Synthetic price floors: ten invented products, two below their floor

What this example is

Everything here is synthetic. The products, costs, prices and rates are invented, and the example shows how the arithmetic works. It is not a pricing recommendation and does not show what any real product should cost.

The script and its output

The script uses whole pence only, a payment fee of 2.5 percent plus 20 pence, a returns allowance of 3 percent and a minimum margin of 20 percent. It was run on Node.js on 12 October 2026 and printed exactly what is shown. Two rows are below their floor: a cushion cover priced 19 pence under, and a gift bundle priced when its parts cost less.

If the matrix is wider than the box, scroll horizontally to read every column. Keyboard: focus the matrix and use Left/Right.

// Synthetic example. All names, costs and prices are invented. Money is in pence (whole numbers).
const FEE_PCT = 25;        // 2.5% payment fee, in tenths of a percent
const FIXED_FEE = 20;      // 20p fixed fee per order
const RETURNS_PCT = 30;    // 3.0% returns allowance, in tenths of a percent
const MARGIN_PCT = 200;    // 20.0% minimum margin, in tenths of a percent
const KEEP = 1000 - FEE_PCT - RETURNS_PCT - MARGIN_PCT;   // 745 out of every 1000

// floor = (landed cost + fixed fee) / 0.745, rounded up to the next penny, using whole numbers only
const floor = cost => Math.floor(((cost + FIXED_FEE) * 1000 + KEEP - 1) / KEEP);
const gbp = p => (p / 100).toFixed(2).padStart(7);

const products = [
  ['T100', 'Canvas tote', 410, 1299],
  ['M101', 'Enamel mug', 520, 1099],
  ['C102', 'Linen cushion cover', 880, 1190],
  ['W103', 'Wool throw', 2150, 3995],
  ['S104', 'Candle, small', 310, 650],
  ['S105', 'Candle, large', 690, 995],
  ['N106', 'Notebook A5', 180, 450],
  ['P107', 'Pen set', 340, 599],
  ['L108', 'Clay planter', 760, 1099],
];
// A bundle's cost is the sum of its parts' costs. Its price was set before the parts' costs rose.
const bundle = ['B109', 'Gift bundle (tote, mug, notebook)', 410 + 520 + 180, 1499];
products.push(bundle);

let below = 0;
console.log('sku   name                               cost   price   floor    gap  status');
for (const [sku, name, cost, price] of products) {
  const f = floor(cost), gap = price - f, bad = gap < 0;
  if (bad) below++;
  console.log(`${sku}  ${name.padEnd(34)} ${gbp(cost)} ${gbp(price)} ${gbp(f)} ${((gap < 0 ? '-' : '+') + (Math.abs(gap) / 100).toFixed(2)).padStart(6)}  ${bad ? 'BELOW FLOOR' : 'ok'}`);
}
console.log(`rows read ${products.length} = below floor ${below} + clear ${products.length - below} + unchecked 0`);

// Printed on 12 October 2026:
// sku   name                               cost   price   floor    gap  status
// T100  Canvas tote                           4.10   12.99    5.78  +7.21  ok
// M101  Enamel mug                            5.20   10.99    7.25  +3.74  ok
// C102  Linen cushion cover                   8.80   11.90   12.09  -0.19  BELOW FLOOR
// W103  Wool throw                           21.50   39.95   29.13 +10.82  ok
// S104  Candle, small                         3.10    6.50    4.43  +2.07  ok
// S105  Candle, large                         6.90    9.95    9.54  +0.41  ok
// N106  Notebook A5                           1.80    4.50    2.69  +1.81  ok
// P107  Pen set                               3.40    5.99    4.84  +1.15  ok
// L108  Clay planter                          7.60   10.99   10.47  +0.52  ok
// B109  Gift bundle (tote, mug, notebook)    11.10   14.99   15.17  -0.18  BELOW FLOOR
// rows read 10 = below floor 2 + clear 8 + unchecked 0

What was and was not exercised

Exercised: the floor arithmetic, the rounding up, the check against a price and the reconciliation of rows read, below floor and clear, by running the script. Not exercised: real costs, real fees, marketplace rules, taxes or any price change in a store. Your own rates, rounding and bundle rule may differ.