Amazon vs Shopify Profitability: The Real Math Behind Each Channel

Founders constantly ask: "Should I sell more on Amazon or push harder on Shopify?" The answer depends entirely on the math, and the math is usually badly understood. Amazon hides costs in 14 different fee buckets. Shopify hides them in apps, ad spend and shipping. Below, the same product run through both channels with every cost surfaced.

Amazon's fee stack (FBA, 2026)

• Referral fee: 8–17% of sale price depending on category (most categories = 15%).
• FBA fulfillment fee: $3.50–$15+ per unit by size/weight tier.
• Monthly storage: $0.78–$2.40/cu ft (peak Q4 hits $3.30+).
• Long-term storage surcharge: kicks in after 271 days.
• Returns processing fee (apparel, shoes, accessories from 2024).
• Inbound placement fee (since 2024).
• FBA inventory reimbursement / aged-inventory fees.
• PPC ad spend (true cost — not the "ROAS" Amazon shows you).
• Coupon clip fees ($0.60 per redemption).
• Vine, brand registry, and other "optional" costs.

Shopify's cost stack

• Subscription: $39–$2,300/month (Basic to Plus).
• Payment processing: 2.4–2.9% + $0.30 (Shopify Payments) or higher with third-party gateway plus 0.5–2% Shopify fee.
• Apps: typical mature store runs $300–$2,000/month.
• 3PL or in-house fulfillment: $4–$10+ per order plus storage.
• Outbound shipping (you pay, even if "free" to customer).
• Returns shipping & processing.
• Meta + Google + TikTok + Klaviyo + creators ad spend.
• Discounts/promos baked into pricing.

Worked example: $59 small home product

Amazon (FBA)

Sale price: $59 · Referral 15%: −$8.85 · FBA fulfillment: −$5.45 · Storage allocation: −$0.40 · Returns reserve: −$1.20 · PPC allocation (ACoS 22%): −$12.98 · Landed COGS: −$11 · Coupons/promo: −$2.10 → Contribution per unit: $17.02 (28.8%)

Shopify (DTC)

Sale price: $59 · Discount: −$5 · Net price: $54 · Payment fee 2.9% + $0.30: −$1.87 · 3PL pick/pack: −$4.50 · Shipping: −$8.20 · Returns reserve: −$1.50 · App allocation: −$0.45 · Landed COGS: −$11 · Ad spend allocation (MER 2.6x): −$20.77 → Contribution per unit: $5.71 (9.7%)

On the same product Amazon delivers ~3× the contribution per unit because Amazon supplies the customer for an effective "rent" of ~37% of revenue, while Shopify forces you to acquire that customer yourself at much higher all-in cost.

When Shopify wins anyway

• High repeat purchase categories (consumables, beauty refills, supplements): the second purchase has near-zero CAC, lifting LTV well above Amazon.
• Strong brand with 60%+ direct/organic traffic: ad spend allocation drops dramatically.
• Customer-data ownership: enables email, SMS, subscription, customer service that Amazon blocks.
• Higher AOV via bundles, subscriptions, customizations.
• Margin protection: control of pricing, no algorithmic price wars.

When Amazon wins

• First-purchase categories with low repeat (gifts, single-use items).
• Branded keyword volume that converts at 10%+ — let Amazon do the conversion work.
• Products that are too expensive to ship one at a time at DTC volumes.
• Cash-cycle constrained brands: Amazon pays every 14 days regardless of which day you advertised.

How to actually decide

• Build a fully loaded P&L per channel for your top 10 SKUs.
• Compute contribution per unit AND contribution per dollar of working capital tied up.
• Assess strategic value: customer data, repeat rate, brand equity.
• Look at cash conversion cycle per channel — Amazon's is much shorter.
• Most brands above $5M end up at 60/40 or 70/30 splits between channels, not 100/0.

The right answer is rarely "all Amazon" or "all Shopify". It is the SKU-level allocation where each channel earns the inventory it deserves. That is the analysis we run first with every multi-channel client.