I tried three inventory apps before admitting the obvious: at my scale, the apps were slower than a spreadsheet. Each one wanted barcodes, SKUs, and syncs with marketplaces I did not use. What I actually needed was to know four things on any given day — what I own, what it cost, how fast it moves, and what is stuck. Ten minutes every evening answers all four. Here is the exact routine, no software required.

The Five Columns That Matter

One tab, one row per lot, five working columns. Everything else is decoration:

  • Lot — what it is and where it lives, in plain words. "Plush 6-sets, shelf B2."
  • In cost — what you paid per unit, landed. If shipping was free, it is just the unit price.
  • Units left — updated at every pack-out. Not a live count; an honest one from yesterday.
  • Listed price — your current ask.
  • Week sold — units moved in the last seven days, the single most diagnostic number in the sheet.

Two formula columns do the thinking: units-left times in-cost equals cash tied up, and week-sold divided by starting units gives you a weekly sell-through rate. Color-fill anything under 10% weekly sell-through red. That red row is your evening's one decision.

The Ten Minutes, Step by Step

The routine only works if it is boring and fixed. Mine runs like this:

  • Minutes 1-3: update units-left for everything shipped today. If nothing shipped, this takes thirty seconds.
  • Minutes 4-6: update week-sold. Sunday evening I archive the week and reset the counter, so trends stay comparable.
  • Minutes 7-8: scan the red rows. One price move, one bundle decision, or one "hold and ignore" note per red row — decided tonight, not "sometime."
  • Minutes 9-10: check inbound. What is ordered, what is due, what needs shelf space cleared before it lands.

That is it. The discipline is not the spreadsheet — it is doing it daily so no update ever takes longer than its slot. Skip three days and the sheet becomes archaeology, and archaeology is where tracking systems die.

What the Red Rows Teach You

Tracking pays for itself the first month, because slow stock stops being a feeling and becomes a number. My recurring findings, yours will differ:

  • Price cuts work, but slowly. Dropping a slow lot 15% typically doubles weekly sell-through within ten days. Deeper cuts move it faster but train buyers to wait.
  • Bundles rescue singles. The slow 30% of one lot often clears in a week once bundled with a fast mover. Our bundling guide covers the mechanics.
  • Cash tied up is the real enemy. The column I check first is no longer profit — it is total cash sitting in unsold units. That number is the budget for the next good lot.

None of this required an app. It required knowing which units had stopped moving — which is a five-column spreadsheet's whole job.

Adapt It for Bulk and MOQ Buying

Buying wholesale lots adds one wrinkle retail arbitrage does not have: MOQs mean you sometimes hold more depth than one selling channel can clear. The fix is a second tab with your lot economics before you buy: units, cost, MOQ, expected weekly velocity at target price, and the number of weeks to clear. If weeks-to-clear exceeds eight, either negotiate the MOQ down or pass.

Real examples with real numbers. A 7000-plus-unit cleaning kit lot at $1.40 is effectively unlimited depth — you buy only what your velocity says you can clear, and the sheet proves out the weekly rate before you reorder. A 960-unit keychain lot at $2.50 with a 100-piece MOQ is a single-decision buy: the MOQ is small enough that even a slow outcome ties up modest cash. A 1000-plus-unit pruning shears lot at $2.20 with a 30-unit MOQ sits in between — deep stock, tiny test size, so the spreadsheet decides your first order and every reorder after. Depth discipline is what keeps tracking simple; buy lots sized to your real velocity and the spreadsheet stays boring — which is the goal.

Two Habits That Keep the Sheet Honest

The spreadsheet fails in two predictable ways, and both have one-line fixes. First: estimating instead of counting. The moment you type what you think is left, the sheet becomes fiction with formatting. Count at pack-out — the label printing step tells you exactly what left, so units-left updates from evidence, not memory. Second: hiding lots you are embarrassed about. Every reseller has the box they overpaid for in March and quietly stopped looking at. It still goes in the sheet, red fill and all — that red row is the cheapest education in sourcing you will ever buy, and it only teaches if it stays visible.

A third habit, smaller but compounding: keep a one-line note column for context. "Bundle candidate with X." "Price tested 12/10, no move." Six months later, when a similar lot appears in a supplier's feed, those notes are the difference between repeating a mistake and dodging one. None of this requires discipline beyond the daily ten minutes — the habits ride on the routine you already have.

When to Actually Upgrade to Software

Spreadsheets fail at three thresholds, and it is worth knowing them in advance. Multi-channel sync — when you list on three marketplaces and oversells start happening weekly, manual counts cannot keep up. Multi-user — the moment someone else packs orders, shared live access beats a file. And multi-location — two storage sites means the "where it lives" column stops being trivial. Until one of those three bites you, software is a subscription for problems you do not have.

Until then, the spreadsheet plus the daily ten minutes is the whole system. If you are building out the rest of your operation, the POR explainer pairs with the sell-through column here, and the bin store sourcing guide covers where a lot of this inventory originates. The full Seller Tips archive has the operational pieces in one place, and the How to Order page covers MOQ and ordering basics before your first lot.

Frequently Asked Questions

Google Sheets or Excel?
Either works. Sheets wins if you want to update from your phone at a flea market; Excel wins on formula speed with thousands of rows. The routine matters more than the tool.

Should I track inventory value at cost or at expected sale price?
At cost, always. Expected-price columns breed optimism, and optimistic inventory sheets are how dead stock hides for a year. Sale price lives in the listed-price column, where it can be argued with.

How do I count stock that lives in FBA?
One row per FBA lot, units-left synced weekly from the seller dashboard. Keep it in the same sheet — the whole point is one place that answers "what do I own."

What is a good weekly sell-through rate?
Above 15% weekly means healthy; 8-15% means watch it; under 8% for three straight weeks means act — reprice, rebundle, or move it. Numbers beat vibes because vibes do not compound.