What Seller Fulfilled Prime Actually Is
Seller Fulfilled Prime (SFP) lets you display the Prime badge on your Amazon listings while shipping orders from your own warehouse. Instead of sending inventory to Amazon's fulfillment centers through FBA, you handle storage, packing, and shipping yourself — but you still get that coveted Prime badge next to your product.
Why does this matter? Prime members spend an average of $1,400 per year on Amazon compared to $600 for non-Prime shoppers. When a Prime member filters search results to show only Prime-eligible items (and most of them do), your non-Prime listing simply disappears. The Prime badge alone can increase your conversion rate by 50-100% on competitive listings.
The SFP Trial Period: Where Most Sellers Fail
Amazon doesn't just hand out Prime badges. You need to survive a trial period that lasts anywhere from 5 to 90 days, and the requirements are strict.
During the trial, you need to hit all of these benchmarks:
- Minimum 300 Prime trial orders shipped (this used to be 200 — Amazon raised it)
- On-time shipment rate of 99% or higher — that means 99 out of every 100 orders scanned by the carrier before the ship-by date
- Cancellation rate below 0.5% — cancel more than 1 in 200 orders and you're done
- Valid tracking rate of 99% — every single order needs a real, scannable tracking number
- Use Amazon Buy Shipping for at least 99% of your orders
That 99% on-time shipment rate is the one that kills most sellers. One bad day with a carrier pickup delay, one morning where your printer jams, one weekend where you understaff — and suddenly you're at 98.5% and Amazon resets your trial.
Shipping Speed: The Real Challenge
SFP requires you to offer one-day and two-day delivery to a significant portion of the US population. Amazon measures this based on the customer's delivery date, not your ship date. So if you're based in California, you can't realistically promise two-day delivery to customers in Maine through ground shipping.
Here's what this means in practice:
- You need to ship same-day or next-day for most orders
- Order cutoff times matter — Amazon expects you to ship orders placed before early afternoon the same day
- Weekend delivery coverage is expected, which means Saturday shipping for orders placed Friday
- Your carrier network needs to cover 90%+ of the continental US within the delivery windows
Most sellers achieve this through a combination of USPS Priority Mail (1-3 days), UPS Ground (which hits most of the country in 1-5 days from a central location), and FedEx. If you're only operating from one warehouse on the coast, you'll struggle. Sellers with warehouses in the Midwest or those using multiple fulfillment locations have a massive advantage.
What SFP Actually Costs
Let's break down the real numbers. Say you're selling a $30 product and shipping 500 orders per month.
FBA costs for comparison:
- FBA fulfillment fee (standard size): ~$5.40
- FBA monthly storage: ~$0.87 per cubic foot
- Inbound shipping to Amazon: ~$0.50-1.00 per unit
- Total FBA cost per unit: roughly $6.50-7.50
SFP costs:
- Shipping label (Priority Mail or UPS): $5.00-9.00 depending on zone
- Packaging materials: $0.50-1.50
- Labor (pick, pack, ship): $1.50-3.00 per order
- Warehouse space: varies wildly by location
- Total SFP cost per unit: roughly $7.00-13.50
On pure shipping economics, FBA usually wins. Amazon's carrier rates are hard to beat. But SFP gives you advantages that don't show up on a per-unit spreadsheet: you control your inventory (no stranded inventory nightmares), you avoid long-term storage fees, you can customize packaging, and you don't risk Amazon commingling your products with counterfeits.
Which Carriers Qualify for SFP
Amazon requires you to use their Buy Shipping service, which limits your carrier options to those integrated with Amazon's platform:
- USPS — Priority Mail and Priority Mail Express are the workhorses for SFP
- UPS — Ground, 2nd Day Air, Next Day Air
- FedEx — Ground, Express Saver, 2Day, Standard Overnight
- Amazon Shipping — available in some metro areas, actually quite competitive on pricing
One thing to note: you can't use USPS First Class for SFP orders. It doesn't have guaranteed delivery dates, so Amazon won't accept it for Prime-eligible shipments.
Shipping Software That Makes SFP Manageable
Running SFP manually is a recipe for failure. You need automation to hit those 99% thresholds consistently.
ShipStation is the go-to for most SFP sellers. Its automation rules can automatically select the cheapest carrier that still meets Amazon's delivery deadline for each order. You set rules like "if delivery zone is 1-4, use UPS Ground; if zone 5+, use USPS Priority Mail Express." ShipStation also integrates directly with Amazon Buy Shipping, which is a requirement for SFP.
Veeqo is worth a serious look because Amazon owns it and it's now free. That means tight integration with Amazon's systems, free shipping labels, and it's built specifically around Amazon's requirements. For pure Amazon sellers doing SFP, Veeqo might be the smartest choice right now.
ShipBob works if you want someone else to handle the actual fulfillment. They can act as your distributed warehouse network, shipping from locations close to customers to meet those delivery windows.
When SFP Makes Sense (and When It Doesn't)
SFP makes sense when:
- You sell oversized or heavy items where FBA fees are brutal — think furniture, fitness equipment, or large electronics
- You sell products that need special handling or custom packaging
- You already have efficient warehouse operations with reliable staff
- You're in a central US location that can reach most customers in 2 days via ground
- You have seasonal products and don't want to pay FBA's long-term storage fees
- Your products have low margins and you need to shave costs wherever possible
Stick with FBA when:
- You sell small, lightweight items where FBA fees are reasonable
- You don't have warehouse space or staff
- You sell fewer than 100 units per month (the fixed costs of SFP infrastructure don't make sense)
- You're on the coast and can't consistently meet 2-day delivery nationwide
- You value your weekends (SFP means shipping 6-7 days a week)
Tips for Surviving the Trial Period
Having watched dozens of sellers go through the SFP trial, here's what separates those who pass from those who don't:
Staff up before you start. The trial doesn't care about your excuses. If someone calls in sick and orders ship late, that's on you. Have backup coverage.
Set your shipping cutoff time conservatively. If your carrier picks up at 4 PM, don't set your cutoff at 3 PM. Set it at 1 PM. Give yourself a cushion for the inevitable days when things go wrong.
Batch and print labels early in the day. Don't wait until afternoon to start processing orders. Get everything printed by noon if possible.
Watch your metrics daily. Amazon updates SFP metrics in Seller Central. Check them every morning. If you see your on-time rate dipping below 99.2%, you need to act immediately.
Don't enroll your entire catalog at once. Start with your top 5-10 SKUs. Get those dialed in, pass the trial, then gradually add more products.
Have a backup carrier account ready. If UPS has a service disruption, you need to switch to FedEx or USPS within hours, not days.
The Prime badge is one of the most powerful conversion tools in e-commerce. But SFP isn't for everyone. Be honest about your operational capabilities before committing. A failed SFP trial wastes months of effort, and inconsistent Prime delivery experiences will tank your account health faster than you'd think.