Margin Bench / Our approach
Calculation methodology
How inputs, formulas, rounding, numeric limits, and editorial changes are handled.
What the calculation does
The 33 business tools apply explicit formulas to numbers you supply. Numeric tools run locally in the browser, without accounts or remote calculation APIs.
Entering decimal numbers
The shared parseDecimal parser accepts a dot or comma as a decimal separator: 12.5 and 12,5 both mean twelve and a half. Enter numbers without currency symbols, percent signs, thousands grouping, or scientific notation. Leading and trailing spaces are ignored; spaces within a number are not grouping separators.
Ambiguous entries such as 1,234 or 1.234 are rejected rather than guessed. For one thousand two hundred thirty-four, enter 1234. For the decimal one point two three four, enter 1.2340 or 1,2340. Mixed separators such as 1,234.50 are not accepted.
Enter percentage points: 15 means 15%, not 0.15%. Use one currency throughout a calculation; the tools do not convert exchange rates. Match reporting periods and populations, such as monthly revenue and monthly churn for the same paying-customer group.
Rounding and precision
Calculations use JavaScript binary floating-point numbers, not exact decimal accounting arithmetic. Most results are displayed with up to two decimal places; money results show two. Formatting uses English-style separators, and very small displayed values may round to zero. Display rounding does not make the underlying inputs more precise.
Break-even units are rounded upward to a whole unit because a partial unit cannot meet an indivisible sales target. For example, fixed costs of 100 and unit contribution of 30 require four units, not three. Floating-point representation can affect that upward rounding extremely close to an integer boundary. Check such boundaries separately when they matter to an order or production decision.
Limits and undefined results
Numeric inputs must be finite; most are nonnegative, while designated signed inputs accept negative values where the formula allows them. Divisors such as revenue, customers, or ad spend must be positive where required by the formula. Bounded percentages cannot exceed 100, and a counted subset cannot exceed its population in tools such as customer churn and visitor conversion rate. Net revenue retention can exceed 100% when expansion more than offsets losses.
A zero or negative pre-ad contribution has no finite break-even ROAS. Zero monthly churn does not produce a usable infinite LTV estimate. Numeric overflow is rejected; the parser also rejects nonzero decimals too small to remain nonzero in the supported number range. Break-even unit targets beyond JavaScript's safe whole-number range are rejected. These checks do not detect every precision loss, impossible business assumption, or omitted expense.
Negative results can be meaningful even when most inputs are nonnegative. A negative profit is a loss. A negative maximum CAC means the supplied profit target cannot be preserved even with no acquisition spending, not that you should set a negative budget.
Editing and review policy
Formula changes should be considered together with field definitions, example arithmetic, result labels, and limitations. Editorial changes should preserve the distinction between observed inputs and hypothetical assumptions. A correction should change the affected explanation or calculation, not merely refresh a date.
This is an editing policy, not a claim that every page has received independent professional review or that automated checks establish financial correctness. Tool dates describe catalog updates, not certification. If you find an inconsistency, use the contact page and include the tool, non-sensitive example inputs, expected result, and reasoning. Recheck consequential results against your records and an appropriate qualified adviser.