🧮Calculators
Calculators cover finance, health, math, physics, engineering and everyday life: interest and loans, net salary, BMI, rule of three, conversions and more. Results are informational and educational — for important decisions, confirm with a professional and official sources.
2826 tools
Melatonina: Horário de Tomada
Sugere tomar melatonina 2h antes do horário desejado de dormir.
Sleep Debt Calculator
Calculate your weekly sleep debt by comparing the hours you actually slept with your ideal target. Find out how much rest you need to catch up on.
Eficiência do Sono (TST/TIB)
Calcula eficiência do sono: Total Sleep Time ÷ Time In Bed × 100.
Estimador de Gas Fee
Calcula custo de transação ETH: gas usado × gwei = ETH gasto. Mostra também o equivalente em USD.
Tamanho Transação Bitcoin
Estima tamanho em bytes de transação Bitcoin: ~10 + (148·inputs) + (34·outputs).
Lucro Mineração por kWh
Calcula lucratividade diária: (hashrate · preço por TH) − (consumo · custo kWh · 24).
Contagem Regressiva Halving Bitcoin
Calcula dias até o próximo halving do Bitcoin (estimado abril 2028).
Block Reward Bitcoin por Ano
Mostra o block reward (BTC por bloco) com base no número de halvings ocorridos até o ano informado.
ERC-20 Transfer Cost Calculator
Estimate the cost of an ERC-20 token transfer (about 65k gas) on the Ethereum network. Enter the gas price and see the total in ETH and US dollars.
IPv6 Subnet Calculator
Calculate how many hosts and subnets fit in an IPv6 prefix (/n). A tool for network administrators planning IPv6 addressing.
TCP Bandwidth-Delay Product
Calcula o produto largura×atraso (BDP) — tamanho ideal do window TCP para utilizar 100% do link.
Calculadora MTU por Encapsulamento
Calcula MTU efetiva removendo overhead de Ethernet, PPPoE, IPSec, GRE.
MSS a partir de MTU
Calcula MSS (Maximum Segment Size) = MTU − 20 (IP) − 20 (TCP) = MTU − 40.
TCP Window Scaling Factor
Calcula fator de window scaling necessário para suportar uma janela TCP grande (>64KB).
IPv4 Subnet Host Count
Calcula número de hosts utilizáveis em uma subnet IPv4: 2^(32-prefix) − 2.
CIDR Network Calculator
Calculate the network address, broadcast, mask and host range from an IP in CIDR notation. An essential tool for network and subnet administration.
Data de Retenção de Dados
Calcula data limite de retenção: data inicial + anos de retenção pelo propósito.
Distância Sol-Terra (AU)
Calcula distância Sol-Terra em UA pela data (aproximação por excentricidade orbital).
Velocidade Orbital da Terra
Velocidade orbital da Terra em km/s pela data (varia conforme posição na órbita elíptica).
Kepler — Período Orbital
Aplica 3ª lei de Kepler: T² = a³ (T em anos, a em UA).
Distance Modulus to Magnitude
Calculate the apparent magnitude of a star from its absolute magnitude and distance. Essential in observational astronomy and astrophysics.
Redshift z → Velocidade Recessão
Converte redshift z em velocidade de recessão (aproximação não-relativística v = c·z para z<<1).
Doppler — Frequência Observada
Calcula frequência observada por efeito Doppler óptico: f_obs = f_fonte · √((c−v)/(c+v)) (aproximação relativística).
Schwarzschild Radius Calculator
Calculate the Schwarzschild radius (event horizon) of a black hole from its mass, using the formula r_s = 2GM/c². Result given in meters.
Dough Hydration Calculator
Calculate dough hydration with baker percentage (water ÷ flour × 100). Essential for getting bread, pizza and sourdough just right.
Alimentação do Fermento Natural
Calcula quantidade de farinha e água para alimentar fermento natural na razão escolhida.
Salmoura por % de Sal
Calcula quantidade de sal em salmoura (% do peso da água) e tempo recomendado por kg.
Porção de Macarrão por Pessoa
Calcula massa seca a cozinhar (100 g/pessoa padrão, 80-120 g ajustável).
Redução de Molho
Calcula o fator e porcentagem de redução: volume inicial → alvo.
Sal por % do Peso da Carne
Calcula sal para tempero seco em 1.5-2% do peso da carne (cura tradicional).
Escalar Receita por Fator
Multiplica uma quantidade de ingrediente por porções alvo / porções originais.
Caffeine by Drink Calculator
Estimate how many milligrams of caffeine you drink per day by adding up coffee, tea, energy drinks and sodas. Pick the type and the number of servings.
Tempo de Preaquecimento de Forno
Estima minutos para preaquecer forno doméstico (≈10 min para 200 °C, escala linear).
De Broglie Wavelength Calculator
Calculate the De Broglie wavelength of a particle from its momentum (λ = h/p). Key to understanding wave-particle duality in quantum physics.
Heisenberg Uncertainty Calculator
Calculate the Heisenberg uncertainty principle: from the position uncertainty, get the minimum momentum uncertainty (or vice versa). A pillar of quantum physics.
Photon Energy Calculator (E=hf)
Calculate the energy of a photon from its frequency using the Planck equation (E = h·f). Fundamental in quantum physics, optics and spectroscopy.
Photon Momentum Calculator
Calculate the momentum of a photon from its energy (p = E/c). A fundamental concept in quantum physics and radiation pressure.
Partícula na Caixa — Energia
Calcula energia E_n = n²·h² / (8·m·L²) para uma partícula em poço infinito.
Schrödinger — Níveis em Caixa
Lista os primeiros 5 níveis de energia da partícula em caixa 1D em unidades de E₁.
Bohr Radius Calculator
Calculate the Bohr orbit radius for the hydrogen atom with the formula r = n²·a₀, where a₀ is the Bohr radius (≈ 5.29×10⁻¹¹ m).
Fórmula de Rydberg
Calcula λ pelo Rydberg: 1/λ = R·(1/n₁² − 1/n₂²) com R = 1.097×10⁷ m⁻¹.
Wien's Displacement Law Calculator
Calculate the peak wavelength of a black body using Wien's displacement law from temperature. Find the dominant color of stars and hot objects.
Blackbody Peak Frequency (Wien)
Calculate the peak frequency of blackbody radiation with Wien law (f_max ≈ 5.879×10¹⁰·T) from the temperature in kelvin.
UK VAT Calculator (20%)
Calculate UK VAT (the 20% standard rate) on a net or gross amount. Add the tax to a price or break out the VAT already included.
MwSt Alemanha 19%
Calcula imposto sobre valor agregado da Alemanha (Mehrwertsteuer 19%).
France VAT (TVA) Calculator
Calculate French VAT (TVA at 20%) on any amount and see the price with and without tax. Handy for shopping, invoices and business in France.
Spain VAT (IVA) Calculator
Calculate the standard Spanish VAT (IVA at 21%) on any amount and see the total with and without tax. Great for shopping, invoices and business in Spain.
Italy VAT (IVA) Calculator
Calculate the standard Italian VAT (IVA at 22%) on any amount and see the price with and without tax. Handy for shopping, invoices and business in Italy.
Canada GST Calculator
Calculate Canadian GST (5% federal) with the option to add provincial tax (PST/QST). See the final price with taxes for purchases and invoices.
Ontario HST Calculator
Calculate Ontario HST (13% harmonized sales tax) on any amount and see the price with and without tax. Great for shopping and invoices in Canada.
California Sales Tax Calculator
Calculate California sales tax (7.25% minimum state rate, excluding local taxes) on an amount. Add the tax or break out what is already included.
Sales Tax New York 4% + Local
Calcula sales tax estadual (4%) + local típico (NYC ≈ 4.5%, MCTD 0.375%).
Australia GST Calculator
Calculate Australian GST (10% tax) on any amount and see the total with and without tax. Great for shopping, invoices and business in Australia.
Singapore GST Calculator
Calculate Singapore GST (9%) on any amount and see the price with and without tax. Handy for shopping, invoices and business in Singapore.
India GST Calculator
Calculate Indian GST by selecting the rate slab (5, 12, 18 or 28%) and see the total with and without tax. Great for shopping, invoices and business.
NPV (Net Present Value) Calculator
Compute project Net Present Value (NPV) from a cash flow series and discount rate. Decide if a project adds value (NPV > 0).
IRR (Internal Rate of Return) Calculator
Find IRR of a cash flow via Newton/bisection. Also displays NPV at the solution point.
MIRR (Modified IRR) Calculator
Compute Modified IRR (MIRR) using a finance rate for negative flows and reinvest rate for positive flows.
Simple Payback Calculator
Show in how many periods the initial investment is recovered by cumulative cash flow (undiscounted).
Discounted Payback
Payback considering time value of money: each flow is discounted before accumulating. More conservative than simple payback.