Monthly commerce operating terrainOrder columns share the timeline with cumulative inventory use and contribution
Marketing & Advertising
Shopping Campaign Forecast Calculator
Forecast a shopping campaign as a constrained commerce system. Monthly budget changes with seasonality, CPC follows auction inflation, conversion responds to feed quality and demand, approved orders consume inventory, and contribution retains both fulfillment and advertising costs rather than treating revenue as profit.
12-month approved orders—
Forecast revenue—
Forecast contribution—
Ending CPC—
Inventory used—
First constrained month—
Auction-to-inventory terrain
Follow media cash through auction cost, approved orders, contribution, and sellable stock
| Month | Budget | CPC | Clicks | Conversion | Approved orders | Revenue | Contribution | Inventory remaining |
|---|
How to build the forecast
Connect auction assumptions to sellable stock
- Enter the month-one media budget and approved growth plan.
- Use a starting CPC from a comparable product and market window.
- Separate monthly CPC inflation from budget growth.
- Enter base conversion and only the response attributable to planned feed-quality improvement.
- Reconcile approval, order value, margin, and fulfillment from commerce records.
- Enter sellable inventory and review the monthly ledger for the first constrained month.
Shopping forecast fundamentals
Demand, auction cost, and inventory move on different clocks
Media budget
Monthly cash available to buy shopping clicks.
CPC inflation
Independent change in auction price per click.
Demand seasonality
Monthly response pattern applied to conversion.
Feed-quality response
Entered lift linked to product-data improvement.
Approved demand
Converted clicks retained after approval.
Stock constraint
Point where modeled demand exceeds sellable inventory.
Auction mechanics
More budget can buy fewer incremental clicks when CPC rises
Budget growth and auction inflation are compounded independently. The ledger therefore shows whether planned media expansion increases click capacity or merely pays a higher price for similar traffic.
Feed response
Product-data improvement should have an evidence trail
Better titles, identifiers, images, availability, and categorization can change eligibility and response, but the entered uplift is an assumption. Link it to controlled tests or comparable before-and-after evidence.
Inventory boundary
Forecast revenue stops when sellable units run out
The model caps approved orders at remaining inventory. This exposes the first constrained month rather than allowing media-driven demand to create impossible revenue after stock reaches zero.
Detailed calculation process
Compound the auction path, convert demand, and decrement stock
Monthly budget and CPCBₘ = B₁(1 + g)ᵐ⁻¹; CPCₘ = CPC₁(1 + i)ᵐ⁻¹
Clicks and approved demandKₘ = Bₘ ÷ CPCₘ; Dₘ = Kₘ × CVR × (1 + f) × seasonₘ × a
Stock-constrained ordersOₘ = min(Dₘ, Iₘ₋₁); Iₘ = Iₘ₋₁ − Oₘ
ContributionCₘ = Oₘ × (AOV × margin − fulfillment) − Bₘ
- Bₘ
- media budget in month m; currency
- g
- monthly budget growth; decimal/month
- CPCₘ
- cost per click; currency/click
- i
- monthly CPC inflation; decimal/month
- Kₘ
- purchased clicks; clicks
- CVR
- base click-to-order conversion; decimal
- f
- feed-quality response; decimal
- a
- order approval rate; decimal
- Iₘ
- remaining sellable inventory; units
Default substitution
Month-one clicks = $52,000 ÷ $1.18 = 44,067.80. Before seasonality, adjusted conversion = 3.1% × 1.08 = 3.348%. Approved demand applies the month-one seasonal factor and 91% approval, then cannot exceed 18,500 available units.
Reconciliation: opening inventory minus the sum of approved orders equals ending inventory; monthly revenue and contribution sum exactly to the headline forecast totals.
Planning use
Respond differently to an auction constraint and a stock constraint
When CPC is binding, improve feed relevance, bids, or product mix. When inventory is binding, reduce media, prioritize contribution-rich products, or change replenishment. These are different operating decisions.
Model limitations
The forecast is a portfolio-level operating model
It excludes SKU-level margin and stock, replenishment lead time, returns after approval, tax, payment lag, competitor shocks, organic cannibalization, attribution uncertainty, and statistical forecast intervals.
Forecast evidence
Inputs that deserve monthly refresh
- Budget and actual platform billing.
- CPC and eligible click volume by product group.
- Backend approval, order value, margin, and fulfillment.
- Sellable stock and planned replenishment.
Key terminology
Shopping forecast glossary
- Cost per click
- Advertising cost divided by purchased clicks.
- Auction inflation
- Entered monthly change in CPC.
- Feed-quality response
- Modeled conversion change tied to catalog improvement.
- Approved demand
- Orders retained after the approval rate.
- Sellable inventory
- Units available to satisfy modeled approved demand.
- Constraint month
- First month where demand exceeds remaining inventory.
- Contribution
- Order contribution after fulfillment and media cost.
Practical examples
Shopping Campaign Forecast Calculator in real planning situations
- Project holiday demand while allowing CPC inflation and order conversion to move differently.
- Find the month where available inventory begins constraining otherwise affordable media.
- Compare revenue growth with contribution after fulfillment and advertising cash are retained.
Important note
Before relying on this result
The forecast excludes SKU-level margin and stock variation, auction shocks beyond entered inflation, returns after approval, taxes, payment lag, competitor response, organic cannibalization, and statistical uncertainty.
Additional Shopping Campaign Forecast Calculator questions
Why forecast CPC and conversion separately?
Auction price and site response have different drivers and should not be hidden inside one ROAS assumption.
How is inventory pressure calculated?
Approved orders are accumulated against entered sellable inventory; the ledger flags demand beyond remaining stock.
Does seasonality affect every variable?
No. It changes the entered demand factor; CPC inflation and feed-quality response are modeled separately.
Are the monthly values a confidence interval?
No. They are a deterministic operating forecast from current assumptions.