Calculator use cases

Calculate your full monthly mortgage payment — principal, interest, property tax, insurance, and PMI. See if you clear the 28% affordability rule before you apply.

Drop your gross income, existing debts, down payment, property tax + insurance rates, mortgage rate, term, HOA, maintenance reserve, and job-stability score. Calculator returns three max-purchase tiers — Conservative (33 % back-end DTI + 1 % maintenance), Standard (36 % + 0.5 %), Aggressive (43 % + 0 %, the FHA ceiling) — plus the stretch spread that shows how much more ‘affordable’ a DTI-only calc claims by ignoring maintenance reserve. The differentiator vs every other affordability tool: maintenance and risk are baked into the housing cost, which is the entire reason DTI-only calcs lure buyers into stretch purchases that break their budget by year three.

Drop home price, down %, mortgage rate, term, property tax, HOA, maintenance, insurance, expected appreciation, current rent, rent inflation, alt investment return, time horizon, transaction cost %, and marginal tax rate. Calculator runs an NYT-style net-worth-at-horizon comparison: both paths start with the same down-payment cash; renter invests it in the market; whichever path has lower annual housing cost invests the cash-flow surplus at the alt-return rate. Output: net-wealth delta at horizon, break-even year, and sensitivity to ±1 pp shifts in appreciation and rent inflation.

Paste a price, your income, and your monthly expenses. Get a clear YES / NO / BORDERLINE verdict based on how much of your surplus the purchase actually takes.

Pinpoint the exact month your loan reaches 80% LTV (cancellation request) and 78% LTV (automatic termination per HPA), with extra-payment acceleration modeled.

Enter the offer + your current comp. Get three counter tiers (conservative / mid / aggressive) with monthly take-home and 5-year cumulative comp under each — so you walk into the negotiation with a number, not a feeling.

Drop two job offers' salary, signing bonus, equity, annual bonus, retirement match, and benefits — get total annualized comp side-by-side, plus a cost-of-living adjusted comparison so you can compare offers in different cities honestly.

Drop your current salary and the gross raise (dollars or percent) — the calculator tells you what actually hits take-home after marginal federal + state + FICA tax. Per-paycheck and per-month deltas included for budgeting.

Multi-country net-pay calculator. US (2026 federal + FICA + 401k/HSA/state), UK (2025/26 PAYE + NI), India (FY 2025-26 new + old regime + 4% cess). Pick a country, drop a salary, see exactly what lands in your bank.

Your quoted salary is not your real rate. Add your commute and work expenses — this calculator shows the hourly rate your job is actually paying after the hidden costs.

See exactly when a refinance pays for itself, what you save over your remaining stay, and whether the lower monthly hides a longer-term interest trap.

Math the trade-off between dumping extra cash on the mortgage vs sending it to the market — over your real horizon, after capital-gains tax, with the risk asymmetry called out.

Pinpoint the exact month your loan reaches 80% LTV (cancellation request) and 78% LTV (automatic termination per HPA), with extra-payment acceleration modeled.

Project your retirement nest egg using future-value math with monthly compounding. Enter current age, target retirement age, present savings, annual contribution, and expected return — get the future value, the 4% safe-withdrawal income, and your FIRE number.

Drop your current net worth, monthly contribution, years to retirement, retirement length, target annual spend, expected return mean + standard deviation, inflation, Social Security expected, and spend flexibility band. Calculator runs 500 stochastic simulations of accumulation + withdrawal, returns success probability, P10/median/P90 percentile bands, the +$500/mo contribution-lever lift, and a sequence-of-returns stress test. Anchored to Bengen 1994 SAFEMAX research, Trinity Study (Cooley/Hubbard/Walz 1998), and Kitces dynamic-spending updates.

Apples-to-apples Roth vs Traditional comparison that models the tax-deduction savings invested separately, surfaces the breakeven retirement bracket, and stops pretending the answer is obvious.

Apples-to-apples claim-age comparison with proper SSA-actuarial reductions, +8% delayed credits, COLA compounding, and the three pairwise breakeven ages most online calcs leave out.

Project the final balance on a lump sum, a monthly contribution, or both. See the interest-vs-contribution split and find out how long until your money doubles.

Enter all your debts and an extra monthly payment. The calculator simulates month-by-month payoff using snowball (smallest balance first) or avalanche (highest APR first) and compares against the minimum-only baseline.

Drop your balance and APR, then either set a monthly payment to see how long it takes (and what interest you'll pay), or pick a target timeline and the calculator solves for the required monthly payment. Flags the case where your payment can't cover monthly interest.

Calculate your monthly EMI for any personal, auto, or home loan. See total interest, how much an extra payment saves, and if the deal is worth signing.

Math the trade-off between dumping extra cash on the mortgage vs sending it to the market — over your real horizon, after capital-gains tax, with the risk asymmetry called out.

Multi-country tax owed estimator. Drop your gross salary, pick your country (and US filing status / India regime), see total tax + after-tax income with the bracket math broken down line by line.

Pick country + income. The calculator shows your marginal rate (the bracket your NEXT dollar lands in), your effective rate (the blended rate across all dollars), and what a $5k raise actually nets after federal income tax.

Enter your salary + RSU vest + YTD prior vests. The calculator shows the 22% supplemental flat withholding vs your real marginal tax — and the cumulative shortfall across the year that triggers FAANG-tier April balances.

Toggle between ISO and NSO. The calculator runs the IRS 2026 federal brackets + Form 6251 AMT math + FICA — and tells you exactly how much tax you owe at exercise, plus the cash you actually need on hand.

Plug in your projected income, withholding, and last year's numbers. The calculator applies the IRS safe harbor and tells you exactly what to send by April 15 — and the same amount each following quarter.

Enter your salary + bonus + state. The calculator shows the supplemental flat withholding (22% federal) versus your real marginal tax — and tells you whether you'll get money back at filing or owe more.

Mifflin-St Jeor BMR, your Total Daily Energy Expenditure, and a complete macro split (protein · fat · carbs) for your weight-loss, maintenance, or muscle-gain goal.

Drop your weight, height, age, sex, activity level, goal (cut, maintain, bulk) and aggressiveness. Calculator returns Mifflin-St Jeor BMR, TDEE with ACSM 2018 activity factors, target calories with the goal modifier applied, ISSN 2017-anchored protein target (1.0-1.4 g/lb cuts, 0.8-1.0 bulks), fat (28% cuts / 22% bulks of kcal — above the hormonal-floor minimum), carbs filling the remainder, and the expected weekly weight change at that deficit or surplus.

Daily calorie target plus the exact protein / fat / carbs split (in grams) for cutting, maintaining, or bulking — adapted to your diet preference (balanced · high-protein · keto · mediterranean). Goal-aware splits, not a fixed 40/30/30.

The most-validated tape-only body fat estimate. Drop your waist, neck, height, and (women) hip — get body fat percentage with category, accuracy band, and where you sit on the fitness range.

Drop your bodyweight, goal, and meal frequency — get your daily protein target in grams plus per-meal breakdown. Goals span sedentary maintenance (0.8 g/kg) through cutting (2.4 g/kg).

Calculate your body mass index instantly in metric or imperial units. See your WHO category, healthy weight range, BMI Prime, and an AI insight for your result.

Drop your last menstrual period (LMP) or conception date — get the estimated due date, current gestational age in weeks/days, trimester, and the full-term window. Cycle-length adjustment included.

Find your exact gestational age (weeks + days) from LMP, conception date, known due date, or first-trimester ultrasound CRL. Plus a complete week-by-week milestones reference (size, length, common symptoms, key appointments) — non-medical, evidence-aligned.

Predict your most-likely ovulation date and the 6-day fertile window from the first day of your last period (LMP) and your cycle length. Sister calc to Pregnancy Due Date.

Drop EV + ICE prices, annual miles, electricity rate, gas price, gas trajectory, maintenance + insurance deltas, EV tax credit, and 5-yr resale delta. Calculator computes 5-year total cost of ownership for both vehicles, surfaces fuel / maintenance / insurance / resale gaps, and finds the electricity rate at which the comparison flips. Anchored to AAA Driving Cost study, NAIC insurance data, KBB / BLS resale benchmarks, and IRS Section 30D EV tax credit.

Compare an EV against a gas car over your ownership window. The calculator shows annual operating savings, upfront premium recovery time, and net dollar savings — with every assumption editable.

Compare buying vs leasing the same car over your actual stay length. The calculator shows total cost both ways + the break-even year — the ownership length where buying flips from worse to cheaper.

Most drivers underestimate by 50%+ because they only count fuel. This calculator forces fuel + insurance + maintenance + depreciation into the picture, then compares against the IRS $0.67/mi standard.

What your commute actually costs — vehicle (fuel + wear + parking) plus the lost-time cost at your hourly wage. Most calcs only show fuel; this one shows the full bill, then tells you how much remote work would save.

Tuition + lost wages × workMode + post-grad job search vs (post-grad salary uplift × landing-rate probability) × career years remaining. Returns expected ROI (honest about landing-rate risk) AND conditional ROI (if you land). Anchored to CIRR / SwitchUp audited placement data — not bootcamp marketing claims.

Tuition + lost wages (depends on full-time-quit vs part-time vs online) + loan interest vs post-grad salary uplift × your remaining career years. Returns total cost, total uplift, payback period, ROI %, and effective annual return — anchored against the 7% real S&P benchmark so you can see whether the investment beats putting the same dollars in an index fund.

5–6 years on a PhD stipend versus 5–6 years of compounding salary + investments. Plug in your current salary, expected stipend, PhD duration, post-PhD salary, raise rate, expected return, savings rate, and career horizon. Calculator runs full year-by-year wealth simulation for both paths and returns the net wealth gap, the year PhD wealth catches up to the work path (if it ever does), and lifetime earnings on each side. The post-PhD salary uplift compounded across decades is the actual lever — the stipend years are usually the smaller piece.

What does taking 6-12 months off mid-career actually cost? Calculator returns BOTH the cash cost (savings needed) AND the long-term opportunity cost — lost wages + lost retirement compounding + re-entry salary penalty across remaining career. Most online sabbatical calcs show only the cash number; the lifetime cost is usually 5-10× larger.

Drop your monthly bill, local kWh tariff, roof area, panel tier, battery option, financing, net-metering policy, electricity-price appreciation, panel degradation, and time horizon. Calculator sizes the system to your usage (or roof, whichever is smaller), applies the IRS Section 25D 30% federal tax credit, simulates production with degradation and tariff escalation, and returns payback period, 20-yr savings, IRR, battery payback delta, and lifetime CO₂ avoided. Anchored to NREL PVWatts insolation, LBNL field-study degradation curves, and EIA grid-emissions data.

Drop your current heating fuel + annual heating bill, climate zone, home sq ft, insulation rating, electric rate, install cost, and tax credit. Calculator converts your bill into BTUs delivered, applies the climate-zone-appropriate seasonal COP for an air-source heat pump, computes operating cost + annual savings + payback period, and surfaces a fuel-trajectory-accelerated payback row plus an insulation-upgrade opportunity hint when implied heating demand exceeds the norm. Anchored to DOE EnergyStar field studies, AHRI 210/240 testing, EIA fuel + electricity data, and IRS Section 25C / IRA HEEHRA rebate programs.

Drop home sq ft, current insulation R-value, target R-value, climate zone, current heating + cooling bill, install cost, and fuel-price growth. Calculator computes heat-loss reduction (1 − R_current/R_target), bill savings, payback period, 20-year lifetime savings with fuel appreciation, and IRR. Surfaces a tier-progression hint when current target leaves meaningful additional savings on the table. Anchored to DOE Building America + IECC 2021 R-value targets, LBNL field studies of envelope retrofits, and IRS Section 25C 30%-up-to-$1,200/yr credit.

Drop room sq ft, ceiling height, climate zone, sun exposure, occupants, insulation rating, electricity rate, and your considered SEER tier. Calculator computes the right-sized BTU/hr (Manual J Square-foot-method approximation), rounds up to nearest 0.5 ton, and compares install + 10-yr operating cost across SEER 14 / 17 / 22 efficiency tiers — recommending the tier with lowest total cost of ownership and surfacing SEER 22 vs SEER 17 marginal-payback. Anchored to ACCA Manual J 8th Ed sizing standard, DOE 2023 SEER2 ratings, and EIA cooling-degree-day data.

Drop your monthly kWh, peak / off-peak TOU rates, EV charging time, appliance flexibility tier, heating type, willingness to shift hrs/wk, and battery option. Calculator computes manual-shift savings (moving load from peak → off-peak via thermostat scheduling, dishwasher / dryer / hot-water timing, EV charging window) and a separate battery-arbitrage scenario (battery charges off-peak, discharges peak — full TOU spread captured automatically). Recommends whether battery storage pays back at your specific TOU spread + bill size. Anchored to California NEM 3.0 + EV-2A rate schedules, DOE residential battery field studies, and IRS Section 25D 30% residential clean energy credit.

Drop your current city + salary + target city — get the equivalent salary needed in the new city to maintain the same purchasing power. 66 major world cities, Numbeo-style indices.

Drop your origin city, target city, current annual salary, remote-work salary policy (same / adjusted to local market / hub-based capped at 15% reduction), an optional COL override, a tax delta, and your climate + social-cost priorities. Calculator computes the real purchasing-power change for the policy you pick AND the same-pay vs hub-based variants side-by-side, then runs a 3-factor traffic-light read on climate, taxes, and social cost so you know which factor is gating the move. Anchored to Numbeo cost-of-living indices (66 cities), Quality-of-Life proxies (safety + healthcare + amenities + lifestyle), and climate scores (0-100, year-round mildness).

Drop your current salary, current city, proposed remote city, your employer's pay-band policy (national / hub-based / location-based), and how much negotiation leverage you have. The calculator computes the salary your employer's policy will offer, brackets a fair-market range using cost-of-living indices, and gives you an open-ask + settle-for target so you walk into the conversation with both anchor and walk-away point clear.

Pick your current and destination countries from 23 presets. Calculator computes the purchasing-power-adjusted income delta + tax rate change + healthcare cost difference + one-time move cost across your planned stay horizon. Numbeo + Mercer COL anchored, OECD tax-wedge defaults.

Drop your list size, growth rate, open + click + conversion rates, LTV per subscriber, and your loaded weekly content cost + monthly platform fees. Calculator computes monthly newsletter revenue, ROI multiple over total cost, the higher-leverage growth move (open rate vs list size based on your current saturation), and a 12-month projection at your current growth — the honest math creators rarely run before scaling cadence.

Drop your posting cadence, hours per post, audience growth rate, monthly monetization, and your real hourly opportunity cost. Calculator surfaces monthly opportunity cost, profitability ratio (monetization ÷ opp cost), break-even hourly rate, and a recommended cadence change — the math behind whether your newsletter is sustainable, or whether you're burning yourself out for a vanity-revenue number.

Drop hours-per-week and monthly value attributable to each of Twitter, LinkedIn, TikTok plus your personal hourly opportunity cost. Calculator surfaces per-platform ROI per hour with a profitable / unprofitable flag, blended ROI/hr across platforms, and the dollar value of reclaiming time from below-opp-cost platforms.

Drop your niche size, current audience, monetization tier, content quality, posting cadence, and differentiation score. Calculator computes the months to a monetization-tier-specific true-fans target using compounding growth math, surfaces quality + cadence upgrade scenarios, and shows the effective monthly growth rate at your inputs.

Drop your platform, niche, US audience %, average watch time, monthly views, and monetization status. Calculator computes effective RPM (base × niche × geo × watch × monetization), monthly + annual projection, and the niche-vs-geography variance attribution that drives 90%+ of RPM differences.

Drop attendees, average loaded hourly rate, duration, and aggregated prep time. The calculator computes direct cost (loaded comp × time), prep cost, and the context-switching tax (Atlassian: 23 minutes per attendee to recover from interruption), then projects the annual cost if the meeting recurs weekly. Big number for cutting status meetings and switching to async.

Drop your current weekly deep-work hours, the dollar value per hour of your output, your context-switch frequency, your target deep-work hours, and the meetings you'd drop to make room. The calculator computes the added value per week, the hours reclaimed (net of async-replacement overhead), and the annualized financial gain — the case for protecting focus time.

Your quoted salary is not your real rate. Add your commute and work expenses — this calculator shows the hourly rate your job is actually paying after the hidden costs.

Every purchase is a trade — dollars for hours of your life. Most people compute their paid hourly rate and stop there, hiding the unpaid life-overhead (commute, chores, decision fatigue) that adds 30-50% on top. Plug in your take-home pay, paid hours, weeks, life-overhead hours, the item you're considering, and the rate you can hire help at. Calculator returns the item's cost in TRUE life-hours (not the rosy paid-rate version), your time-wealth ratio, and the buy-back-time arbitrage available when outsourcing rate < life-rate. Reframe spending as life-hours, not dollars.

Drop your active projects, daily decisions, open todos, weekly meetings, daily notifications, and 7-day average sleep. Calculator computes a 0-100 cognitive-load score against published thresholds (Miller 7-item working memory, Bargh & Vohs 60-decision ceiling, Atlassian 23-min interruption-recovery, Walker sleep literature), identifies your top drag, and recommends the single highest-leverage reclaim.