5 Numbers Every eCommerce Seller Needs to Know Every Month

Kimberly Green | 2026-04-14

Most ecommerce sellers check revenue once a month and call it financial management. Revenue is a starting point. What actually moves the needle—payroll, reinvestment, whether you're building a real business or burning cash—comes down to five numbers that separate successful sellers from those running in circles. 1. Net Revenue Per Channel (Not Gross GMV) Gross merchandise value tells you nothing about what you keep. If you sold $100,000 on Amazon, but paid Amazon 15% in fees, your seller fees, your cost of goods, your payment processing—you're keeping maybe $40,000 to $55,000. That range matters. Net revenue per channel is what you actually earned after platform fees, payment processing fees, and COGS. Calculate it for every sales channel: Amazon, Shopify, your own website, TikTok Shop, wherever you sell. Why it matters: You can't compare channel performance or decide where to scale without knowing which channels are actually profitable. A high-revenue channel can be a cash sinkhole if fees and COGS eat the margin. Just Pull the Formula Gross revenue by channel (from your accounting software or dashboard) Minus platform fees (Amazon FBA, marketplace commissions, payment processing) Minus COGS for units sold on that channel Equals net revenue per channel Do this monthly. Channel profitability shifts overnight during Q4 or seasonal spikes. You can't wait for quarterly review. 2. COGS as a Percent of Net Revenue If your COGS was $30,000 and your net revenue was $100,000, your COGS ratio is 30%. That's the ratio that actually tells you whether your margins are tightening or holding steady. eCommerce sellers often fixate on product cost per unit. That's procurement; it's not the full picture. When you layer in tariffs, freight, currency fluctuations, duty fees, and shrinkage, your effective COGS shifts. The ratio catches that shift month to month. Why it matters: A climbing COGS ratio signals that your supply chain costs are outpacing revenue growth. You need to either raise prices, negotiate supplier costs, or accept shrinking margins. Knowing the direction early prevents a profit collapse. The 60/30/10 Framework 60% range: COGS at or below 40%, leaving 60% gross profit. Healthy for most product categories. 30% range: COGS climbing toward 45-50%. Margins are tightening. Time to audit suppliers or adjust pricing. 10% range: COGS above 50%. You're not profitable at scale. Fix it or exit the product. 3. Monthly Advertising Spend as a Percent of Revenue Most ecommerce sellers track ad spend. Almost none compare it to revenue—and that blindness costs them. If...