You don’t need a data science team to forecast inventory. Learn a simple approach using average daily sales, lead time, and a safety bufferâ€"plus how to turn POS history into reorder points that keep shelves full without overbuying.

Inventory mistakes hurt in two opposite ways:

• Stockouts cost you sales, reputation, and staff sanity.
• Overbuying ties up cash, creates waste, and turns your storeroom into a museum.

What most small businesses want is not “perfect forecasting.” They want a simple, repeatable method that gets them 80% of the benefit with 20% of the effort.

This post is that method. No jargon. No scary formulas. Just three numbers you can pull from your POS history and vendor habits.

The three numbers that matter

1) Average Daily Sales (ADS)

Pick a timeframe that reflects reality:

• Fast-moving items: last 14â€"30 days
• Stable items: last 60â€"90 days
• Seasonal items: compare the same season last year (if you have it)

ADS = total units sold ÷ number of days in the window.

If you sell 120 units in 30 days: ADS = 4/day.

2) Lead Time (LT)

Lead time is how long it takes to replenish after you place an order. Use the number you can actually rely onâ€"not the “best case.”

• Local supplier: 2â€"3 days
• Ship-from-warehouse: 5â€"10 days
• Backordered/handmade: 14+ days

If lead time is inconsistent, use the worst normal case (not the extreme disaster case).

3) Safety Buffer (SB)

This is your “sleep at night” stock. It protects you from:

• surprise demand spikes
• supplier delays
• staff miscounts

Start simple: 2â€"7 days of extra demand, depending on how painful stockouts are.

The reorder point formula (simple version)

Reorder Point (ROP) = (ADS Ã-- LT) + (ADS Ã-- SB)

Using our example:

• ADS = 4/day
• LT = 7 days
• SB = 3 days

ROP = (4Ã--7) + (4Ã--3) = 28 + 12 = 40 units

So when your on-hand count hits 40, reorder.

That’s it. You just created a forecast-driven reorder rule.

Make it real: a 30-minute setup you can repeat

Step A: Pick your “Top 25 pain items”

Don’t start with your entire catalog. Start with items that cause real damage when you run out or overbuy.

For restaurants: core ingredients, packaging, and best sellers. For retail: best sellers + items with long lead times. For service businesses: consumables (cleaning supplies, parts, materials).

Step B: Pull sales history from your POS

You need unit sales by item over a time window. If your POS makes this hard, that’s a signal you’re missing a lever that directly affects cash flow.

Step C: Create reorder points

Even a spreadsheet works:

As you mature, you can keep these reorder points inside your inventory system so staff don’t have to interpret spreadsheets during a rush.

Common mistakes (so you don’t learn them the hard way)

• Using revenue instead of units. Reorder points are about units on hand.
• Ignoring shrink/waste. If you regularly lose 2% to shrink, bake it into safety buffer.
• Not accounting for promotions. If you run a sale, temporarily increase ADS.
• Changing the window too often. Update weekly or monthly, not daily.

How a POS helps you protect cash flow

The reason this works is that it turns “gut feeling” into a rule. A good POS makes those rules easy to maintain because it keeps:

• accurate sales history by item
• consistent item definitions (SKUs/variants)
• inventory counts that staff can trust

If you want to start building reorder points with clean sales history, M&M POS is a practical place to begin. Set up your top items, track on-hand counts, and let your day-to-day sales create the history you need to forecast. You can download M&M POS and start smallâ€"then expand inventory tracking as your confidence grows.

Forecasting doesn’t have to be fancy. It just has to be consistent.