Methodology
Last updated: 27 April 2026
This page explains how NumbKit's calculators work: the formulas behind them, where the data comes from, how often we update, the position we take on automated decision-making, and the limitations you should be aware of. We publish this in the interest of transparency and to comply with Google's Helpful Content guidelines on E-E-A-T.
1. Calculation Approach
All NumbKit tools run 100% client-side in JavaScript. Your inputs never leave your browser. Each calculator implements published, verifiable formulas — no black-box models, no proprietary "secret sauce".
2. Algorithmic Transparency (ADMT)
In compliance with the CCPA/CPRA 2026 amendments and Article 20 of Brazil's LGPD, we declare:
- Our calculators use deterministic mathematical formulas documented on this page
- We do not use artificial intelligence, machine learning, or profiling models to make individual decisions affecting users
- We do not generate credit scores, eligibility judgments, or any automated decision with legal or financial significance over the user
- If you believe a calculator returned an inaccurate result, you have the right to request human review by writing to [email protected]
3. Crypto Tools — Sources & Formulas
CEX-DEX Arbitrage
Net profit = (Sell price − Buy price) × Trade size − (CEX taker fee + DEX swap fee + Gas cost + Slippage estimate). Slippage is estimated using a constant-product AMM model (x·y=k), the standard used by Uniswap v2 and forks.
Impermanent Loss (L2 Pools)
IL is calculated using the closed-form expression for 50/50 constant-product pools: IL = 2·√(price_ratio) / (1 + price_ratio) − 1. Reference: published research on automated market makers from Paradigm and Uniswap whitepapers.
Multi-Leg Breakeven
For a multi-leg strategy with N positions, breakeven price = Σ(entry_price_i × size_i) / Σ(size_i), adjusted for cumulative fees on each leg.
Bridge Fees (Multi-Layer)
Total bridge cost = sum of (origin chain gas + bridge protocol fee + destination chain gas) per hop. Fee structures sourced from public bridge documentation (LayerZero, Stargate, Across) and reviewed quarterly.
Tax-Loss Harvesting
Calculations follow standard short-term/long-term capital gains rules and apply the wash-sale window where jurisdictionally relevant. Always verify against your local tax code before acting.
Market data
Where market data is required (e.g., reference prices), values are pulled at page load from public APIs (CoinGecko, exchange public endpoints). NumbKit does not store these values; they are fetched and discarded within your browser session.
4. Freelance Finance Tools — Fuentes y Fórmulas
Tarifa real por hora
Tarifa real = (Ingreso bruto deseado + Costos operativos + Impuestos estimados) ÷ (Horas facturables anuales). Las horas facturables se calculan descontando vacaciones, feriados, enfermedad y horas no facturables (administración, prospección, capacitación).
Datos regulatorios LATAM (última revisión manual: abril 2026)
- Colombia — UVT 2026: COP $52.374 (fuente: DIAN)
- Argentina — Monotributo Categoría A: hasta ARS $10.277.988,13 anuales (fuente: AFIP, vigente desde abril 2026)
- Chile — Retención boletas de honorarios: 15,25% (fuente: Servicio de Impuestos Internos)
Estos valores son ilustrativos y se basan en la última revisión manual indicada arriba. Dada la inestabilidad normativa de la región, es responsabilidad del usuario verificar los valores actualizados en los portales oficiales (afip.gob.ar, dian.gov.co, sii.cl) antes de realizar liquidaciones impositivas.
IVA en infoproductos globales
Los cálculos consideran las reglas de IVA del país del comprador (B2C) según las normas vigentes en la Unión Europea (régimen One-Stop Shop), Reino Unido, y los regímenes de IVA digital en LATAM (Argentina, Colombia, Chile, México).
Ahorro para jubilación de autónomos
Proyecciones basadas en interés compuesto: FV = P × (1 + r/n)^(n·t) + PMT × [((1 + r/n)^(n·t) − 1) / (r/n)], donde P es capital inicial, PMT aporte periódico, r tasa anual, n períodos por año, t años. Las tasas de retorno por defecto reflejan el promedio histórico de instrumentos balanceados, no recomendación de inversión.
5. Update Frequency
- Tax brackets and regulatory thresholds: reviewed quarterly
- Exchange and DEX fee structures: reviewed quarterly
- Crypto market data (where applicable): fetched at page load from public APIs
- Formulas: reviewed when published research or regulation changes the underlying model
6. Limitations
NumbKit calculators provide estimates, not guarantees. Real-world results may differ due to:
- Sudden market volatility not captured at the moment of calculation
- Regulatory changes between our quarterly reviews
- Exchange-specific promotional fees, VIP tiers, or hidden costs
- Local tax rules that vary by province, municipality, or personal situation
- Smart-contract risk and protocol-specific behaviour on DeFi tools
- L2 sequencer downtime or congestion affecting execution prices
For decisions involving significant amounts of money, always consult a licensed financial advisor, accountant, or tax specialist in your jurisdiction.
7. Corrections and Feedback
If you spot an error in any calculator or in this methodology page, please write to [email protected]. We treat correction requests as a priority and publish revisions within the same week when verified.