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Methodology

Business Budget & Profit Forecast methodology

This planner rolls twelve monthly operating assumptions through base, upside and downside profit scenarios while keeping profit distinct from cash.
Duc Nguyen X.By Duc Nguyen X.Ā· Founder, Margin101Last reviewed: View update historyMethodology

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

Monthly revenue
Rā‚˜ = (Uā‚˜ Ɨ Pā‚˜ + Oā‚˜) Ɨ Sā‚˜ Ɨ (1 + Ī”Rā‚›)

Where

Uā‚˜
unit volume in month m (units/month)Source: User assumption
Pā‚˜
unit price on the selected tax basis (currency units/unit)Source: Business record
Oā‚˜
other revenue (currency units/month)Source: Business record
Sā‚˜
seasonality factor (ratio)Source: User assumption
Ī”Rā‚›
scenario revenue change (decimal)Source: User decision
Rā‚˜
monthly revenue (currency units/month)Source: Calculated output
Monthly variable costs
Vā‚˜ = (Uā‚˜ Ɨ Qā‚˜ + Eā‚˜) Ɨ Sā‚˜ Ɨ (1 + Ī”Vā‚›)

Where

Uā‚˜
unit volume in month m (units/month)Source: User assumption
Qā‚˜
variable cost per unit in month m (currency units/unit)Source: Business record
Eā‚˜
other variable costs in month m (currency units/month)Source: Business record
Sā‚˜
seasonality factor (ratio)Source: User assumption
Ī”Vā‚›
scenario variable-cost change (decimal)Source: User decision
Vā‚˜
monthly variable costs (currency units/month)Source: Calculated output
Monthly gross contribution
Gā‚˜ = Rā‚˜ āˆ’ Vā‚˜

Where

Vā‚˜
monthly variable costs (currency units/month)Source: Calculated output
Rā‚˜
monthly revenue (currency units/month)Source: Calculated output
Gā‚˜
monthly gross contribution (currency units/month)Source: Calculated output
Monthly operating profit
Ī ā‚˜ = Gā‚˜ āˆ’ Fā‚˜ āˆ’ Xā‚˜

Where

Gā‚˜
monthly gross contribution (currency units/month)Source: Calculated output
Ī ā‚˜
monthly operating profit (currency units/month)Source: Calculated output
Fā‚˜
fixed operating costs (currency units/month)Source: Business record
Xā‚˜
one-off operating costs (currency units/month)Source: Business record
Cumulative profit
Cā‚˜ = Ī£įµ¢ā‚Œā‚ā€¦ā‚˜ Ī įµ¢

Where

Cā‚˜
cumulative operating profit through month m (currency units)Source: Calculated output
Annual gross contribution
G = Ī£ā‚˜ā‚Œā‚ā€¦ā‚ā‚‚ Gā‚˜

Where

Gā‚˜
monthly gross contribution (currency units/month)Source: Calculated output
G
annual gross contribution (currency units/year)Source: Calculated output
Budget variance to target
B = Ī£Ī ā‚˜ āˆ’ T

Where

T
target annual operating profit (currency units/year)Source: User decision
B
annual operating-profit variance to target (currency units/year)Source: Calculated output
Action gap
A = max(0, T āˆ’ Ī£Ī ā‚˜)

Where

T
target annual operating profit (currency units/year)Source: User decision
A
action gap to target (currency units/year)Source: Calculated output
max
non-negative maximum operator (operator)Source: Calculated output
Cumulative break-even month
Mįµ¦ = minā‚˜{Cā‚˜ ā‰„ 0}

Where

Cā‚˜
cumulative operating profit through month m (currency units)Source: Calculated output
Mįµ¦
first cumulative break-even month (month number)Source: Calculated output
minā‚˜
first matching month operator (operator)Source: Calculated output
Earnings-scenario equity range
Eā‚— = max(0, Nā‚— Ɨ Kā‚— + Sā‚ āˆ’ D); Eā‚• = max(0, Nā‚• Ɨ Kā‚• + Sā‚ āˆ’ D)

Where

Nā‚—, Nā‚•
user-entered low and high maintainable annual earnings scenarios (currency units/year)Source: User assumption
Kā‚—, Kā‚•
user-entered low and high earnings multiples (multiple)Source: User assumption
Sā‚
user-entered surplus assets included in the equity scenario (currency units)Source: Business record
D
user-entered interest-bearing debt deducted from the equity scenario (currency units)Source: Business record
Eā‚—, Eā‚•
earnings-scenario equity range endpoints (currency units)Source: Calculated output
max
non-negative maximum operator (operator)Source: Calculated output
Cross-check overlap
Oā‚— = max(Eā‚—, Qā‚—)

Where

Qā‚—, Qā‚•
separate user-entered reference equity range (currency units)Source: Business record
Eā‚—, Eā‚•
earnings-scenario equity range endpoints (currency units)Source: Calculated output
Oā‚—, Oā‚•
overlap endpoints when the two entered ranges intersect (currency units)Source: Calculated output
max
non-negative maximum operator (operator)Source: Calculated output
Cross-check overlap high
Oā‚• = min(Eā‚•, Qā‚•)

Where

Qā‚—, Qā‚•
separate user-entered reference equity range (currency units)Source: Business record
Eā‚—, Eā‚•
earnings-scenario equity range endpoints (currency units)Source: Calculated output
Oā‚—, Oā‚•
overlap endpoints when the two entered ranges intersect (currency units)Source: Calculated output
min
minimum endpoint operator (operator)Source: Calculated output
Non-overlapping range gap
Gįµ£ = max(Qā‚— āˆ’ Eā‚•, Eā‚— āˆ’ Qā‚•, 0)

Where

Qā‚—, Qā‚•
separate user-entered reference equity range (currency units)Source: Business record
Eā‚—, Eā‚•
earnings-scenario equity range endpoints (currency units)Source: Calculated output
Gįµ£
gap when the two entered ranges do not intersect (currency units)Source: Calculated output
max
non-negative maximum operator (operator)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

The default fixture plans twelve months of unit revenue, seasonal volume, variable costs, fixed costs and a first-month one-off cost.

Calculation and outputs

Example

The default fixture plans twelve months of unit revenue, seasonal volume, variable costs, fixed costs and a first-month one-off cost.

Base annual revenue
939,690 currency units
Base annual gross contribution
523,548 currency units
Base annual operating profit
223,548 currency units
Base budget variance to target
103,548 currency units
Base cumulative break-even month
Month 2
Base action gap
0 currency units
Earnings-scenario equity low
470,000 currency units
Earnings-scenario equity high
810,000 currency units
Cross-check overlap low
500,000 currency units
Cross-check overlap high
800,000 currency units

The engine sums monthly profit and reports the remaining gap to the annual target without calling the result cash.

Interpretation

Use the three scenarios to separate the operating-profit target from the assumptions that must change to reach it.

3. Validation and boundary checks

  • The plan accepts exactly twelve monthly rows and at least one uniquely named scenario.
  • Annual totals equal the sum of the corresponding monthly engine rows.
  • Variable, fixed and one-off costs remain separate classifications.
  • Other revenue and other variable costs remain explicit monthly records and participate in the same seasonality and scenario adjustments as their respective classifications.
  • Negative or non-finite commercial inputs and scenario changes at or below āˆ’100% fail closed.
  • Business-value range endpoints must be ordered; multiples are bounded from zero to 100 and all monetary assumptions must be finite and non-negative.

4. Assumptions and source classification

  • Use one consistent currency and tax basis across all twelve months and scenarios.
  • Revenue is recognised in the planned month; this does not model collection timing.
  • One-off costs are not multiplied by scenario cost-change rates.
  • The business-value module assumes the earnings scenario and independent reference use the same equity, ownership, currency and date basis.

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

  • Operating profit is not closing cash and should not be used as a liquidity forecast.
  • The model excludes tax, depreciation, financing, working capital and balance-sheet movements.
  • The business-value workflow does not normalise earnings, source multiples, choose a recognised valuation method, assess control or marketability, verify the independent reference, or conclude a transaction, tax or professional valuation.
  • It is educational decision support, not accounting, tax, legal or financial 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

  1. : 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.

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