An estimate made from memory is not wrong because memory is dishonest. It is wrong because it averages: last month's rose price, a typical hour, a vase bought in a batch of twelve. A recipe sheet replaces the average with the specific piece in front of you, and it keeps the working visible so the next edit takes seconds.
Start with the flower lines
One row per flower or foliage, with a stem count and a cost per stem. The per-stem figure is the important part: it lets you change a supplier price without re-deriving every total. When a bunch arrives, divide its price by the stems you can actually use — after broken heads and unusable lengths — not by the number printed on the invoice. That single choice keeps waste from being counted twice.
Estimate waste from your own records
Waste percentages in a guide are someone else's shop. The useful number is yours: compare stems purchased with stems sold or used over a few weeks, and let the difference inform the percentage you enter. If you have no records yet, start with a conservative figure and revise it when you do. The calculator applies the percentage to flower cost only, so the number stays about perishables rather than everything on the bench.
Time the work once, then reuse it
Labour is the line most often left at zero, usually because the owner's own hours feel free. They are not free to the business even when no wage leaves the account. Time a few arrangements with a phone stopwatch — conditioning, building, wrapping, cleanup — and use the observed figure for pieces of that shape. Then choose an hourly rate deliberately. The tool multiplies; it does not decide what your hour is worth.
Keep hard goods boring
Vase, foam, ribbon, wrap, card, pins, tag: one combined figure per arrangement is enough for costing. If a vessel is expensive and reused across a range, cost it per piece rather than per arrangement, and keep that decision written down. The sheet should reflect what the piece consumes, not what the shelf holds.
Make delivery visible
A delivery run has a cost whether or not it is charged separately. If you allocate a share to each arrangement, put it in the recipe; if you recover it as a separate fee, leave the recipe at zero and remember that the margin shown excludes it. Either choice is defensible. A recipe that silently ignores the run is not.
Update on invoice day, not quarter end
The maintenance habit is small: when a supplier invoice changes a stem price, open the saved recipe, change that one field, and save it again. Every dependent number follows — $38.48 of cost and $96.21 of suggested retail in the example move together. A sheet that is corrected in the same week as the invoice stays trustworthy; one corrected at quarter end becomes a historical document.
Four arithmetic mistakes worth avoiding
- Mixing markup and margin. Doubling cost is a 50% margin, not 100%. If you want a 60% margin, divide by 0.4.
- Applying waste to everything. Waste belongs to perishable flower cost. Multiplying labour by a waste percentage overstates the cost and hides the real labour figure.
- Forgetting commission. A percentage taken from the retail price reduces the payout, not the cost. Price for the payout you want, not the ticket you quote.
- Comparing tickets of different sizes. A 40-stem piece and a 12-stem piece are not comparable prices. Compare margin and cost per stem, then compare tickets.
Use the sheet at the bench
A costing sheet is most useful when it is physically present. Print the sheet for a recurring arrangement, keep it with the recipe, and write the actual stem count on it when the piece is built. The difference between planned and built is the next thing worth measuring — and it is usually where a margin quietly leaks.
None of this requires software. It requires one page per arrangement shape, updated when prices move. StemCost exists to make that page fast to produce, easy to print and impossible to confuse with a market quotation.
The formulas used here are set out in How it works. For the pricing side — markup versus margin, and commission-adjusted retail — read the pricing guide.