Inventory forecasting for a clothing brand is difficult because every style, color and size creates another decision. The goal is not to predict demand perfectly. It is to make better purchasing decisions with the data available while protecting cash from both stockouts and overbuying.
Forecast at the SKU level
Storewide revenue is too broad for purchasing. Break demand down by style, color and size. A tee can be a bestseller overall while one color or size moves slowly. SKU-level history is the foundation of useful apparel forecasting.
Start with sales velocity
Calculate average units sold per day or week over a relevant period. Adjust for stockouts—if a size was unavailable for half the month, raw sales understate demand. Look at recent velocity alongside longer-term averages so sudden trends do not overwhelm the forecast.
Build size curves from real orders
Do not split units evenly across sizes unless data supports it. Use historical size mix by product category, fit and customer segment. Oversized tops, women’s leggings and unisex hoodies may each have different curves. Our size-run planning guide covers this in more detail.
Include lead time and reorder point
A product with a 90-day production and freight lead time needs much more planning than an item that can be replenished in three weeks. Estimate expected demand during lead time and add a reasonable safety buffer based on volatility and the cost of stocking out.
Separate evergreen products from drops
Evergreen products have more historical data and can often be replenished. Limited collections rely more on analogous launches, waitlists, engagement, preorder data and judgment. Do not use the same forecasting model for both.
Account for seasonality and promotions
Black Friday, holiday shipping cutoffs, summer demand and major product launches can distort normal velocity. Annotate historical data so you know whether a spike came from organic demand, paid spend, a discount or an unusually strong campaign.
Connect inventory to marketing plans
A campaign budget can create demand faster than inventory planning expects. Share upcoming ad spend, creator seeding, email sends and launch calendars with operations. Marketing and purchasing should not plan independently.
Watch inventory cover
Weeks of cover estimates how long current sellable inventory will last at the expected sales rate. It is a useful early-warning metric, especially for core SKUs. But it should be interpreted alongside inbound inventory and lead times.
Protect cash from slow-moving inventory
More inventory is not automatically safer. Excess units consume cash, storage and markdown capacity. Use a separate plan for slow movers instead of repeatedly discounting the entire store. The broader principles in how much clothing inventory to order still apply.
Build a simple forecast
- Current sellable units by SKU.
- Recent adjusted weekly sales.
- Expected demand during lead time.
- Known promotions and launches.
- Inbound purchase orders.
- Safety stock based on volatility.
- Target reorder date.
Forecasting improves with repetition. Review forecast versus actual after every major launch or reorder, document why the miss happened, and update the assumptions instead of treating forecasting as a one-time spreadsheet exercise.