The numbers.
The caveats.
The next action.
A complete example based on three fictional monthly summaries. Currency: USD. August and September 2026.
| Metric | August | September | Change |
|---|---|---|---|
| Net sales | 12000.00 | 13800.00 | 1800.00 |
| Orders | 200.00 | 230.00 | 30.00 |
| Website sessions | 10000.00 | 11500.00 | 1500.00 |
| Reported costs | 8000.00 | 9700.00 | 1700.00 |
| Net sales per order | 60.00 | 60.00 | 0.00 |
| Orders per 100 sessions | 2.00 | 2.00 | 0.00 pp |
| Sales less reported costs | 4000.00 | 4100.00 | 100.00 |
| Remainder as % of sales | 33.33 | 29.71 | -3.62 pp |
METRIC LETTER — SEPTEMBER 2026 Fictional online-shop demonstration. Not a real client, testimonial or Metric Letter revenue. Currency: USD. Full September compared with full August. August has 31 days; September has 30. Total changes below are not daily-rate comparisons. THE MONTH IN ONE SENTENCE Net sales rose 15%, while supplied costs rose 21.25%; the amount left after those reported costs increased by only $100. KPI COMPARISON Metric August September Change Net sales $12,000 $13,800 +$1,800 (+15%) Orders 200 230 +30 (+15%) Website sessions 10,000 11,500 +1,500 (+15%) Net sales per order $60 $60 $0 (0%) Orders per 100 sessions 2.00 2.00 0.00 percentage points Reported costs $8,000 $9,700 +$1,700 (+21.25%) Sales less reported costs $4,000 $4,100 +$100 (+2.5%) Remainder as % of sales 33.33% 29.71% -3.62 percentage points THREE OBSERVATIONS 1. Sales, orders and sessions all increased by 15%. Net sales per order and the aggregate orders-to-sessions ratio were unchanged. The totals do not establish which channel or campaign produced the additional orders. 2. Reported costs increased faster than sales. The remainder rose from $4,000 to $4,100 while its share of sales fell. This is a signal to inspect the cost categories, not evidence that a particular expense caused the change. 3. The source summaries omit owner labor, overhead and income tax. The $4,100 remainder is not verified profit. No conclusion about profitability is justified until cost coverage is complete. NEXT-MONTH ACTION LIST - Owner: compare the $1,700 cost increase by product, shipping, advertising and processing category using the underlying exports. Check one-off charges and duplicate entries before changing spend. - Marketing lead: compare sessions and orders by consistently defined channel. Mark unknown attribution explicitly. Keep any proposed test separate from causal conclusions about this month. - Bookkeeping owner: list omitted costs and confirm whether dates use cash or accrual treatment. Preserve the same definitions next month; label any changes. SOURCES AND METHODS Source 1: fictional commerce summary, net sales and order counts. Source 2: fictional analytics summary, website sessions. Source 3: fictional supplied-cost summary, reported costs. Normalized source figures and definitions are in sample-input.json; calculated values are in sample-calculations.json. Net sales excludes shipping and sales tax and is after discounts/refunds. Net sales per order = net sales / orders. Orders per 100 sessions = orders / sessions x 100; it is an aggregate ratio, not a deduplicated customer conversion metric. Sales less reported costs = net sales - supplied costs. Relative change = (current - prior) / prior x 100 for positive prior values. A zero or negative prior value is not given a conventional growth percentage. Rate changes are percentage points. REVIEW NOTES This demonstration assumes matched definitions, one currency and complete consecutive months. It does not connect to customer accounts or verify the truth of the supplied figures. No investment, tax or accounting advice. One consolidated revision is included in the paid service.