Inventory how-to

What to track in an inventory spreadsheet

Track one row per SKU with on hand, on order, daily sales rate, lead time, safety days, and a reorder point.

Short answer: Track one row per SKU with on hand, on order, daily sales rate, lead time, safety days, and a reorder point. These five numbers let you see at a glance what needs ordering and when, without opening each product page.

Core columns to include

SKU, product name, variant, supplier name, supplier lead time in days, case pack size or minimum order quantity, current on hand, quantity on order, and date that order is due in. These are the facts you need before you can calculate anything.

Columns you calculate

Daily sales rate (units sold over the last 28 days divided by 28 is a reasonable default), days of stock left (on hand divided by daily sales rate), reorder point (daily sales rate times lead time plus safety days), and suggested order quantity. Recalculate these regularly, because daily sales rate drifts as products trend up or down.

Safety days and why they matter

Add a safety days column per supplier or per SKU. Suppliers with unreliable lead times or SKUs with spiky demand need more buffer. Without this column you will keep guessing at reorder timing instead of working from a number.

Keep it supplier-centric

Group or sort by supplier so you can see everything due from one supplier at once. This matters because you want to send one purchase order per supplier, not place five small orders in a week.

Step by step

  1. List every active SKU in its own row, with supplier and lead time next to it.
  2. Add a column for units sold in the last 28 days and divide by 28 to get daily sales rate.
  3. Add on hand and on order columns, and keep them current after every sale and every delivery.
  4. Set a safety days value per supplier based on how reliable their lead time actually is.
  5. Calculate reorder point as daily sales rate times (lead time plus safety days).
  6. Calculate order quantity as daily sales rate times (lead time plus days of cover) minus (on hand plus on order).
  7. Round every suggested quantity up to the nearest case pack or supplier minimum before you order.

Worked example

A store sells a candle at 4 units a day on average. The supplier's lead time is 10 days, safety days is 4, so reorder point is 4 x (10 + 4) = 56 units. On hand is 60 and nothing is on order, so the spreadsheet should flag this SKU once it drops to 56. If the store wants 30 days of cover, order quantity is 4 x (10 + 30) - (60 + 0) = 100 units, rounded up to the nearest case pack of 12, which is 108.

How SteadyShelf helps

SteadyShelf does these calculations automatically per SKU and gives you an order-by date instead of a spreadsheet to maintain, including rounding to case packs and minimums. It does not do per-location breakdowns or bundle tracking, so if you need those in a spreadsheet you will still maintain that part manually.

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

SteadyShelf is launching on the Shopify App Store. Join early access to get the install link first.

Related guides

All inventory how-to guides ยท Inventory glossary

FAQ

Should I track cost price in the spreadsheet too?

Yes, add a cost per unit column if you want to see order value before you send a purchase order. It is not required for reorder timing but it helps you check budget before committing to a quantity.

How often should I update daily sales rate?

Weekly is enough for most stores. Updating more often just reacts to noise, and updating less often misses real shifts in demand.

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.

Get early access