Finance tools
21 tools
Tools for money and taxes: calculators and more.
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Japanese capital-gains tax (20.315%) — stock-sale net calculator
Estimate the 20.315% Japanese tax on listed-stock and mutual-fund capital gains (income tax 15% + 0.315% reconstruction surtax + 5% resident tax). Enter sale proceeds, acquisition cost (incl. buy-side fees) and sell-side expenses; the tool returns the gain, each tax line and the after-tax take-home. Losses display zero tax and a note about the 3-year carry-over deduction. Excludes NISA / iDeCo tax-free balances. Runs entirely in your browser — your figures never leave the device.
financetaxcalculator
Compound interest calculator — lump-sum & monthly contribution
Project the future value of an investment compounded over time. Supports three modes: principal only, monthly contributions, or annual contributions. Great for simulating Tsumitate NISA / iDeCo / certificates of deposit. Year-by-year balances can be exported as CSV. Principal, rate, and term stay in your browser — nothing is uploaded.
financecalculator
Japanese consumption tax calculator — net ⇄ gross at 10% / 8% rate
Convert Japanese consumption tax both ways (net→gross or gross→net) at 10% standard, 8% reduced, or a custom rate. Shows net, tax, and gross amounts together with selectable rounding (floor / round / ceiling). Runs entirely in your browser — no amounts are uploaded.
financetaxcalculator
Credit-card revolving simulator — months to payoff, total interest
Simulate Japanese credit-card revolving (リボ払い) repayments month-by-month from the current balance, fixed monthly payment, and APR. Visualize months-to-payoff, total interest paid, and the principal vs interest split over time. Supports three Japanese-style methods: balance-slide (残高スライド), equal-payment (元利定額), and equal-principal (元金定額). Most card issuers charge 15.0–18.0% APR — keeping the minimum payment low usually grows the balance instead of paying it down, so the tool also lets you compare an extra-payment scenario. Nothing leaves your browser.
financecalculator
Discount Calculator — list price / discount rate / sale price all ways
Compute sale prices, discount amounts, and discount rates in four modes: (1) list price + discount% → savings + final price, (2) list price + sale price → effective discount %, (3) list price + discount amount → discount %, (4) list price + discount1 + discount2 → final price after stacking (e.g. 30% off + extra 10% = 1 − 0.7 × 0.9 = 37% off). Each mode also displays tax-included / tax-excluded values (10% / 8% / custom). Useful for shoppers comparing deals and store owners pricing inventory. Runs entirely in your browser.
financecalculator
Expense splitter — even or organizer-pays-extra
Calculate how much each person owes when splitting a bill. Enter the total and the number of people, choose a rounding unit (1 / 10 / 100 / 500 / 1000), and see the per-person amount instantly. Two modes: (1) 『Even』 — everyone pays the same rounded-up amount, and one person gets a discount on the difference; (2) 『Organizer』 — most pay the rounded-down amount, and the organizer covers the leftover. The reconstructed total and the difference are shown live. Everything runs in your browser.
financecalculator
JP freelance tax estimator — income, resident, health & business tax
Annual tax & social-insurance estimator for Japanese sole proprietors. Covers income tax, resident tax, consumption tax, business tax, and furusato-nozei cap. Runs entirely in your browser.
financetaxcalculator
Furusato-nozei limit calculator — donation cap by salary & family
Estimate the furusato-nozei cap (the donation amount where your own contribution stays at the standard ¥2,000) from annual gross salary, family composition, and social-insurance premium. Shows the income-tax and resident-tax deduction breakdown. Runs entirely in your browser. For sole proprietors, use the freelance-tax-jp tool instead.
financetaxcalculator
Japan gift tax estimator — annual / settlement methods (2024 reform)
Enter the gift amount for the year and estimate the Japanese gift tax under the annual (暦年課税) method. Switch between the special rate (lineal descendants aged 18+) and the general rate (everyone else). The JPY 1.1M annual basic deduction and the NTA rate / quick-deduction tables are applied. The settlement-at-inheritance method (相続時精算課税) is also supported, reflecting the 2024 reform that added a separate JPY 1.1M annual deduction on top of the cumulative JPY 25M lifetime allowance (20% flat above). Runs entirely in your browser — figures never leave the device.
financetaxcalculator
iDeCo / NISA tax-savings calculator — Japan tax-advantaged investing
Estimate the tax savings of Japan's two main tax-advantaged investment accounts. iDeCo mode tallies the annual income-tax + 10% resident-tax deduction on contributions (using the progressive bracket table) AND the 20.315% capital-gains exemption. NISA mode only applies the 20.315% gain exemption. Compare against the after-tax outcome of doing the same monthly contributions in a regular taxable brokerage account. Runs entirely in your browser — your figures never leave the device.
financetaxcalculator
Japan inheritance tax estimator — basic deduction, legal shares, spousal credit
Enter the estate value and your heir composition (spouse yes/no, child / parent / sibling counts) for a Japanese inheritance tax estimate. The tool applies: the JPY 30M + JPY 6M × heirs basic deduction, the per-heir taxable amount from the legal-share split, the NTA quick-deduction tables (8 brackets, up to 55%), the spousal tax credit (zero tax for a spouse taking exactly the legal share), and the 20% surcharge on siblings. Heir-class priority (children → parents → siblings) is detected automatically. Runs entirely in your browser — estate figures never leave the device.
financetaxcalculator
Loan repayment calculator — equal payment & equal principal table
Simulate mortgage, auto, and student-loan repayments under both equal-payment and equal-principal schedules. Enter principal, annual rate, and term to see the monthly payment, total interest, total paid, and a full amortization table. Everything runs in your browser — no loan or income data is uploaded.
financecalculator
Japan mortgage tax credit estimator — 2024–25 caps, 13-year 0.7%
Estimate the Japanese housing-loan tax credit for 2024 / 2025 occupancy. Borrow caps depend on the property class — new build (LTQ / ZEH / energy-code / other) or existing (energy-class / other) — and on whether the household qualifies as 'child-rearing or young couple' for the higher cap. The tool runs an equal-payment amortization, applies the cap to each year-end balance, multiplies by 0.7%, and stretches over 13 years (new) or 10 years (existing). Any unused income-tax credit spills into the resident-tax credit (JPY 97,500 / year max). Runs entirely in your browser — loan details never leave the device.
financetaxcalculator
Floating-rate mortgage simulator — 5-year / 125% rule support
Simulate a 'rate hike at year X to Y%' scenario for a Japanese floating-rate mortgage. Enter the original rate, term, hike timing, and post-hike rate to compare the no-hike baseline against the post-hike scenario — monthly payment, total interest, total paid. The 5-year rule (monthly payment frozen for 5 years after the hike) and the 125% rule (the new monthly is capped at 1.25× the previous monthly at the 5-year review) are optional toggles, with any resulting unpaid interest surfaced separately. Runs entirely in your browser — loan figures never leave the device.
financecalculator
Mortgage prepayment simulator — period-reduction vs payment-reduction
Estimate interest savings from prepaying part of a Japanese mortgage. Plug in the original principal, rate, and term plus the prepayment amount and timing (year), and the tool compares the two prepayment styles: period-reduction (keep monthly payment, shorten the loan) vs payment-reduction (keep the original end date, lower the monthly payment). Equal-payment amortization is assumed. Runs entirely in your browser — loan details never leave the device.
financecalculator
Japan pension estimator — basic + earnings-related (FY2026 figures)
Enter your accumulated months in the National Pension and the Employees' Pension, plus your average standard remuneration during the employees' pension period, to estimate the annual / monthly public pension you'll receive in retirement. Uses the FY2026 (令和 8 年度) full basic-pension figure of JPY 847,300/year (JPY 70,608/month) and the 5.481/1000 earnings-related multiplier (Heisei-15-and-later formula). Pro-rates by contributing months so partial careers (20–60 years of age, 25 / 30 / 35 years of coverage) work too. Runs entirely in your browser — salary figures never leave the device.
financecalculator
Japan property tax estimator — fixed-asset 1.4% + city-planning 0.3%
Estimate Japanese property tax (固定資産税 1.4%) and city-planning tax (都市計画税 0.3%) from your land and building assessed values. Applies the residential-land standard-tax reduction (1/6 for the first 200 ㎡, 1/3 above), and the new-build 1/2 reduction on the building portion (FY2026 reform extended this until March 2031: 3 years for houses / 5 years for condos, 5/7 years for certified long-term-quality homes). Runs entirely in your browser — assessed values never leave the device.
financetaxcalculator
Japanese retirement-allowance tax estimator — 退職所得控除 calculator
Enter your retirement allowance and tenure to estimate the retirement-income deduction (退職所得控除), taxable amount with the 1/2 rule, income tax, special reconstruction tax, resident tax and net take-home. Supports the short-tenure variants (短期退職手当等 / 特定役員退職手当等) and the disability bump. Runs entirely inside your browser — figures never leave your device.
financetaxcalculator
Japan side-income tax estimator — the 200k-yen filing threshold
Plug in your salary, side-job revenue and expenses to estimate the extra income tax, reconstruction surtax and resident tax — plus net take-home — that the side gig adds on top of a salaried job. Detects the JPY 200,000/year filing threshold (no income tax under it, but resident tax filing is still required). Switch between miscellaneous and business income; business + blue-return adds the JPY 650,000 deduction. Runs entirely in your browser — figures never leave the device.
financetaxcalculator
Stock Price % Mover (buy price → target %)
Calculator that answers 'what's the price if my stock goes +30%?' or 'where's my -10% stop-loss line?' at a glance. Enter your buy price and currency (¥ / $), and instantly see target prices for +100% / +50% / +30% / +20% / +10% / 0% / -10% / -20% / -30%. Add a custom % row for your own take-profit or stop-loss target. Great for placing limit orders, planning entry/exit, or charting milestones up to a 10-bagger (+900%). Runs entirely in your browser — your numbers are never uploaded.
financecalculator
About this category
Money-related calculators that run inside your browser: Japanese tax calculators (income tax, resident tax, consumption tax, property tax, gift tax, inheritance tax, retirement-income tax, etc.), loan-payment simulators, compound-interest projections, iDeCo / NISA forecasts, and furusato-nozei limit estimators.
All the figures you enter — amounts, household composition, income details — stay in your browser. Results are not sent anywhere, so the tools work as a safe place to draft scenarios before talking to a tax accountant or financial planner.
What you can do
- Estimate income tax / resident tax from salary, side income, or freelance income
- Simulate mortgage tax deductions, prepayments, and floating rates
- Estimate the furusato-nozei donation limit
- Project future assets from iDeCo / NISA contributions
- Estimate gift, inheritance, retirement, capital-gains, and property tax
- Model long-term compound-interest growth
Category FAQ
- Can the results be used as official tax figures?
- These are rough-estimate tools. For the final tax amount or filing, use a tax accountant, the tax office, or an official filing tool. Special cases and deductions vary by situation; always consult official sources before important decisions.
- Which tax year is supported?
- Each calculator states which year it targets. We try to track recent revisions, but at year boundaries some information may be slightly out of date.
- Is it safe to enter personal details (income, dependents)?
- Yes. Everything you enter stays in your browser and is used only for the calculation. Nothing is sent to a server or a third party.
- Are non-Japanese tax systems supported?
- Currently the focus is Japan. Calculators for other countries will be considered based on demand.