金融
ローン、貯蓄、投資、利息などの計算ツール。
Calculators (28)
住宅ローン計算機
毎月の返済額、総支払利息、元利均等償還表、繰り上げ返済効果を詳細にシミュレーションします。
複利計算機
積立投資による資産運用成果を、複利効果・定期拠出・インフレ調整を含めてシミュレーションします。
ローン返済計算機
各種ローンの分割支払額、総利息額、および繰上返済による利息削減効果を計算します。
投資リターン計算機
資産運用ポートフォリオの期待利回り、配当再投資効果、長期資産推移を試算します。
リタイアメント・年金計算機
老後資金の必要額、FIRE早期リタイア達成時期、安全資産取崩し率（SWR）を算出します。
マイカーローン計算機
下取り査定額、頭金、消費税、諸費用を含めた自動車ローンの月額返済額を算出します。
給与・時給換算計算機
年収・月給・日給・時給を就業時間や年間休日数に基づき相互換算します。
所得税・税率計算機
累進課税ブラケットに基づく実効税率、限界税率、税引後手取り額を算出します。
頭金シミュレーター
住宅購入時の頭金比率（LTV）、必要自己資金の積立計画、借入総額への影響を分析します。
ローン借り換え計算機
借り換え手数料を考慮した損益分岐点（ブレークイーブン月数）と総利息削減額を比較します。
VAT Calculator
Calculate Value-Added Tax (VAT), add tax to net amounts, or reverse-calculate pre-tax net prices.
Inflation Impact Calculator
Calculate how compounding inflation erodes your cash purchasing power and compute the future cost of today goods.
401(k)資産運用計算機
退職時の401(k)残高、雇用主のマッチング拠出、複利成長、および月々の退職後収入を計算します。
50/30/20 予算ルール計算機
手取り収入をニーズ（50％）、ウォンツ（30％）、貯蓄・投資（20％）に自動配分して計算します。
年金資産・払出計算機
定期年金の将来価値積立、または退職時の定期受取額（取り崩し計画）を計算します。
実質年率（APR）計算機
事務手数料やローン保証料を含む真の実質年率（APR / IRR）を厳密に計算します。
債券利回り（YTM）計算機
最終利回り（YTM）、直接利回り、マコーレー・デュレーション、価格変動リスクを計算します。
損益分岐点（Break-Even）計算機
固定費・変動費から損益分岐点販売数量、損益分岐点売上高、貢献利益率を算出します。
年平均成長率（CAGR）計算機
幾何平均による年平均成長率（CAGR）、総成長率、および72の法則による倍増年数を計算します。
キャピタルゲイン税計算機
短期・長期のキャピタルゲイン税、投資所得税、および売却後の税引後純利益を計算します。
クレジットカード返済計算機
リボ払い・定額返済による完済期間、累計利息、および最小返済額のコストを計算します。
複数借入返済（アバランチ vs スノーボール）計算機
金利重視のアバランチ法と心理的達成感重視のスノーボール法を比較し、最速完済日を算出します。
DCF法・株式企業価値計算機
将来フリーキャッシュフロー（FCF）とWACC（加重平均資本コスト）から企業の理論株価を評価します。
FIRE（早期リタイア）達成計算機
年次支出と安全資産取崩率（4%ルール）からFIRE目標資産額とリタイアまでの年数を算出します。
将来価値（FV）計算機
初期元本と定期積立金が指定した複利利率で将来いくらに成長するかを正確に計算します。
住宅購入適正予算計算機
年収、手持ち頭金、毎月の他債務返済額から無理のない住宅購入上限価格（28/36ルール）を算出します。
回収期間（ペイバック・ピリオド）計算機
設備投資や新規プロジェクトの初期投資回収年数（単純回収期間および割引回収期間）を計算します。
チップ計算・割り勘計算機
レストランのチップ率、税抜金額に基づくチップ計算、飲食代金の均等割り勘を計算します。
ガイド (28)
Mortgage Math & Amortization: Principal, Escrow & Front-Loaded Interest
Regulation Z monthly fixed amortization equation, PITI escrow breakdown, early interest curves, and PMI dropoff thresholds.
Loan Amortization Mechanics: How Extra Principal Slashes Borrowing Costs
TILA Regulation Z compounding formulas, bi-weekly payment acceleration, extra principal debt reduction, and amortization curves.
Auto Loan Financing: Interest Rates, Loan Terms & True Vehicle Cost
Truth in Lending Act auto amortization equations, sales tax trade-in tax credits, dealer doc fees, and the 20/4/10 affordability rule.
The Mechanics of Compound Interest: Exponential Growth & Time Horizons
Discrete exponential compounding equations, APY conversion formulas, ordinary annuity vs annuity due, and Fisher real inflation discounting.
Investment Returns & CAGR: Measuring Dividends, Growth & Risk
Return on Investment (ROI), Compound Annual Growth Rate (CAGR), DRIP dividend reinvestment, and capital gains taxation drag.
Retirement Horizons & The 4% Rule: Safe Withdrawal Rates Demystified
William Bengen Trinity Study safe withdrawal rates, accumulation compounding, sequence of returns risk, and social security optimization.
Gross vs. Net Pay: Converting Hourly, Biweekly, and Annual Earnings
Fair Labor Standards Act 2,080-hour baseline, overtime time-and-a-half calculation, pre-tax 401(k)/HSA benefits, and FICA withholding.
How Progressive Tax Brackets Work: Marginal Rates vs. Effective Tax
IRS 2024 progressive marginal brackets, standard vs itemized deductions, FICA payroll withholdings, and effective tax rates.
Down Payments and LTV: How Equity Eliminates Private Mortgage Insurance
Fannie Mae / FHA loan-to-value (LTV) risk tiers, Private Mortgage Insurance (PMI) cost elimination at 20% down, and savings timeline modeling.
Mortgage Refinancing Break-Even: Balancing Closing Costs Against Monthly Savings
Rate-and-term vs cash-out refinancing, closing cost break-even horizon payback formulas, and avoiding reset loan term pitfalls.
Value Added Tax (VAT) Mechanics: Forward Calculation, Gross-to-Net Extraction & Compliance
Tax fraction derivations, reverse VAT extraction algebra, global rate tiers, and invoice rounding protocols.
Purchasing Power Degradation: CPI Modeling, The Rule of 72 & Asset Compounding
Mathematical decay of real capital under persistent inflation, asset class resilience, and historical CPI indices.
The Mechanics of 401(k) Wealth Accumulation: Employer Matches, Compounding & IRS Limits
Employer match capture, mid-year compounding iteration, pre-tax vs. Roth arbitrage, and 4% safe withdrawal rate decumulation.
The 50/30/20 Budgeting Rule: Structural Solvency, Needs vs. Wants & Capital Formation
Macro-allocation frameworks, separating non-negotiable needs from discretionary wants, and high-cost urban 60/20/20 modifications.
Annuity Valuation Mechanics: Discount Rates, Ordinary Annuities vs. Annuities Due & Mortality Pooling
Time value of money derivations, geometric finite sums, fixed decumulation drawdown formulas, and insurance mortality pooling.
Demystifying APR: Prepaid Finance Charges, Regulation Z & Numerical IRR Derivations
Truth in Lending disclosures, separating closing fees from finance charges, and Newton-Raphson internal rate of return root finding.
Bond Pricing Dynamics: Yield to Maturity, Convexity & The Term Structure of Interest Rates
Current yield vs. YTM, Macaulay duration, modified duration price sensitivity, and high-order positive convexity corrections.
Cost-Volume-Profit Analysis: Contribution Margins, Operating Leverage & Break-Even Strategy
Separating fixed overhead from variable costs, unit contribution margin ratios, margin of safety buffers, and operating leverage.
Compound Annual Growth Rate: Geometric Means, Volatility Drag & Portfolio Benchmarking
Why arithmetic averages fail in volatile asset classes, mathematical derivations of geometric means, and Rule of 72 doubling times.
The Taxation of Capital Gains: Long-Term Arbitrage, Basis Stepping & Section 121 Exclusions
Statutory holding period classifications, 2024 federal tax brackets, Net Investment Income Tax (NIIT), and primary residence tax shelters.
The Mathematics of Revolving Debt: Minimum Payment Traps, Daily Compounding & Amortization
Average daily balance accrual, CARD Act geometric decay traps, logarithmic amortization solutions, and negative amortization guards.
Algorithmic Debt Elimination: Avalanche vs. Snowball Optimization & Cash-Flow Rollover
Comparing mathematical interest minimization against behavioral momentum wins, cash flow rollover compounding, and liquidity buffers.
Intrinsic Valuation Mechanics: Discounted Cash Flows, WACC & Terminal Horizon Modeling
Free cash flow to firm discounting, Gordon Growth perpetual terminal value, CAPM cost of equity, and Benjamin Graham margins of safety.
The Mechanics of Financial Independence: Safe Withdrawal Rates, Sequence of Returns & Trinity Derivations
Why savings rate dictates retirement velocity, the Trinity Study 4% rule, sequence-of-returns risk mitigation, and early FIRE archetypes.
The Time Value of Money: Future Value Formulations, Compounding Frequencies & Geometric Series
Temporal preference principles, finite geometric annuity compounding, the continuous limit via Euler constant e, and the Fisher inflation effect.
Home Affordability & Mortgage Underwriting: Front-End/Back-End DTI, PITI & Capital Reserves
Fannie Mae conforming 28/36 qualifying ratios, true cost of ownership PITI breakdown, PMI cancellation, and interest rate purchasing power shocks.
Capital Budgeting & Payback Analysis: Simple Payback, Discounted Cash Flows & Liquidity Risk
Evaluating corporate capital velocity and liquidity risk, simple vs. discounted payback periods, and avoiding the post-payback blind spot.
The Economics & Etiquette of Tipping: Gratuity Percentages, Tax Compounding & Bill Splitting
Pre-tax tip hospitality standards, automated service charges, and equitable group restaurant settlement.
ブログ記事 (3)
Understanding Mortgage Amortization & The Front-Loaded Interest Curve
Why your initial mortgage payments consist almost entirely of interest, and how accelerated principal prepayments reduce total borrowing costs.
The Mathematics Behind Compound Interest: How Money Multiplies
The exponential mathematics of compounding returns, the Rule of 72, and the financial impact of starting investments early.
Understanding Progressive Tax Brackets: Why Earning More Never Makes You Take Home Less
Deconstruct the pervasive myth that a pay raise can reduce take-home pay. Master marginal vs. effective tax rates, bracket buckets, and deductions.
すべての金融計算機
住宅ローン計算機
毎月の返済額、総支払利息、元利均等償還表、繰り上げ返済効果を詳細にシミュレーションします。
複利計算機
積立投資による資産運用成果を、複利効果・定期拠出・インフレ調整を含めてシミュレーションします。
ローン返済計算機
各種ローンの分割支払額、総利息額、および繰上返済による利息削減効果を計算します。
投資リターン計算機
資産運用ポートフォリオの期待利回り、配当再投資効果、長期資産推移を試算します。
リタイアメント・年金計算機
老後資金の必要額、FIRE早期リタイア達成時期、安全資産取崩し率（SWR）を算出します。
マイカーローン計算機
下取り査定額、頭金、消費税、諸費用を含めた自動車ローンの月額返済額を算出します。
給与・時給換算計算機
年収・月給・日給・時給を就業時間や年間休日数に基づき相互換算します。
所得税・税率計算機
累進課税ブラケットに基づく実効税率、限界税率、税引後手取り額を算出します。
頭金シミュレーター
住宅購入時の頭金比率（LTV）、必要自己資金の積立計画、借入総額への影響を分析します。
ローン借り換え計算機
借り換え手数料を考慮した損益分岐点（ブレークイーブン月数）と総利息削減額を比較します。
VAT Calculator
Calculate Value-Added Tax (VAT), add tax to net amounts, or reverse-calculate pre-tax net prices.
Inflation Impact Calculator
Calculate how compounding inflation erodes your cash purchasing power and compute the future cost of today goods.
401(k)資産運用計算機
退職時の401(k)残高、雇用主のマッチング拠出、複利成長、および月々の退職後収入を計算します。
50/30/20 予算ルール計算機
手取り収入をニーズ（50％）、ウォンツ（30％）、貯蓄・投資（20％）に自動配分して計算します。
年金資産・払出計算機
定期年金の将来価値積立、または退職時の定期受取額（取り崩し計画）を計算します。
実質年率（APR）計算機
事務手数料やローン保証料を含む真の実質年率（APR / IRR）を厳密に計算します。
債券利回り（YTM）計算機
最終利回り（YTM）、直接利回り、マコーレー・デュレーション、価格変動リスクを計算します。
損益分岐点（Break-Even）計算機
固定費・変動費から損益分岐点販売数量、損益分岐点売上高、貢献利益率を算出します。
年平均成長率（CAGR）計算機
幾何平均による年平均成長率（CAGR）、総成長率、および72の法則による倍増年数を計算します。
キャピタルゲイン税計算機
短期・長期のキャピタルゲイン税、投資所得税、および売却後の税引後純利益を計算します。
クレジットカード返済計算機
リボ払い・定額返済による完済期間、累計利息、および最小返済額のコストを計算します。
複数借入返済（アバランチ vs スノーボール）計算機
金利重視のアバランチ法と心理的達成感重視のスノーボール法を比較し、最速完済日を算出します。
DCF法・株式企業価値計算機
将来フリーキャッシュフロー（FCF）とWACC（加重平均資本コスト）から企業の理論株価を評価します。
FIRE（早期リタイア）達成計算機
年次支出と安全資産取崩率（4%ルール）からFIRE目標資産額とリタイアまでの年数を算出します。
将来価値（FV）計算機
初期元本と定期積立金が指定した複利利率で将来いくらに成長するかを正確に計算します。
住宅購入適正予算計算機
年収、手持ち頭金、毎月の他債務返済額から無理のない住宅購入上限価格（28/36ルール）を算出します。
回収期間（ペイバック・ピリオド）計算機
設備投資や新規プロジェクトの初期投資回収年数（単純回収期間および割引回収期間）を計算します。
チップ計算・割り勘計算機
レストランのチップ率、税抜金額に基づくチップ計算、飲食代金の均等割り勘を計算します。
Authoritative Guides for 金融
Mortgage Math & Amortization: Principal, Escrow & Front-Loaded Interest
Regulation Z monthly fixed amortization equation, PITI escrow breakdown, early interest curves, and PMI dropoff thresholds.
Loan Amortization Mechanics: How Extra Principal Slashes Borrowing Costs
TILA Regulation Z compounding formulas, bi-weekly payment acceleration, extra principal debt reduction, and amortization curves.
Auto Loan Financing: Interest Rates, Loan Terms & True Vehicle Cost
Truth in Lending Act auto amortization equations, sales tax trade-in tax credits, dealer doc fees, and the 20/4/10 affordability rule.
The Mechanics of Compound Interest: Exponential Growth & Time Horizons
Discrete exponential compounding equations, APY conversion formulas, ordinary annuity vs annuity due, and Fisher real inflation discounting.
Investment Returns & CAGR: Measuring Dividends, Growth & Risk
Return on Investment (ROI), Compound Annual Growth Rate (CAGR), DRIP dividend reinvestment, and capital gains taxation drag.
Retirement Horizons & The 4% Rule: Safe Withdrawal Rates Demystified
William Bengen Trinity Study safe withdrawal rates, accumulation compounding, sequence of returns risk, and social security optimization.
Gross vs. Net Pay: Converting Hourly, Biweekly, and Annual Earnings
Fair Labor Standards Act 2,080-hour baseline, overtime time-and-a-half calculation, pre-tax 401(k)/HSA benefits, and FICA withholding.
How Progressive Tax Brackets Work: Marginal Rates vs. Effective Tax
IRS 2024 progressive marginal brackets, standard vs itemized deductions, FICA payroll withholdings, and effective tax rates.
Down Payments and LTV: How Equity Eliminates Private Mortgage Insurance
Fannie Mae / FHA loan-to-value (LTV) risk tiers, Private Mortgage Insurance (PMI) cost elimination at 20% down, and savings timeline modeling.
Mortgage Refinancing Break-Even: Balancing Closing Costs Against Monthly Savings
Rate-and-term vs cash-out refinancing, closing cost break-even horizon payback formulas, and avoiding reset loan term pitfalls.
Value Added Tax (VAT) Mechanics: Forward Calculation, Gross-to-Net Extraction & Compliance
Tax fraction derivations, reverse VAT extraction algebra, global rate tiers, and invoice rounding protocols.
Purchasing Power Degradation: CPI Modeling, The Rule of 72 & Asset Compounding
Mathematical decay of real capital under persistent inflation, asset class resilience, and historical CPI indices.
The Mechanics of 401(k) Wealth Accumulation: Employer Matches, Compounding & IRS Limits
Employer match capture, mid-year compounding iteration, pre-tax vs. Roth arbitrage, and 4% safe withdrawal rate decumulation.
The 50/30/20 Budgeting Rule: Structural Solvency, Needs vs. Wants & Capital Formation
Macro-allocation frameworks, separating non-negotiable needs from discretionary wants, and high-cost urban 60/20/20 modifications.
Annuity Valuation Mechanics: Discount Rates, Ordinary Annuities vs. Annuities Due & Mortality Pooling
Time value of money derivations, geometric finite sums, fixed decumulation drawdown formulas, and insurance mortality pooling.
Demystifying APR: Prepaid Finance Charges, Regulation Z & Numerical IRR Derivations
Truth in Lending disclosures, separating closing fees from finance charges, and Newton-Raphson internal rate of return root finding.
Bond Pricing Dynamics: Yield to Maturity, Convexity & The Term Structure of Interest Rates
Current yield vs. YTM, Macaulay duration, modified duration price sensitivity, and high-order positive convexity corrections.
Cost-Volume-Profit Analysis: Contribution Margins, Operating Leverage & Break-Even Strategy
Separating fixed overhead from variable costs, unit contribution margin ratios, margin of safety buffers, and operating leverage.
Compound Annual Growth Rate: Geometric Means, Volatility Drag & Portfolio Benchmarking
Why arithmetic averages fail in volatile asset classes, mathematical derivations of geometric means, and Rule of 72 doubling times.
The Taxation of Capital Gains: Long-Term Arbitrage, Basis Stepping & Section 121 Exclusions
Statutory holding period classifications, 2024 federal tax brackets, Net Investment Income Tax (NIIT), and primary residence tax shelters.
The Mathematics of Revolving Debt: Minimum Payment Traps, Daily Compounding & Amortization
Average daily balance accrual, CARD Act geometric decay traps, logarithmic amortization solutions, and negative amortization guards.
Algorithmic Debt Elimination: Avalanche vs. Snowball Optimization & Cash-Flow Rollover
Comparing mathematical interest minimization against behavioral momentum wins, cash flow rollover compounding, and liquidity buffers.
Intrinsic Valuation Mechanics: Discounted Cash Flows, WACC & Terminal Horizon Modeling
Free cash flow to firm discounting, Gordon Growth perpetual terminal value, CAPM cost of equity, and Benjamin Graham margins of safety.
The Mechanics of Financial Independence: Safe Withdrawal Rates, Sequence of Returns & Trinity Derivations
Why savings rate dictates retirement velocity, the Trinity Study 4% rule, sequence-of-returns risk mitigation, and early FIRE archetypes.
The Time Value of Money: Future Value Formulations, Compounding Frequencies & Geometric Series
Temporal preference principles, finite geometric annuity compounding, the continuous limit via Euler constant e, and the Fisher inflation effect.
Home Affordability & Mortgage Underwriting: Front-End/Back-End DTI, PITI & Capital Reserves
Fannie Mae conforming 28/36 qualifying ratios, true cost of ownership PITI breakdown, PMI cancellation, and interest rate purchasing power shocks.
Capital Budgeting & Payback Analysis: Simple Payback, Discounted Cash Flows & Liquidity Risk
Evaluating corporate capital velocity and liquidity risk, simple vs. discounted payback periods, and avoiding the post-payback blind spot.
The Economics & Etiquette of Tipping: Gratuity Percentages, Tax Compounding & Bill Splitting
Pre-tax tip hospitality standards, automated service charges, and equitable group restaurant settlement.
Editorial Articles for 金融
Understanding Mortgage Amortization & The Front-Loaded Interest Curve
Why your initial mortgage payments consist almost entirely of interest, and how accelerated principal prepayments reduce total borrowing costs.
The Mathematics Behind Compound Interest: How Money Multiplies
The exponential mathematics of compounding returns, the Rule of 72, and the financial impact of starting investments early.
Understanding Progressive Tax Brackets: Why Earning More Never Makes You Take Home Less
Deconstruct the pervasive myth that a pay raise can reduce take-home pay. Master marginal vs. effective tax rates, bracket buckets, and deductions.