollars and margin points (bps)
- [ ] Volume, price, and mix are computed with a consistent, stated hold-constant convention (not double-counted)
- [ ] Every flagged outlier names a specific root driver and a concrete action — not "watch this closely"
- [ ] Outliers are ranked by dollar impact, largest first
Notes
- The single most common error in profit bridges is double-counting volume and mix; keep volume at total-quantity level and let mix carry only the blend shift
- Sequence matters slightly in PVM math — state your convention (typically volume → price → mix → cost) and apply it consistently so the bridge is reproducible
- When variable/fixed cost splits are unavailable, the efficiency lever loses precision; say so rather than overstating confidence
- A clean bridge that reconciles but flags nothing actionable has failed — the intervention list is the deliverable that earns the analysis its seat at the table
How to use this skill
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Installing in Claude Code:
~/.claude/skills/<folder-name>/SKILL.md— auto-loads in every session anywhere on your machine (recommended for skills you'll use across multiple projects)<your-project>/.claude/skills/<folder-name>/SKILL.md— auto-loads only when working in that project (recommended for project-specific skills)
Restart Claude Code or open a new session to register.
Using in Claude.ai, ChatGPT, Gemini, or other AI tools:
- Drag this file into a new chat, or copy and paste its contents
- Send your task or request as your next message — the AI will apply the skill where it fits
For Claude Code skill details: https://docs.anthropic.com/en/docs/claude-code/skills