How calculations work
What each free tool does, the assumptions it makes, and where it stops being useful. If something here looks wrong, email monsibdtheadventurer@gmail.com.
Rules that apply to all three
- Blank is not zero. A blank optional field is left out and listed under "not included". A zero you type is counted as zero.
- Currency is a label. The box is printed next to results. Nothing is converted, and no country rates or labor costs are assumed.
- Numbers are plain. Use a period for decimals. Commas are accepted only as thousands separators (1,250). Letters, exponents, and values above 1,000,000,000 are rejected with a message.
- Negative values are rejected wherever a negative makes no sense (costs, quantities, shares).
- Rounding. Results are calculated at full precision and rounded half-up (away from zero) only for display, normally to 2 decimals. A column of rounded lines can differ from its rounded total by a cent.
- Your values stay in your browser. The tool scripts make no network requests, and the site sends a security header that blocks them on these pages. Nothing is stored; reload and the fields are empty.
- Tested. The calculation code is covered by automated tests, including zero, negative, blank, very large, decimal and malformed inputs.
Garment unit-cost estimator
Inputs. Fabric unit (yard, metre, kg or garment), fabric price, fabric used per garment, fabric waste %, trims, labor, printing or embellishment, packaging, overhead (a fixed amount, a percent, or both), quantity, currency label.
fabric = price × amount used per garment
waste = fabric × waste %
direct = fabric + waste + trims + labor + printing + packaging
overhead = fixed amount + (direct × overhead %)
cost per garment = direct + overhead
total = cost per garment × quantity
Assumptions.
- Waste is a percentage added on top of fabric cost (10% waste on 6.00 of fabric adds 0.60). It applies to fabric only. If your supplier or factory quotes yield differently, enter your own equivalent percentage.
- If fabric is priced per garment, the "amount used" box is ignored and the tool says so.
- A fabric price without an amount used (or the other way round) is an error, not a silent zero.
- Overhead is whatever you decide to allocate. The tool has no default and no industry benchmark.
Not covered. Freight, duty, tax, minimum-order surcharges, sampling costs, defect rates beyond fabric waste, exchange rates, and price breaks by quantity.
Retail margin and break-even calculator
gross profit = price − unit cost
gross margin = gross profit ÷ price
markup = gross profit ÷ unit cost
fee per unit = price × fee %
contribution = price − unit cost − fee per unit − other per-unit costs
break-even units = ceil(fixed launch costs ÷ contribution)
Markup is not margin. The same sale gives two different percentages. Converting: margin = markup ÷ (100% + markup); markup = margin ÷ (100% − margin).
| Unit cost | Price | Markup on cost | Margin on price |
|---|---|---|---|
| 20.00 | 30.00 | 50.0% | 33.3% |
| 20.00 | 40.00 | 100.0% | 50.0% |
| 20.00 | 50.00 | 150.0% | 60.0% |
Break-even. Fixed costs divided by contribution, rounded up to a whole unit, because part of a unit cannot be sold. If contribution is zero or negative, no number of sales recovers the fixed costs, and the tool says that instead of printing a number. If fixed costs are blank, break-even is not calculated; if they are 0, break-even is 0. Revenue at break-even is shown as revenue, not profit.
Not covered. Returns, discounts, sales tax or VAT, shipping income or cost beyond what you enter as "other per-unit costs", cash-flow timing, and unit costs that change with volume. Fee percent is capped below 100%.
Size and colour order split planner
Method. Largest remainder (Hamilton). Each row's exact share of the order is quantity × its share ÷ the total of all shares. Every row is rounded down, then the leftover whole units are handed out one at a time to the rows with the largest fractional parts. The units always add up to the order quantity. Ties go to the larger share, then the earlier row. A row with a 0 share never receives a unit.
Worked example. 10 units split 42% / 42% / 16%. Exact: 4.2, 4.2, 1.6. Rounded down: 4, 4, 1 (total 9). One unit is left; the fractional parts are .2, .2 and .6, so the third row gets it: 4, 4, 2.
Totals must add up. Percentages must total 100 (a drift of up to 0.01, such as 33.333 × 3, is accepted and reported). Unit counts must total the order quantity. If not, no split is shown. You can edit the numbers, or tick the option to scale them proportionally; the result then states what was scaled.
Sizes and colours together. Each cell is quantity × size share × colour share, rounded together with the same method, so the whole grid sums to the order. Row and column totals are the sums of rounded cells and can drift from your entered mix by a unit or more; the tool shows the exact share, the grid total and the difference for every row and column.
Not covered. Minimum quantities per size or colour, factory cutting constraints, and any judgement about what mix will sell. The percentages are yours.