← Amazon FBA vs FBM calculator
Sellers search this after Amazon asks them to enroll a SKU and the 5% or 10% clip looks cheap next to a $29.99 list price. The discount is only half the hit. Referral is charged on the price the enrolled buyer actually pays. Fulfillment, inbound, and storage do not get cheaper because the unit is on a standing discount. Unlike a coupon, there is typically no per-redemption fee.
Open the Amazon FBA calculator, keep your own list price and fee preview, and enter the Subscribe & Save percent and the share of units you expect to enroll. The table below uses the page defaults: $29.99, 15% referral, large-standard FBA at $4.15, $8.00 cost of goods, $1.20 inbound, one month of storage, 80 units, 30% target margin, 40% enroll.
At list the unit keeps $10.99 (36.7%) and hits the 30% target. 5% S&S drops the buyer to $28.49. Referral falls with that price and profit is $9.72 (34.1%). That still hits the target. The same 5% coupon would leave $9.12 because of the $0.60 redemption fee.
Only some buyers enroll. If 40% of 80 units take 5% S&S (32 units), this month keeps $838.68 against $879.46 at list — $40.79 less. About 4.2 new S&S-only sales offset those converted buyers. A 15% promo on this listing leaves $7.17 (28.1%) and misses the target.
| Offer | Buyer pays | Profit | vs list | Margin |
|---|---|---|---|---|
| List price | $29.99 | $10.99 | $0.00 | 36.7% |
| 5% S&S (1 item) | $28.49 | $9.72 | −$1.27 | 34.1% |
| 10% S&S (5+ items) | $26.99 | $8.44 | −$2.55 | 31.3% |
| 15% S&S (promo) | $25.49 | $7.17 | −$3.82 | 28.1% |
If the discounted unit itself loses money — an 80% S&S clip on this example — more enrolled deliveries make the month worse, not better. The calculator reports that as no offset volume. A still-profitable discount can be held with a handful of new subscribers; enter the enroll share you actually expect and the page compares that mixed month to the all-list month.
This models a seller-funded discount, the conservative case. If Amazon funds the discount on your settlement, leftover matches list — type 0%. Rates change by category, size, season, and account. This page does not publish Amazon’s live Subscribe & Save or fulfillment schedule. Enter the numbers from your current fee preview. The calculator is arithmetic, not advice, and it does not claim enrollment will raise conversion or rank.
On the calculator example — a $29.99 home listing, 15% referral, large-standard FBA at $4.15, and $8 cost of goods — list keeps $10.99 (36.7% margin). 5% Subscribe & Save drops the buyer to $28.49 and leaves $9.72 (34.1%). That still hits a 30% target. If 40% of 80 units enroll, the mixed month keeps $838.68 against $879.46 at list, and about 4.2 new S&S-only sales offset those converted buyers.
The same percent usually leaves more than a coupon because Subscribe & Save typically has no per-redemption coupon fee. On this example a 15% coupon leaves $6.57 after a $0.60 fee; 15% S&S leaves $7.17. The calculator models a seller-funded discount. If Amazon funds the discount on your settlement, leftover matches list — type 0%.
No. Fulfillment, inbound, and storage stay the same. Referral is charged on the discounted checkout price, so that line falls. Extra volume can recover a still-profitable discount; it cannot recover an S&S unit that already loses money.