Compute the future value of a single lump-sum investment at compound interest. Universal — no country specifics. Example queries: 'What will ₹1L grow to in 10 years at 7%?', 'future value of $5000 invested at 8% annually for 20 years compounded monthly'.

Compute the future value of periodic contributions (SIP in India, DCA globally). Supports annual step-up of monthly contributions. Example queries: 'SIP ₹5000/month for 15 years at 12%', 'how much SIP to reach 1 crore in 10 years', 'DCA $500/month into index fund for 30 years', 'step-up SIP with 10% annual increase'.

Calculate monthly EMI / mortgage payment for a fixed-rate loan. Returns total interest, total payment, and optional full amortization schedule. Works for home loans, car loans, personal loans, mortgage. Example queries: 'EMI for ₹30L home loan at 8.5% for 20 years', '$300k mortgage at 6.5% for 30 years', 'what if I pay $200 extra per month on my car loan'.

Retirement planning in three modes: (1) corpus_needed — how much lump-sum do I need at retirement? (2) monthly_contribution_for — how much SIP to hit a target corpus? (3) safe_withdrawal — how much can I safely withdraw (4% rule)? Example queries: 'how much corpus to retire with ₹50k/month for 30 years', 'SIP needed to build 2 crore corpus in 20 years', 'safe monthly withdrawal from $1M at 4% rule'.

Health metrics in three modes: (1) bmi — Body Mass Index and WHO category; (2) bmr — Basal Metabolic Rate (Mifflin-St Jeor); (3) tdee — Total Daily Energy Expenditure from BMR and activity level. Example queries: 'BMI for 70kg 175cm', 'BMR for 30-year-old male 80kg 180cm', 'TDEE for moderately active person with BMR 1700'.

Convert an amount between any two currencies using a caller-supplied USD-based rate dict. The caller must provide current exchange rates (USD=1.0 base). Example: convert 1000 USD to INR with rates={'USD':1.0, 'INR':83.5}.

Format a numeric amount as a human-readable currency string. For INR, optionally use Indian lakh/crore notation (₹15.00 L, ₹2.50 Cr). Example queries: 'format 83500 in INR', 'display 25000000 as crores'.

Compute Zakat al-Mal (annual 2.5% Islamic wealth obligation). Sums all zakatable assets, deducts debts, checks nisab threshold (gold or silver basis), and returns the zakat due. Cross-cutting — any Muslim, any country. Example queries: 'how much Zakat do I owe on $25000 savings and $5000 stocks', 'zakat calculation with gold and silver holdings'.

Calculate Islamic financing arrangements — Sharia-compliant alternatives to conventional loans. Three instruments: (1) murabaha — cost-plus sale (Sharia mortgage/asset purchase); (2) ijarah — lease-to-own (Sharia auto-loan/equipment); (3) mudarabah — profit-sharing investment (Sharia FD alternative). Example queries: 'murabaha financing for $100k house at 30% markup over 5 years', 'ijarah lease for car worth $30k at $600/month for 5 years', 'mudarabah: investor puts $100k, profit $20k split 70/30'.

Calculate the monthly savings needed to fund a Hajj pilgrimage by a target year. Accounts for existing savings and halal investment returns (sukuk/equity). Example queries: 'how much to save monthly for Hajj costing $8000 in 5 years', 'hajj savings plan with ₹50000 already saved, 6% return, 3 years'.

Screen a stock for Sharia compliance using AAOIFI standard financial ratios. Checks: business sector (haram/halal), debt ratio, cash ratio, receivables ratio, haram revenue ratio. Returns compliance verdict, failed checks, and purification ratio. Example queries: 'is this tech stock halal?', 'AAOIFI screen for Apple with these financials'.

Calculate income tax for US, UK, Canada, Australia, or India (2026 / FY 2025-26). country='us': federal tax with brackets by filing_status. country='uk': income tax + National Insurance (2025/26). country='ca': federal tax with Basic Personal Amount credit. country='au': income tax + Medicare Levy + optional HECS-HELP. country='in': India new/old regime with 87A rebate + cess. Example queries: 'US tax on $85000 income married filing jointly', 'UK income tax on £50000 salary', 'India income tax ₹12L new regime'.

Analyse US retirement account contributions for 2026. account_type='traditional_401k': employee deferral, employer match, §415 cap, tax savings. account_type='roth_ira': eligibility check and MAGI phase-out calculation. Example queries: 'how much do I save in taxes with 401k contribution', 'am I eligible for Roth IRA at $155k income'.

Calculate End of Service Gratuity (EOSG) for UAE or Saudi Arabia. UAE: Federal Decree-Law 33/2021 — 21 days/year for first 5 years, 30 days/year after. Saudi: Saudi Labour Law Articles 84-87 — ½ month/year first 5 years, 1 month/year after; resignation factor applies. Example queries: 'UAE gratuity for 7 years service at AED 8000 basic salary', 'Saudi EOSG if I resign after 6 years on SAR 5000 salary'.

Calculate VAT for UAE (5%) or Saudi Arabia (15%). Works for both ex-VAT and VAT-inclusive amounts. Example queries: 'UAE VAT on AED 1000 product', 'what is the VAT-exclusive price of SAR 1150 including 15% VAT'.

Estimate ZATCA-collected Zakat for Saudi / GCC nationals (simplified 2.5% estimator). Caller supplies the pre-computed zakat base. Returns zakat due with a disclaimer that actual ZATCA computation requires full financial statements. Example query: 'estimate Saudi corporate zakat on SAR 1M zakat base'.

Calculate an Indian electricity bill using progressive slab tariffs. Use a built-in DISCOM preset ('BESCOM' for Karnataka, 'MSEB' for Maharashtra, 'BSES' for Delhi) or supply custom slabs. The constants BESCOM_RESIDENTIAL, MSEB_RESIDENTIAL, BSES_RESIDENTIAL are importable from calcnook.countries.india.electricity_bill for custom use. Example queries: 'electricity bill for 250 units in Bangalore (BESCOM)', 'Delhi BSES bill for 400 units with ₹100 fixed charge'.