Inventory how-to

How to forecast inventory for the holiday season

Holiday forecasting works best when you blend last year's seasonal pattern with your current sales trend, then order earlier than usual because supplier lead times often stretch in that period.

Short answer: Holiday forecasting works best when you blend last year's seasonal pattern with your current sales trend, then order earlier than usual because supplier lead times often stretch in that period. If you do not have a year of history yet, use your recent sales trend and add a safety buffer based on your best guess of the holiday lift.

Start with your baseline

Look at your daily or weekly sales per variant over the last 28 to 90 days. This is your baseline run rate before any holiday lift. Do not use the last few days alone, since that can be noisy for low-volume SKUs.

Layer in last year's seasonality

If you have about 13 months of sales history, compare the same weeks last year against the weeks before the holiday ramp last year. That ratio is your seasonal lift. Apply the same ratio to this year's baseline, variant by variant, since some products spike more than others.

Push order dates earlier

Suppliers often have longer or less reliable lead times around the holidays. Add extra safety days to your normal lead time for this period and recalculate your order-by date from that. Ordering a week or two earlier than your normal reorder point is usually cheaper than running out during peak demand.

Watch new and low-history SKUs separately

New products or recent bestsellers will not have a clean year-over-year comparison. For these, use category-level trends or similar products as a proxy, and round up your safety stock since the forecast is less reliable.

Step by step

  1. Pull 28 to 90 days of sales per variant to set your current baseline.
  2. Compare the same calendar weeks from last year, before versus during the holiday period, to estimate a seasonal lift ratio per variant.
  3. Apply that lift ratio to this year's baseline sales to get a holiday daily sales estimate.
  4. Add extra safety days to each supplier's normal lead time for the holiday period.
  5. Recalculate reorder points and order quantities using the holiday daily sales figure and the padded lead time.
  6. Place orders by the earlier order-by date, factoring in case pack sizes and supplier minimums.
  7. Recheck stock weekly through the season and adjust remaining orders if actual sales run ahead of or behind forecast.

Worked example

Last year, a candle variant sold 4 units a day in early November and 10 units a day in the two weeks before Christmas, a lift ratio of 2.5x. This year the same variant is running at 6 units a day in early November, so the holiday estimate is 6 x 2.5 = 15 units a day. The supplier's normal lead time is 10 days, but you add 5 safety days for the holiday period, giving 15 days total. Reorder point = 15 x 15 = 225 units. If you currently hold 80 units and have 0 on order, order quantity for 20 days of cover = 15 x (15 + 20) - 80 = 445 units, rounded up to the nearest case pack.

How SteadyShelf helps

SteadyShelf applies seasonality automatically once a SKU has about 13 months of history, and lets you add extra safety days per supplier to pull order-by dates earlier for the holiday period. For brand new or low-history SKUs you will still need to estimate the holiday lift yourself and adjust the suggested quantity by hand, since there is no year-over-year data for the app to use.

$29/month flat, unlimited products and suppliers, 30-day free trial. Run the numbers now with the free reorder point calculator.

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FAQ

What if I have no sales history from last holiday season at all?

Use your recent non-holiday run rate as the baseline and apply a manual lift estimate based on your category or past experience, then build in extra safety stock since you are forecasting blind. Track actual sales closely once the season starts so you can reorder fast if you underestimated.

Should I forecast each store location separately for the holidays?

SteadyShelf forecasts at the overall store level and does not do per-location forecasts or transfers, so if you sell from multiple locations you will need to split holiday allocations manually based on each location's typical share of sales.

Let SteadyShelf do this math for every SKU

Order-by dates per supplier, seasonal forecasts and draft POs for your Shopify store. $29/month after a 30-day free trial.

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