Methodology
Break-even Sales Planner methodology
Educational only: Business decision support, not accounting, tax or legal advice.
Privacy: Calculations run locally; Margin101 does not receive your commercial inputs.
Update policy: Reviewed when formulas or official dependencies change.
Scope: Market-neutral small-business planning using your own assumptions.
1. Formulas and units
c = P โ VWhere
- P
- price excluding indirect tax (currency units/unit)Source: Business record
- V
- variable cost (currency units/unit)Source: Business record
- c
- contribution per unit (currency units/unit)Source: Calculated output
m = c รท PWhere
- P
- price excluding indirect tax (currency units/unit)Source: Business record
- c
- contribution per unit (currency units/unit)Source: Calculated output
- m
- contribution margin (decimal)Source: Calculated output
U = (F + T) รท cWhere
- F
- fixed costs (currency units/period)Source: Business record
- T
- target profit (currency units/period)Source: User decision
- c
- contribution per unit (currency units/unit)Source: Calculated output
- U
- required units (units)Source: Calculated output
- Uโ, Vโ, Fโ, T
- season units, variable cost, fixed costs and annual target profit (units, currency units/unit and currency units/year)Source: User assumption
R = (F + T) รท mWhere
- F
- fixed costs (currency units/period)Source: Business record
- T
- target profit (currency units/period)Source: User decision
- m
- contribution margin (decimal)Source: Calculated output
- R
- required revenue (currency units/period)Source: Calculated output
- Uโ, Vโ, Fโ, T
- season units, variable cost, fixed costs and annual target profit (units, currency units/unit and currency units/year)Source: User assumption
U๐ = โUโWhere
- U
- required units (units)Source: Calculated output
- U๐
- operational whole units (units)Source: Calculated output
R๐ = U๐ ร PWhere
- P
- price excluding indirect tax (currency units/unit)Source: Business record
- U๐
- operational whole units (units)Source: Calculated output
- R๐
- whole-unit revenue threshold (currency units/period)Source: Calculated output
A = ฮฃ(Uโ ร (P โ Vโ)) โ ฮฃ(Fโ)Where
- P
- price excluding indirect tax (currency units/unit)Source: Business record
- Uโ, Vโ, Fโ, T
- season units, variable cost, fixed costs and annual target profit (units, currency units/unit and currency units/year)Source: User assumption
- A, W, D
- annual operating profit, weighted contribution and additional units to target (currency units/year, currency units/unit and units)Source: Calculated output
W = ฮฃ(Uโ ร (P โ Vโ)) รท ฮฃ(Uโ)Where
- P
- price excluding indirect tax (currency units/unit)Source: Business record
- Uโ, Vโ, Fโ, T
- season units, variable cost, fixed costs and annual target profit (units, currency units/unit and currency units/year)Source: User assumption
- A, W, D
- annual operating profit, weighted contribution and additional units to target (currency units/year, currency units/unit and units)Source: Calculated output
D = (โ(ฮฃ(Fโ) + T) รท Wโ โ ฮฃ(Uโ)) โจ 0Where
- T
- target profit (currency units/period)Source: User decision
- Uโ, Vโ, Fโ, T
- season units, variable cost, fixed costs and annual target profit (units, currency units/unit and currency units/year)Source: User assumption
- A, W, D
- annual operating profit, weighted contribution and additional units to target (currency units/year, currency units/unit and units)Source: Calculated output
Money inputs and outputs use the currency selected in the scenario without changing the canonical methodology. Rates, margins, utilisation and buffers are entered as percentages and converted to decimal values for calculation.
2. Worked example
Input assumptions
At 100 currency units price, 60 currency units variable cost, 12,000 currency units fixed costs and 3,000 currency units target profit, contribution is 40 currency units per unit or 40%.
Calculation and outputs
Example
At 100 currency units price, 60 currency units variable cost, 12,000 currency units fixed costs and 3,000 currency units target profit, contribution is 40 currency units per unit or 40%.
- Contribution per unit
- 40.00 currency units
- Contribution margin
- 40%
- Required units
- 375.00
- Mathematical revenue
- 37,500.00 currency units
- Whole-unit revenue
- 37,500.00 currency units
- Seasonal annual operating profit
- 5,000.00 currency units
- Seasonal weighted contribution
- 53.33 currency units
- Additional seasonal units to target
- 0
The threshold is 375 whole units and 37,500 currency units revenue for the selected period.
Interpretation
Use the whole-unit threshold as the minimum sales capacity needed to cover the entered fixed costs and profit target.
3. Validation and boundary checks
- Required revenue divided by price reconciles to mathematical required units.
- Whole units always round upward to avoid understating the operational threshold.
- A price at or below variable cost returns an unreachable target instead of Infinity.
- Seasonal contribution reconciles from each season before the weighted annual threshold is rounded up to whole units.
4. Assumptions and source classification
- All commercial amounts are user supplied and exclude indirect tax.
- Fixed costs and target profit use the same planning period.
- Price and variable cost per unit remain constant across each scenario.
- Seasonal demand, costs and target profit are user-entered planning assumptions rather than forecasts supplied by Margin101.
This planner has no current policy-data dependency. Its commercial assumptions are user supplied. Registered family-level regression suites exercise the shared business-logic engine and worked-result reconciliation.
5. Limitations
- The model excludes demand response, capacity, step costs, stock, uncertain payment timing, financing availability and income tax.
- The seasonal workflow does not allocate the additional unit threshold across seasons or forecast demand.
- It is educational decision support, not accounting, tax, legal or business advice.
This is educational decision support, not tax, accounting, legal or financial advice. Check the treatment of your actual transactions under the rules that apply to your business and seek qualified advice where appropriate.
6. Update and evidence policy
Registered family-level suites test formula invariants and example reconciliation; the release ledger records that coverage without claiming a separate oracle for every line of public copy. There is no official threshold or benchmark to refresh for this planner. Commercial inputs remain user-supplied because they vary by business and contract.
Change history
- : Initial public release of the planner and methodology after pre-launch calculation, content, source and interaction review.
Related reading
Guides to interpret the decision and its assumptions.
- Break-Even Analysis: Threshold, Not Forecast
Turn unit contribution and fixed costs into a sales threshold, then test whether the required volume and capacity are plausible.
Read guide - Cohort Size and Break-Even
Calculate a whole-learner threshold from contribution and committed cohort cost without predicting enrolment.
Read guide - Break-Even Price vs Target-Margin Price
Compare break-even and target-margin price boundaries on one cost, volume, period and indirect-tax basis without claiming a correct market price.
Read guide - How to Use Margin of Safety in a Small Business
Measure how far planned or actual sales sit above break-even, then test which price, cost or volume assumption makes that buffer fragile.
Read guide