The mistake
A row's label is typed text. Its formulas are whatever was there when the row was copied. Nothing ties the two together, so a row can say three bottles and compute two.
It happens when tiers are edited after the table is built. A tier is relabelled instead of rebuilt, a row is inserted and only some of its cells are fixed, or the quantity lives in the label while a different one sits in a hidden column.
A worked example
A row labelled "3 bottles, 10% off each". Its price cell is right: $102.48 plus $9.29 shipping. Its cost cells were copied from the two-bottle row above and still multiply by two.
The row shows costs of $43.04 and a margin of $68.73, or 61.5%. Three bottles cost $55.20 to buy, pick, ship and charge, and the order keeps $56.57, or 50.6%.
| Line | The sheet, costed for two | Three bottles |
|---|---|---|
| Customer pays, with shipping | $111.77 | $111.77 |
| Unit cost | −$20.94 | −$31.41 |
| Pick, pack and label | −$12.97 | −$14.66 |
| All costs | −$43.04 | −$55.20 |
| Margin | $68.73 | $56.57 |
| Margin % | 61.5% | 50.6% |
The order's figures are computed by the margin engine in Offer Suite's own code, in whole cents. The sheet's are the same order with the mistake applied.
What it does to the decision
The sheet overstates this tier by $12.16 an order. A team that sees 61.5% on its three-pack has room, on paper, for a deeper discount or a gift, and gives away margin that was never there.
When a take mix is simulated on a table like this, the error spreads. Shares meant for one tier are multiplied by another tier's economics, and the blended figures are wrong with no single cell to blame.
What prevents it
In an offer document an option has no label apart from its contents. Its lines state the product and the quantity, and the price, the cost and the cart are all derived from those lines. Change the quantity and all three change together.
The real-cart check closes the loop. The cart Offer Suite builds for an option holds the quantities the document states, and each line is compared with the offer, priced exactly as the buy box shows it.
A spreadsheet is still the right tool for some of this. Where it is, and where it stops: Offer Suite vs a spreadsheet.
Where the numbers come from
The example is not a real brand's offer. Every input is sourced below, or marked there as an assumption.
| Price | $37.95, a bottle of supplements. Nature's Sunshine homepage, read 23 September 2026 |
|---|---|
| Unit cost | $10.47. Nature's Sunshine, fourth quarter and full year 2025 results, read 23 September 2026 |
| 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. |
| 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 23 September 2026 |
| Shipping label | USPS Ground Advantage, commercial, Zone 5, by weight rounded up to the pound: 1 lb $9.29 · 2 lb $10.50 · 3 lb $12.12 · 4 lb $13.89 · 5 lb $14.53. Packed weight is an assumption: 0.5 lb per unit. USPS Notice 123, USPS Ground Advantage Commercial, Zone 5 (effective 4 October 2026), read 13 October 2026 |
| Card fees | 2.9% + $0.30 per order: Shopify Payments' online rate for a standard card on the Basic plan in the United States. Higher plans pay a lower rate, and premium cards a higher one. Shopify's pricing page for the United States, online standard card rates, read 12 October 2026 Rates by plan and country |