Side Project Profitability Calculator

Side Project Profitability Calculator helps Estimate revenue, conversion value, and rough profit scenarios from traffic or sales assumptions.

Annual taxable income
₩22,047,996
BEP estimate
4 months
Initial investment
₩6,700,000
Monthly opportunity cost
₩1,303,500

Monthly revenue

₩4,545,000

Monthly cost

₩2,582,667

Includes depreciation and opportunity cost

Estimated tax

₩187,660

4.1% effective

Net profit

₩1,774,673

68.7% margin

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Side project profitability calculator guide

This English page translates the Korean side-project profitability calculator and calls calculateSideProjectProfitability. It preserves revenue-source normalization, fixed costs, initial-investment depreciation, opportunity cost, 2026 income tax brackets, BASIC_DEDUCTION, 3.3% withholding behavior, and 12-month trend output.

Revenue and cost normalization

The Korean source supports subscription, one-time sale, advertising, affiliate, and freelance revenue. Subscription revenue applies churn, advertising uses page views divided by 1,000 times CPM, affiliate revenue uses clicks, conversion rate, and commission, and freelance revenue uses project price times monthly projects.

Fixed cost includes hosting, domain, SaaS tools, marketing, and other recurring expenses. Initial development, equipment, and other setup cost are converted into monthly depreciation over the recovery period, so the result can compare a cash-light side project with one that required upfront build cost.

Tax and opportunity-cost treatment

The tax model annualizes revenue and costs. For withholding mode, the source applies the 3.3% freelancer convention by charging 3% income tax plus 0.3% local income tax on annual income. For business modes it uses the 2026 income-tax bracket table after BASIC_DEDUCTION and then adds 10% local income tax on income tax.

Opportunity cost is hours per week times WEEKS_PER_MONTH times an hourly rate. Including it makes the result stricter because a side project that earns cash but consumes high-value time may have negative economic profit.

Break-even and trend interpretation

Break-even starts from negative initial investment and accumulates monthly net profit while applying monthly growth. The function searches up to 120 months and also returns a 12-month revenue, cost, tax, net-profit, and cumulative-profit trend.

Use the output to decide whether the project deserves more marketing, a price increase, automation, or a stop decision. The calculator is a planning model, not a tax filing tool; real filings depend on documentation, deductible expenses, VAT status, and business registration.