freelance-rate-math

A zero-dependency, pure TypeScript minor-unit integer math library for freelance hourly/day rate modeling, reverse take-home netting, self-employment tax adjustments, and contractor capacity planning.

Interactive Workbench: Model your freelance rates with real-time tax and expense sliders on the FastTools Freelance Rate Calculator.

Features

• Zero External Dependencies: Pure TypeScript, zero runtime overhead (<4KB bundle).
• Target Net to Hourly Rate (Reverse Netting): Calculate the exact hourly, day, sprint, and monthly retainer rates required to hit an annual take-home income target after taxes and overhead.
• Hourly Rate to Take-Home Pay (Forward): Break down gross billing projections into estimated tax reserves, overhead coverage, and true net bank deposits.
• Capacity Modeling: Accurately accounts for billable utilization hours, unpaid vacation, sick leave, public holidays, and bench time.
• Dual ESM & CommonJS: Full compatibility with Node.js and browser environments.

Installation

npm install freelance-rate-math
# or
yarn add freelance-rate-math
# or
pnpm add freelance-rate-math

Quick Start

import { calculateFreelanceRates } from 'freelance-rate-math';

// Want $100,000 take-home pay, working 25 billable hrs/week with 6 weeks off?
const result = calculateFreelanceRates({
  currency: 'USD',
  mode: 'target_to_rate',
  targetNetIncome: 100000,
  hourlyRate: 0,
  billableHoursPerWeek: 25,
  weeksOff: 6,
  annualExpenses: 12000,
  taxRatePct: 30, // Federal + State + 15.3% SE tax buffer
  profitBufferPct: 10 // Retirement / cushion reserve
});

console.log(result.hourlyRate);          // $156 / hr
console.log(result.dayRate);             // $1,248 / day (8h)
console.log(result.grossAnnual);         // $179,400 gross billings required
console.log(result.annualBillableHours); // 1,150 billable hours / year
console.log(result.w2ParityMultiplier);  // 1.79x (Contractor rate vs W2)

Interactive Web Utility

Model custom tax brackets, currency switches, and client rate tiers:

👉 FastTools Freelance Rate & Invoice Calculator

License

MIT © Alfaz Mahmud Rizve • Part of FastTools