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Clear explanations, practical examples and decision support for finance, energy, everyday life and health.
Our guides explain calculation methods, inputs and typical model limits. They help with understanding and comparison, but do not replace individual financial, tax, legal, energy or health advice.
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Finance
Compound interest: starting capital, return and timeUnderstand compound interest and how capital, return, contributions and time work together.Dividend planning: payouts, yield and incomeUnderstand dividend yield, gross and net payouts, reinvestment, taxes and the risk that income or share prices can change.ETF savings plan: build wealth over the long termETF savings plan explained: monthly contribution, time horizon, return, fees, compound growth and common mistakes with examples and calculator.ETF, savings account or fixed deposit: compare return, safety and availabilityCompare ETF investing, savings accounts and fixed deposits as three investment options by final value, risk, availability, rates and inflation.Extra repayments: shorten the term or lower the paymentPlan extra repayments and understand their effect on balance, interest and term.Financial independence: target wealth, savings rate and withdrawal ratePlan FIRE with realistic target wealth, savings rate, returns and withdrawal assumptions.German home-buying costs: transfer tax, notary and agent feesEstimate German property transfer tax, notary, land-register and buyer-side agent fees so the full cash and financing need stays visible.German labor costs (2026): wages, payroll costs and employer expenseEstimate labor costs with the German 2026 contribution model or a clearly separated custom-overhead scenario.German net-to-gross salary (2026): income and deductionsEstimate take-home pay or a gross-salary range with a clearly limited German 2026 payroll model and official-check guidance.Gross salary conversion: monthly salary, annual salary and hourly wageUnderstand gross monthly salary, annual salary, extra payments and hourly wage.Home budget: purchase price, equity and affordable paymentEstimate an affordable home budget from income, equity, payment and buffers, then test higher interest and running costs.Hourly wage and annual salary: convert hours, days and payConvert between hourly wage and annual salary using working hours and yearly assumptions.Hourly wage: salary, working time and real payCalculate hourly wage using salary, working hours, holidays and real workload.Household budget: income, expenses and financial roomStructure your household budget and identify fixed costs, variable expenses and savings potential.Inflation explained: purchasing power, price increases and real valueCalculate inflation and understand how prices affect purchasing power over time.Insurance check: plan premiums, priorities and possible gapsStructure insurance cost by mandatory cover, core protection, optional add-ons, monthly budget and useful next checks.Lease payment: upfront payment, term and residual valueEvaluate leasing costs including payment, mileage, residual value and total cost.Leasing, financing or cash purchase: compare car cost properlyCompare leasing, financing and cash purchase by total cost, resale value, payment, tied-up cash and cost per kilometer.Mortgage planning: interest, repayment and total costPlan a mortgage realistically and understand monthly payments, repayment and total cost.Property return: rent, expenses and net yieldCalculate property returns realistically including income, expenses, financing and risk.Purchasing power: inflation, income and real valueCompare purchasing power and understand the real value of money over time.Rent or buy: compare costs, equity and time horizonCompare renting and buying fairly across monthly cost, equity, value growth and risk.Repayment planning: balance, loan term and interest costUnderstand how repayment rate, monthly payment and interest affect remaining debt.Retirement gap: income need, pension and savings rateEstimate a retirement income gap and plan savings needs realistically.Return calculation: profit, time horizon and annualized returnCalculate investment returns using profit, time, costs and comparison values.Savings goal: contribution, duration and target amountPlan a savings goal with starting amount, regular contribution and time horizon.Tax class: net income, household model and wage taxIdentify which German tax-class combinations deserve official comparison without presenting an invented net-pay result.Understanding loan costs: monthly payment, interest and total repaymentUnderstand loan costs clearly: how monthly payment, interest rate, term, fees and total repayment work together – with checklist and calculator.
Category
Energy
Apartment heating costs: monthly and floor-area guideCompare apartment heating costs per month, per year and by floor area. Learn what affects heating expenses and which billing assumptions remain local.CO₂ costs with German residential allocationEstimate CO₂ costs with local price assumptions and, where applicable, the explicitly German residential allocation model.Compare heat pump, gas or district heating: cost, subsidy and riskCompare heating systems realistically: annual cost, upfront cost, subsidy, carbon/price risk, contract terms and technical feasibility.Electricity tariff switching: compare savings properlyCompare electricity tariff savings with unit price, base fee, bonus, annual consumption and recurring cost.EV or combustion car: compare cost, energy use and daily drivingCompare electric and combustion cars fairly across purchase cost, energy, maintenance and running costs.Heat pump calculation: electricity use, efficiency and heating costEvaluate heat pump costs using seasonal efficiency, electricity price and heat demand.How to save electricity costs: find power-hungry devicesCut electricity costs with practical checks for appliances, usage patterns, tariffs and realistic savings.International gas usage: kWh, therms, Ccf and heating costEstimate gas use and annual cost with clearly separated metric/UK and US billing models, currencies and conversion assumptions.Plug-in solar economics: when does a small PV system pay off?Plug-in solar pays off through electricity used at the same time it is generated. Generated power is not automatically savings.Save heating costs: reduce consumption and expensesPractical tips to save heating costs: reduce usage, ventilate properly, optimize room temperature, understand fixed costs and calculate heating expenses.Understand solar + heat pump: how well do they really fit?Solar and heat pumps fit technically, but not perfectly in time: heating demand is high in winter when solar generation is low.Understand solar autonomy: how independent can solar really make you?Autonomy is not a return metric. It shows how much demand is covered by PV and battery and how much grid import remains.Understand solar batteries: when does storage really pay off?Understand solar batteries: self-consumption, payback, lifetime value and a clear decision logic.Understand solar battery size: what capacity really fits?Plan solar battery size realistically: usable kWh, PV surplus, evening demand, storage losses and economics.Understand solar EV charging: when does your car really charge from PV?Solar EV charging only works well when surplus, charging time and driving profile match. This guide separates annual PV yield from usable charging energy.Understand solar PV: does your PV system really pay off?Evaluate solar PV realistically: yield, self-consumption, feed-in without battery, grid import, annual value and payback.
Category
Everyday
Age calculator: years, months and days clearly explainedCalculate age accurately and understand years, months, days and reference dates.Date calculation: deadlines, periods and reference datesCalculate calendar-day differences, shift dates and see where deadlines, business days and legal rules need a separate check.Fuel costs: consumption, distance and price scenarioCalculate fuel cost per trip, month, distance unit and optional fuel-price scenario.German vacation entitlement: working days, part-time and remaining leaveCalculate contractual planning scenarios and German statutory minimum leave under sections 4–5 BUrlG.Household Emergency Planner: supplies, water, documents and communicationPlan practical household preparedness for power outages, supply issues, water, medication, documents, communication and local risks.Overtime calculation: time balance, premiums and compensationCalculate overtime with working hours, premiums, time off and payout options.Percentage calculation: share, change and comparisonCalculate percentage shares, changes and comparisons while keeping the base value, direction and percentage-point difference clear.VAT calculation: net, gross and tax rateCalculate VAT from net, gross or tax amounts and keep the reference value, rate, rounding and special rules visible.Working time: calculate hours, breaks and daily schedulesCalculate working time clearly with start time, breaks, end time and total hours.
Category
Health
Basal metabolic rate: energy needs and daily contextUnderstand BMR as an adult resting-energy estimate and see how activity, health context and body composition limit the result.BMI explained: weight, height and health contextUse BMI as an adult screening value and understand how age, growth, pregnancy and body composition limit the result.Calorie needs: BMR, activity and goal planningEstimate adult calorie needs from BMR and activity, with safety limits for low targets and clear exclusions for special cases.