What the numbers say
Buy two, get one free: the customer pays $80.00 and takes three. Against selling two at full price, the free unit costs $14.10 per order: its unit cost, one more pick, and any change in the label for the extra weight.
Three for the price of two keeps $29.70 per order, against $43.80 for two at full price and $20.65 for one. The offer pays when it turns single-unit buyers into three-unit buyers; given to customers who were buying two, it only costs $14.10 an order.
Per visitor, it earns as much as selling one even if 30.5% fewer visitors buy.
The cost structure, and where it comes from
| Price | $40.00, a bag of coffee. Offer Suite's demo store catalog (offer-suite-demo.myshopify.com, docs/dev-store/catalog.json) |
|---|---|
| Unit cost | $12.00. “Single Bag: price 40.00, unit cost 12.0 · mug gift: unit cost 4.0, compare-at 18.00” Offer Suite's demo store catalog (offer-suite-demo.myshopify.com, docs/dev-store/catalog.json) |
| Pick and pack | $3.20 per order and $0.48 for each extra item. Fulfill.com, 3PL pricing benchmarks (The Fulfillment Advisor 2025 survey of 600+ warehouses), read September 23, 2026 |
| Shipping label | USPS Ground Advantage, commercial, Zone 5, by weight rounded up to the pound: 1 lb $8.74 · 2 lb $9.95 · 3 lb $11.57 · 4 lb $12.84 · 5 lb $13.48. Packed weight is an assumption: 0.8 lb per unit. USPS Notice 123, USPS Ground Advantage Commercial, Zone 5 (effective July 12, 2026), read September 23, 2026 |
| Card fees | 2.9% + $0.30 per order, a common online card rate. Shopify doesn't publish one rate: it depends on your plan and the card. An assumption. |
| Refund reserve | 5%, Offer Suite's default assumption for consumables. NRF's all-category figure for online sales is 19.3%, but consumables are rarely returned; use your own rate. |
| Gift | a mug: unit cost $4.00, retail $18.00. The demo store's mug gift: unit cost $4.00, compare-at $18.00. |
The offer document an agent would write
This is the offer as a document, the way an agent writes it for Offer Suite's API. It validates against the offer schema as it stands. Ids are placeholders, except the coffee ones, which are the demo store's real products; the discount is stated the way the offer states it, and Offer Suite checks with a real cart that checkout charges exactly the prices above.
Show the document offer.json · validates against the offer schema
{
"schema": "offer/1",
"recipe": null,
"identity": {
"code": "PB_COFFEE_BUY_X_GET_Y",
"experience": "pb-coffee-buy-x-get-y-v1",
"campaign": "cmp_playbook",
"presell": null,
"signature": null,
"carrier": {
"cartAttributes": [
"_oe_offer",
"_oe_version",
"_oe_code"
],
"lineProperties": [
"_oe_option",
"_oe_role"
],
"orderTags": [
"offer:PB_COFFEE_BUY_X_GET_Y",
"option:{optionKey}",
"v:{version}"
],
"passthroughKeys": []
}
},
"shop": {
"domain": "offer-suite-demo.myshopify.com",
"market": {
"country": "US",
"currency": "USD"
}
},
"campaignRef": null,
"rulesRef": null,
"selectionMode": "exclusive",
"axes": [],
"picks": [],
"options": [
{
"key": "one",
"label": "Buy 1",
"isDefault": false,
"surfaced": true,
"axisValues": {},
"unitCount": {
"value": 1,
"source": "declared"
},
"fallback": null,
"groupKey": "one",
"lines": [
{
"role": "main",
"quantity": 1,
"required": true,
"bind": {
"resolveBy": "fixed_variant",
"productId": "gid://shopify/Product/15092668957039",
"variantId": "gid://shopify/ProductVariant/53479762788719"
},
"purchase": {
"type": "one_time"
},
"priceSnapshot": {
"price": 40,
"compareAt": null,
"at": "2026-09-23T00:00:00Z"
},
"cogsRef": "cost:variant/53479762788719"
}
],
"pricing": {
"promisedFirstCharge": 40,
"promisedRenewal": null,
"compareAt": {
"value": 40,
"basis": "copy"
},
"shipping": {
"free": false,
"statedValue": null
},
"mechanisms": []
},
"gifts": {
"mode": "inherit"
},
"checkout": {
"mode": "checkout_direct"
},
"economics": {
"retentionRate": null
}
},
{
"key": "three-for-two",
"label": "Buy 2, get 1 free",
"isDefault": true,
"surfaced": true,
"axisValues": {},
"unitCount": {
"value": 3,
"source": "declared"
},
"fallback": null,
"groupKey": "three-for-two",
"lines": [
{
"role": "main",
"quantity": 3,
"required": true,
"bind": {
"resolveBy": "fixed_variant",
"productId": "gid://shopify/Product/15092668957039",
"variantId": "gid://shopify/ProductVariant/53479762788719"
},
"purchase": {
"type": "one_time"
},
"priceSnapshot": {
"price": 40,
"compareAt": null,
"at": "2026-09-23T00:00:00Z"
},
"cogsRef": "cost:variant/53479762788719"
}
],
"pricing": {
"promisedFirstCharge": 80,
"promisedRenewal": null,
"compareAt": {
"value": 120,
"basis": "copy"
},
"shipping": {
"free": false,
"statedValue": null
},
"mechanisms": [
{
"type": "discount_function",
"discountRef": null,
"roles": [
"main"
],
"value": {
"type": "fixed_amount",
"amount": 40
},
"appliesTo": "first_charge"
}
]
},
"gifts": {
"mode": "inherit"
},
"checkout": {
"mode": "checkout_direct"
},
"economics": {
"retentionRate": null
}
}
],
"valueStack": [],
"relatedOffers": [],
"terms": {
"renewalDays": null,
"guaranteeDays": null,
"trialDays": null,
"returnWindowDays": null,
"maxPerCustomer": null,
"subscriptionDiscountPersistence": "first_order_only"
},
"economicsDefaults": {
"retentionRate": 0.7,
"cacTarget": 0,
"minGmPct": 0,
"costProfile": "dtc-us"
}
}