Free online calculators that show their working
Free calculators for loans, tax, health, maths, construction, shipping, solar, EVs, LLM APIs and cloud costs. Formula and worked example on every page.
437 free calculators across 16 categories.
Popular
- EMI CalculatorFinance
- SIP CalculatorFinance
- Stock Option & RSU Tax CalculatorFinance
- Solar ROI Calculator IndiaEnergy, Solar & EV
- EV vs Gas Total Cost of Ownership CalculatorEnergy, Solar & EV
- California ADU Cost & ROI CalculatorConstruction & DIY
- India Import Duty CalculatorFreight & Logistics
- Digital Nomad Visa Eligibility CheckerTravel & Visas
- Freelance Hourly Rate to Salary CalculatorFinance
- Micro-SaaS Valuation CalculatorFinance
- SaaS Unit Economics CalculatorFinance
- Stamp Duty & Capital Gains Planner (India)Finance
- LLM API Cost CalculatorAI, Cloud & Developer
- Cloud Egress Cost CalculatorAI, Cloud & Developer
- Software Development Cost EstimatorAI, Cloud & Developer
- GLP-1 Dosage CalculatorHealth & Fitness
- VA Disability CalculatorLegal & Payroll
- BMI CalculatorHealth & Fitness
- Percentage CalculatorMaths
- Age CalculatorConverters
- Income Tax Calculator (India)Finance
- Mortgage CalculatorFinance
- Compound Interest CalculatorFinance
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All calculators A–ZFinance
Work out EMIs, plan a SIP and see exactly how much interest a loan will cost you before you sign.
- EMI CalculatorWork out the monthly instalment on a home, car or personal loan — and what it costs you in interest.
- SIP CalculatorSee what a monthly mutual fund investment could grow into, or how much you need to invest each month to reach a goal.
- SWP CalculatorSee how long your savings last when you take a monthly income from them, raised every year to keep up with inflation.
- Stock Option & RSU Tax CalculatorRSU vests, ISO and NSO exercises in one tax year: regular tax, AMT, FICA, what your employer withholds and what is left to pay.
- ISO AMT CalculatorHow many incentive stock options you can exercise and hold before the alternative minimum tax kicks in, and what it costs past that point.
- RSU Tax CalculatorTax on your RSU vest, how many shares sell-to-cover takes, and how much more you will owe in April than the 22% your employer withheld.
Health & Fitness
Track BMI and find the calorie target that matches your body and how active you actually are.
- GLP-1 Dosage CalculatorTurn a prescribed semaglutide or tirzepatide dose in mg into the exact line on a U-100 insulin syringe, with the syringe drawn to scale.
- Semaglutide Dosage CalculatorCompounded semaglutide in mg to units on an insulin syringe, for any vial strength, with the Wegovy titration converted for your vial.
- Tirzepatide Dosage CalculatorCompounded or vial tirzepatide in mg to units on an insulin syringe, with the Zepbound 2.5 to 15 mg titration converted for your vial.
- Peptide Reconstitution CalculatorMix a peptide vial with bacteriostatic water and find the units to draw for a dose in mcg or mg on a U-100 insulin syringe.
- Insulin Syringe Units to mg CalculatorWork backwards from the line on a U-100 insulin syringe to the dose in mg or mcg, for any vial strength.
- Bacteriostatic Water CalculatorHow much bacteriostatic water to add to a vial so each dose lands on an easy line, like 10 or 20 units, on a U-100 syringe.
Maths
Everyday arithmetic without the mental gymnastics, with the working shown step by step.
- Percentage CalculatorWork out a percentage of a number, what share one number is of another, or the change between two values.
- Fraction CalculatorAdd, subtract, multiply and divide fractions, with the answer reduced to lowest terms and shown as a decimal.
- Scientific CalculatorTrigonometry, logs, powers, roots and factorials in degrees or radians. Type the whole expression or use the keypad.
- Average CalculatorMean, median, mode, range and standard deviation of any list of numbers. Paste a column straight from a spreadsheet.
- Ratio CalculatorSimplify a ratio to lowest terms, or find the missing number in a proportion such as 16 : 9 = 1280 : ?
- Square Root CalculatorSquare, cube and higher roots, with the simplest radical form such as √72 = 6√2.
Everyday
Quick sums for daily life: splitting a bill, checking a sale price and what a trip will cost in fuel.
- Tip CalculatorWork out the tip and split the bill, with an option to round each share up to a whole dollar.
- Discount CalculatorThe sale price and how much you save, including an extra coupon on top and any tax added at the till.
- Fuel Cost CalculatorWhat a trip will cost in petrol or diesel, one way or return, split between passengers. Kilometres or miles.
Converters
Convert units and currencies, and work out exact ages, date differences and time durations.
- Unit ConverterConvert length, weight and temperature between metric and imperial units.
- Age CalculatorWork out an exact age in years, months and days — and how long until the next birthday.
- Date Difference CalculatorDays between two dates, in years, months and days, weeks, and weekdays, with or without the end date.
- Time Duration CalculatorHours and minutes between two times, overnight shifts included, less a break, in decimal hours for timesheets.
- Currency ConverterConvert between 30 currencies at the European Central Bank's reference rates, with the rate and its inverse.
Weather
Turn a forecast into the answer you actually want — starting with whether school is likely to be called off tomorrow.
Hobbies & Crafts
The small, awkward sums that come up mid-project — paper, tuning, kerf widths and tank chemistry.
- Scrapbook Paper CalculatorHow many sheets a project needs, and which way round to cut them for the least waste.
- Piano Tuning Interval CalculatorFrequency for any note from any reference pitch, in equal temperament or just intonation.
- Waterjet Kerf CalculatorEntry and exit kerf, taper and the tool offset to program, for any material and thickness.
- Shrimp Tank Water CalculatorTarget GH, KH, TDS and pH for your species, and what a water change will actually do to them.
- Yarn Yardage CalculatorHow many skeins a hat, sweater or blanket takes in any yarn weight, knitted or crocheted.
Pets
Feeding portions and husbandry maths by species, from everyday dogs and cats to the exotic pets generic calculators ignore.
- Parrot Feeding CalculatorDaily food by weight for your species — split into pellets, fresh food and the treat ceiling.
- Reptile UVB Distance CalculatorHow far the lamp should sit from the basking spot to hit your species' Ferguson zone.
- Fish Medication Dosing CalculatorDose by actual water volume for common aquarium treatments, at full or reduced strength.
- Dog & Cat Food CalculatorHow much to feed by species, weight and life stage, in cups and grams of your actual food.
Construction & DIY
Price a California ADU with each city's real permit and impact fees, and order the right amount of concrete, gravel, paint, tile, drywall, fencing and sod the first time, with the waste allowances contractors actually use.
- California ADU Cost & ROI CalculatorWhat an ADU or garage conversion costs to build in 20 California cities, with each city's permit, impact and school fees and the state exemptions applied, and how long the rent takes to pay it back.
- Los Angeles ADU Cost & Permit Fee CalculatorA 600 sq ft ADU in Los Angeles runs about $315,000 all in, $16,728 of it city and school fees. Price your own build, fees and rental payback.
- San Diego ADU Cost & Permit Fee CalculatorA 600 sq ft ADU in San Diego runs about $309,000 all in, $23,450 of it city and school fees. Price your own build, fees and rental payback.
- San José ADU Cost & Permit Fee CalculatorA 600 sq ft ADU in San José runs about $334,000 all in, $9,519 of it city and school fees. Price your own build, fees and rental payback.
- San Francisco ADU Cost & Permit Fee CalculatorA 600 sq ft ADU in San Francisco runs about $364,000 all in, $14,228 of it city and school fees. Price your own build, fees and rental payback.
- Fresno ADU Cost & Permit Fee CalculatorA 600 sq ft ADU in Fresno runs about $227,000 all in, $6,974 of it city and school fees. Price your own build, fees and rental payback.
Freight & Logistics
India import duty and landed cost by HS code, plus density, cube and billable weight worked out before the carrier does it for you, so a quote does not turn into a reclass invoice.
- India Import Duty CalculatorFind your product's HS code, then see Basic Customs Duty, SWS, IGST and the landed cost of importing it into India, with FTA rates where they apply.
- Smartphone Import Duty Calculator IndiaCustoms duty, SWS and IGST on smartphones imported into India, and what a Vietnamese or Korean certificate of origin saves over China.
- Laptop Import Duty Calculator IndiaImport duty on laptops and tablets brought into India: no Basic Customs Duty, 18% IGST, and the import authorisation to get first.
- Smartwatch Import Duty Calculator IndiaCustoms duty on smartwatches and fitness bands imported into India, with the 20% BCD, SWS and IGST, and the rate from ASEAN.
- Earbuds and Headphones Import Duty Calculator IndiaCustoms duty on TWS earbuds, headphones and headsets imported into India, with the 20% BCD, SWS, IGST and landed cost.
- LED TV Import Duty Calculator IndiaCustoms duty on LED and smart TVs imported into India, with 20% BCD, SWS and 18% IGST after GST 2.0.
Sports
Pitching stats, golf handicap differentials and fantasy football scoring, worked out the way the official rules do it.
- ERA CalculatorEarned run average and WHIP, reading innings the way a box score writes them.
- Fantasy Football Points CalculatorScore any stat line in PPR, half PPR and standard leagues, side by side.
- Golf Handicap CalculatorScore differential, course handicap and net score under the World Handicap System.
Education
Know exactly what you need on the final before you walk into the exam room.
Legal & Payroll
Rough, transparent estimates for VA disability ratings, paychecks and injury claims — the starting point for a conversation with a VSO, payroll provider or lawyer, never a replacement for one.
- VA Disability CalculatorCombine your VA ratings step by step as a rater does, with the bilateral factor, its 2023 exception and your 2026 monthly pay.
- VA Bilateral Factor CalculatorApply the 10% bilateral factor to disabilities of both arms or both legs, and see whether the 2023 exception raises your rating.
- VA Combined Ratings TableThe full 38 CFR 4.25 Table I, generated and checked against the regulation, with a calculator that reads it for you.
- VA Disability Pay Chart 2026Monthly VA compensation for every rating and family size, effective December 1, 2025, with a calculator for your exact dependents.
- California Paycheck CalculatorTake-home pay after federal tax, California tax, SDI, Social Security and Medicare, using 2026 tables.
- Personal Injury Settlement CalculatorA rough claim value by the multiplier method, after your share of fault, legal fees and costs.
Energy, Solar & EV
Work out what rooftop solar would save on your DISCOM's tariff, and whether an electric car is cheaper to own than a gas one on your state's electricity prices and utility EV plan.
- Solar ROI Calculator IndiaEnter your electricity bill and state to see the rooftop system you need, your PM Surya Ghar subsidy, payback period and 25-year return.
- Pune Solar Calculator (MSEDCL)Rooftop solar payback for Pune and the rest of MSEDCL's Maharashtra, on the FY 2026-27 MERC slabs, wheeling charge and 16% duty.
- Bangalore Solar Calculator (BESCOM)Rooftop solar payback for Bangalore homes on BESCOM's flat KERC tariff, fixed charge per kW and this year's true-up charge.
- Delhi Solar Calculator (TPDDL)Rooftop solar payback for North Delhi homes on Tata Power-DDL, with the Delhi top-up, generation incentive and 200-unit subsidy.
- Delhi Solar Calculator (BSES Rajdhani)Rooftop solar payback for South and West Delhi homes on BSES Rajdhani, with the Delhi top-up, generation incentive and BRPL's PPAC.
- Uttar Pradesh Solar Calculator (UPPCL)Rooftop solar payback for Lucknow, Noida and the rest of Uttar Pradesh, with the UPNEDA top-up of ₹15,000 a kW on UPPCL's slabs.
AI, Cloud & Developer
Price software before you commit: what an agency will charge to build your app, LLM API spend across Claude, GPT and Gemini, and cloud data transfer bills across AWS, Google Cloud, Azure, Cloudflare and budget clouds.
- LLM API Cost CalculatorPrice a real workload across Claude, GPT, Gemini, DeepSeek, Grok and Qwen side by side, with prompt caching, batch discounts and exact token counts.
- Prompt Caching ROI CalculatorSee whether caching your system prompt or documents pays off: cache writes, reads, expiry and break-even for Claude, GPT and Gemini.
- LLM Cost per Million Words CalculatorWhat it costs to have Claude, GPT or Gemini read or write a million words, with words converted to tokens for you.
- AI Chatbot Cost CalculatorWhat a customer support or assistant chatbot costs to run on Claude, GPT or Gemini per month, with the system prompt cached.
- RAG Cost CalculatorWhat retrieval-augmented question answering costs per question and per month, when every answer is built from retrieved passages.
- AI Coding Agent Cost CalculatorWhat an AI coding agent costs per task and per month, where every step resends a large context that mostly caches and the model thinks before it acts.
Travel & Visas
Check your income against the financial requirements of digital nomad and remote work visas, with thresholds pegged to each country's minimum wage worked out for this year and converted at today's exchange rate.
- Digital Nomad Visa Eligibility CheckerEnter your income once to see which of 17 digital nomad visas you qualify for, with 2026 minimum-wage thresholds and today's exchange rates.
- Spain Digital Nomad Visa Income CalculatorCheck your income against Spain's digital nomad visa: 200% of the 2026 SMI, plus 75% for the first family member and 25% for each after.
- Portugal D8 Visa Income CalculatorCheck your income against Portugal's D8 digital nomad visa: four times the 2026 minimum wage, with add-ons for a partner and children.
- Italy Digital Nomad Visa Income CalculatorCheck your income against Italy's digital nomad visa: three times the healthcare exemption floor, about €24,790 a year before family.
- Greece Digital Nomad Visa Income CalculatorCheck your net income against Greece's €3,500 digital nomad threshold, with 20% more for a spouse and 15% for each child.
- Croatia Digital Nomad Visa Income CalculatorCheck your income against Croatia's digital nomad permit: 2.5 times last year's average net salary, or a year's worth in savings.