Gross margin bridge: prior period → current
Decompose gross margin change into mix, rate, and volume effects with quantified contributions.
Copy and customize
You are a senior FP&A Analyst producing the following deliverable: gross margin bridge: prior period → current.
Context
- Workflow: Variance Analysis
- Inputs available: {paste the data here}
- Period: {month / quarter}
- Audience: {who reads this}
What to produce
1. The headline takeaway in one sentence.
2. The three things that materially moved the result, with quantified contribution.
3. The one risk or anomaly worth flagging.
4. A short forward-looking note: what to watch next period.
Guardrails
- Use only the numbers provided; do not invent values.
- Cite a row reference for every claim.
- Flag anything you cannot reconcile rather than smoothing it over.
Run it in four steps
- Pull revenue and COGS by product line for both periods, with unit volumes or transaction counts at the same grain.
- Paste it into
{paste the data here}and set the two periods in{month / quarter}. - Run it to decompose the margin change into mix, rate, and volume.
- Confirm the variable-vs-fixed COGS split is consistent across both periods; an inconsistent split shows up as a phantom rate effect.
When to reach for this prompt
Use whenever gross margin moves more than 100bps period over period and the CFO asks "what's driving it." Best for quarterly board prep.
What you can expect back
Gross Margin Bridge — Q1 → Q2
| Starting GM | 74.2% | |
| + Mix effect | +180bps | Enterprise share grew 6pts |
| - Rate effect | -120bps | hosting unit costs +9% |
| + Volume effect | +60bps | better utilization at higher volume |
| = Ending GM | 75.4% |
Net: +120bps. Mix dominates — pull through to renewal motion.
This prompt has real limitations you should understand.
If your COGS isn't split cleanly between variable and fixed, the volume effect will absorb everything else. The decomposition only works when at least 60% of COGS is unambiguously variable.
Variable / fixed split is fuzzy
Hosting that is "variable with volume" usually has step-function commitments hidden inside. The prompt treats it as cleanly variable and absorbs the step into the rate effect — making rate look worse than it is.
Mix attribution needs stable SKUs
If product lines were rebranded, merged, or renamed in the period, the mix effect will absorb a hygiene problem. The prompt has no way to know the SKU was the same product wearing a different label.
Single-period bridges hide trend
A quarter-over-quarter bridge showing +180bps from mix looks great. The same mix shift reversing the next quarter is invisible until you bridge two periods out. Always show a trailing bridge alongside the headline one.
What your data needs to look like
- Revenue and COGS by product line for both periods
- Unit volumes or transaction counts at the same grain
- A consistent split between variable and fixed COGS
See how FinanceOS handles this prompt on real financial data.
Book a 20-minute walkthrough. We’ll run this exact prompt against a sample dataset reconciled through FinanceOS, and show you what changes when the data underneath is right.
Book a walkthrough