Every purchase order is a bet. This tells you how big.

Every purchase order is a bet. Margin tells you whether the bet is positive expected value. Capital exposure tells you the downside if the bet goes wrong. A 35% margin product with $8,000 tied up in slow inventory is a more dangerous position than a 20% margin product with $800 in capital recovering weekly.

The critical shift in thinking: stop asking "what is my margin?" before an order and start asking "how much cash am I putting at risk, and for how long?" A $1,600 order that pays back in 3 weeks has $1,600 of downside for 3 weeks. A $12,000 order that pays back in 9 months has $12,000 of downside for 9 months — plus storage fees accumulating every 30 days while it sits.

The single most predictive question before any PO: "If sell rate drops 50%, how many months does payback take — and can I survive that?" Run the calculator at half your expected velocity. If the answer is uncomfortable, reduce the order quantity before you wire the money.

Capital exposure is why experienced sellers run this calculator at conservative sell rate — not the rate shown on Keepa at the bestseller's peak, not the velocity from the first week after a launch. Model what happens at the 30th percentile of velocity, not the 70th. You live in downside scenarios, not upside ones.

Factories offer volume discounts for a reason: every unit they sell at MOQ locks you into a larger order than you might need. The per-unit cost savings are real — but they come bundled with larger capital commitment and longer payback time. The question isn't "is the discount real?" It's "does the saving justify the additional capital exposure?"

The correct comparison: run this calculator twice — once at the lower MOQ and once at the discounted MOQ. Compare payback time, not just unit cost. A $1.50/unit saving at 500 pieces vs 200 pieces saves $450 total. But if the larger order extends payback from 3 weeks to 14 weeks, that $450 might cost more in opportunity and risk than it saves.

The MOQ trap hits hardest on new products where velocity is unproven. You don't know if this thing will sell 5 or 50 units a week until you've run it for 4–6 weeks. On new products, always choose the smaller initial order even at worse unit economics — you're paying for information, not just inventory. The data from the first small order is worth more than the savings from the discounted large one.

Seasonal products — holiday toys, garden tools, summer gear — face an additional constraint that this calculator must be used carefully around: the effective selling window is shorter than the calendar year. If you're selling a Halloween decoration, you have roughly 6 weeks of peak velocity, a few weeks of shoulder season, and then near-zero for 10 months. Your payback time must fit inside that window or you're carrying dead inventory through an entire off-season.

The seasonal rule: calculate breakeven time at the expected peak sell rate. If payback time exceeds 60–70% of your peak selling window, the order is sized too large. You need to recover capital and ideally sell through during peak season to avoid storage fees on stagnant post-season inventory.

Liquidation math: if an order fails to sell through peak, liquidation is often the right move — even at a loss. The question is whether taking a known loss now is better than continuing to pay storage on unsold units. Run the calculator with a liquidation sell price to see where liquidation breakeven sits. If it's 90% of the order at a steep discount, early liquidation in shoulder season may be cheaper than waiting.

For chronic slow movers — products selling 2–3 units/week that you've held over 90 days — the discipline move is to stop ordering and run down the current stock. Every reorder extends the cash-flow problem. This calculator's verdict for a new PO on a proven slow mover should almost always be no.