If you want the honest answer before you finalise next year’s budget, here it is: forecasting by taking last year’s sales and adding a growth percentage is one of the fastest ways to engineer a cash flow crisis.

This approach assumes the future is a proportional replica of the past. In retail and FMCG, it rarely is. Your historical data is shaped by promotions, supply chain disruptions, price increases, and one-off events that won’t repeat in the same way.

Apply a flat growth rate to a flawed baseline and you’ll either over-order inventory, trapping cash in a warehouse, or under-order and lose shelf space to a competitor.

It happens in boardrooms every Q4. The leadership team looks at the spreadsheet, agrees that 20% growth feels achievable, drags the formula across the next twelve columns, and calls it a plan.

A percentage is not a plan.

Your promotions are distorting the picture

Last year’s sales weren’t a smooth, organic curve. They were shaped by specific promotional mechanics, seasonal pushes, and retailer-driven events that may look very different this year.

Say last October you ran a BOGO promotion with a major supermarket and posted a £200,000 month. Add 20% and you’re forecasting £240,000 for this October. But what if the retailer changed their promotional calendar, or you opted for a softer mechanic instead?

Without that specific campaign, you might sell £100,000. You’ve ordered for £240,000. The excess stock sits in 3PL storage, accumulating fees while it ages.

At Powdr, we build bottom-up models that link forecasted sales directly to your planned promotional calendar and marketing spend, so inventory orders reflect what’s actually planned, not what happened last year. Build a smarter forecast today

Revenue growth and volume growth are not the same thing

Over recent years, most FMCG brands have raised their RRP to absorb soaring raw material and freight costs. That shows up in the revenue line as growth, even when unit volumes are flat.

If you raised prices by 15% last year and sold the same number of units, your revenue grew but your business didn’t. If your supply chain team is then told to order 15% more units based on that revenue figure, you’ll overstock significantly.

Your model needs to separate value growth from volume growth. Treating them as interchangeable is where forecasts quietly go wrong.

Channel mix changes everything about timing

If your business runs across Direct-to-Consumer, Amazon, and physical retail, a single blended growth rate tells you almost nothing useful. Each channel has a completely different cost structure, margin profile, and cash conversion timeline.

D2C might be growing at 40%, but carries significant customer acquisition costs and high return rates. Wholesale might be growing at 5%, but it pays reliably in volume with 60 to 90-day settlement terms.

A shift in channel mix doesn’t just change where revenue comes from. It changes when cash arrives. “Last year plus 20%” says nothing about that.

New products don’t add revenue, they redistribute it

Every growing retail brand wants to launch new products. The assumption is that a new SKU adds incremental revenue on top of the existing range. It almost never does.

If you sell three flavours and launch a fourth, some of your existing customers will simply switch. The customers who bought Lemon will try Peach. If your model applies growth to Lemon while simultaneously forecasting strong launch numbers for Peach, you’re double-counting the same demand.

The result is excess stock sitting in the warehouse past its best-before date, with margin eroding and cash tied up.

Last year’s stockouts are in your baseline too

This is the most quietly damaging trap in historical forecasting. If your supply chain broke down last year, those failures are now baked into the numbers you’re forecasting from.

If your shipment was delayed at port last July and you were out of stock for three weeks, that month might show £20,000 in sales. Add 20% and you’re projecting £24,000 this July. But your actual unconstrained demand could be £80,000.

By anchoring to that suppressed number, you’re systematically under-ordering. You’ll sell out quickly, miss revenue, and hand shelf space to a competitor who had stock.

A professional model accounts for lost sales. At Powdr, we help you adjust your baseline to reflect what you would have sold with stock available, so you’re never forecasting against a number that was always wrong. Stop leaving money on the table

What to do instead

The fix is to forecast from the activities that drive revenue, not from last year’s outcomes. Distribution points, rate of sale, planned promotional mechanics, marketing spend and expected return. Build the forecast from those inputs and the numbers reflect what you’re actually planning to do.

It takes more work upfront. It also means your inventory orders, cash flow projections, and board presentations are based on something real.

“Last year plus 20%” persists because it’s quick. In retail, quick maths leads to expensive mistakes. Your suppliers, 3PL, and retail partners are operating in the complex reality of today. A financial model built on yesterday’s numbers will eventually break under that pressure.

Ready to stop dragging formulas and start forecasting with precision?
Book a call with the Powdr team today