Are the calculations safe for my privacy?

Yes, all the math runs locally inside your browser on your phone or computer, so your values never leave your device and we do not track, store or sell any of your numbers, which is the reason we built the calculators to work offline from the start.

Why can't I just subtract 20% to remove VAT?

Because VAT was added on top of a smaller number, the net price, and if you simply subtract 20 percent from the gross you are taking the percentage from the wrong base, so to pull it out correctly you divide the gross by 1 plus the rate as a decimal, for example gross divided by 1.20 for 20 percent, which gives you the net and then the exact VAT by subtraction.

What is the main difference between margin and markup?

The base they use changes the story completely, because margin measures profit against the selling price and shows how much of each euro you collect is really profit, while markup measures profit against the cost and shows how much you added on top of what you paid to get to that price.

How does the offline mode work?

On your first visit your browser caches the lightweight HTML and JavaScript that run CalcTracker, which are small on purpose, and after that the core calculator pages open instantly even without internet access because they no longer need to fetch anything from the network.

Are the results good enough for tax filings?

Our calculators use standard, well tested formulas that match official sources, but since local rules vary and the inputs are yours, we recommend having the final figures checked by a certified professional before you file any official declaration, just to be safe.

CalcTracker Free Online Calculators

Precision calculation helper tools designed for performance, speed, and privacy.

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53free online calculatorsOfflineworks without internet€0no signup, no paywall

All Calculators(53)

Finance & Tax

Discount Calculator→

Enter the original price and discount to see what you save and what you pay, with the math laid out in plain steps so you can check a sale in seconds without guessing at the till.

Final Price = Original Price - (Original Price * (Discount % / 100))

Reverse Discount Calculator→

Work backwards from the sale price to find the original price before the markdown, with the saving shown so you can verify tags and file expenses.

Original Price = Sale Price / (1 - (Discount % / 100))

Price Change Calculator→

Compare an old price and a new price to see the absolute change and the percent change, so you can spot inflation or a real bargain.

Change % = ((New Price - Old Price) / Old Price) × 100 | Absolute = New - Old

Currency Converter→

Convert amounts between Euro (EUR), US Dollar (USD), British Pound (GBP), Japanese Yen (JPY), Swiss Franc (CHF), Canadian Dollar (CAD), and Australian Dollar (AUD) instantly.

Converted = Amount * Rate | Fee Adjustments integrated

Split the Bill→

Easily distribute restaurant checks, shared flats, and trip splits with tips included.

Per Person = [ Total + (Total * Tip % / 100) ] / Guest count

Tip Calculator→

Work out restaurant tips and split the bill fairly among friends, so you can settle the table without passing the phone around or guessing who owes what.

Tip = Bill × (Tip % / 100)

Net Salary Calculator→

Calculate your estimated net monthly paycheck from annual gross salary (RAL) and tax modifiers.

Net Salary = (Gross Salary - Social Contributions) - Progressive Tax - Surcharges

Car Ownership Transfer & bollo tax→

Calculate the exact Italian ownership transfer tax (IPT) and annual bollo road tax for any car or motorcycle.

IPT = €150.81 (up to 53 kW) or ≈€3.51/kW (above 53 kW), × (1 + Surcharge) | Bollo = tariff/kW according to Euro class & Superbollo if >185 kW.

Mortgage Calculator→

Estimate your monthly mortgage payment and see the full amortization schedule.

M = P * [ i(1+i)^n ] / [ (1+i)^n - 1 ]

Percentage Calculator→

Find a percentage of any number, or work out increases and decreases, with the steps shown so you can follow the math instead of trusting a blind total.

Percentage Share = Value * (Percentage / 100)

VAT Calculator→

Add VAT to a net price or pull it out of a gross price, switch the rate as needed and see net, VAT and gross side by side without redoing the math by hand.

VAT = Net Price * (VAT Rate % / 100) | Net = Gross Price / (1 + (VAT Rate % / 100))

Margin / Markup Calculator→

See the difference between margin and markup and price with confidence, because the two look alike on a quick quote but push your list price in very different directions.

Margin % = (Profit / Revenue) * 100 | Markup % = (Profit / Cost) * 100

Sales Tax Calculator→

Add sales tax at checkout or pull it out of a total, switch the combined rate and see net, tax and gross side by side.

Tax = Price × (Rate / 100) | Total = Price + Tax | To remove: Net = Gross / (1 + Rate/100)

Future Value Calculator→

Calculate future worth of investment deposits compounded over periodic intervals.

FV = PV * (1 + r)^n + PMT * [((1 + r)^n - 1) / r]

Compound Interest→

See how reinvested interest grows over time. Enter principal, rate and time to project growth.

A = P(1 + r/n)^(nt)

Loan Interest→

Evaluate standard amortized loans and find the total interest paid over the full term.

Total Spend = Installment * Term - Principal

Pension Estimates→

Project your retirement savings and estimate future pension payouts from today's salary.

Pot = Sum [ Contribution * (1 + grow)^(retire_yr - age_yr) ]

Inflation Calculator→

Measure how cumulative inflation alters the purchasing power of your money over time.

Future Price = Current Amount * (1 + Rate / 100)^Years

IMU/TASI Calculator→

Simulate and calculate your Italian local property taxes (IMU and TASI) instantly.

Tax Base = Rendita Catastale * 1.05 * Coefficient

Fuel Cost Calculator→

Calculate trip fuel costs from distance, consumption, and fuel price.

Cost = (Distance / 100) * Fuel Consumption * Liter Price

Salary Converter→

Convert salary between hourly, weekly, monthly, and annual amounts quickly, with working hours and weeks per year.

Annual = Hourly x Hours/Week x 52

Health & Fitness

Pregnancy Calculator→

Calculate your estimated due date, current week of pregnancy, and gestational age in a few clicks.

Due Date = LMP + 280 Days + (Cycle Length - 28) Days

Pet Gestation due date tracker→

Track your pet's pregnancy. Estimate delivery date and view vital developmental milestones day-by-day.

Expected Birth Date = Breeding Date + 63 days

BMI Calculator→

Work out your body mass index in seconds and see where you sit in the usual weight bands, without turning a single number into a verdict on its own.

BMI = Weight (kg) / Height (m)²

BMR Calculator→

Find the calories your body burns at rest, the baseline for weight loss, gain, and maintenance.

Male: BMR = 10W + 6.25H - 5A + 5 | Female: BMR = 10W + 6.25H - 5A - 161

TDEE Calculator→

Find your daily maintenance calorie requirements based on metabolic benchmarks and active habits.

TDEE = BMR * PAL (Physical Activity Level)

Heart Age Tracker→

Estimate your heart age from blood pressure, cholesterol, and lifestyle habits.

Heart Age = Demographic Benchmark + Lifestyle Modifier

Daily Water Intake→

Calculate your recommended daily water intake based on weight, activity level, and local climate.

Hydration = (Weight kg * 35 ml) + Activity Addition + Climate Addition

GFR Calculator→

Calculate estimated Glomerular Filtration Rate (eGFR) using CKD-EPI, MDRD, Cockcroft-Gault, and Bedside Schwartz formulas.

eGFR = 142 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^-1.2 × 0.9938^Age × [1.012 if female]

Macro Calculator→

Calculate your optimal daily protein, carbohydrate, and fat targets based on your specific fitness goal.

1g Protein = 4 kcal | 1g Carb = 4 kcal | 1g Fat = 9 kcal

Body Fat Calculator→

Estimate your body fat percentage and lean muscle mass using standard US Navy circumference measurements.

Men: %Fat = 86.010 × log10(Waist - Neck) - 70.041 × log10(Height) + 36.76 | Women: %Fat = 163.205 × log10(Waist + Hip - Neck) - 97.684 × log10(Height) - 78.387

Pace & Race Time Calculator→

Calculate running pace, estimate finish times for 5K, 10K, Half Marathon & Marathon, and compute calories burned.

Pace = Total Time ÷ Distance | T2 = T1 × (D2 ÷ D1)^1.06

Math & Numbers

Math Calculator→

Perform advanced arithmetic, algebraic, trigonometric, and memory computations in one interface.

PEMDAS: Parentheses -> Exponents -> Multiplication/Division -> Addition/Subtraction

Random Number Generator→

Generate pseudo-random numbers with customizable ranges, unique/duplicate modes, sorting, and instant lottery presets.

Random Integer = Math.floor(Math.random() × (Max - Min + 1)) + Min

Distance Calculator→

Measure straight-line distances between major Italian cities in kilometers or miles.

d = 2R * arcsin(√(sin²(Δlat/2) + cos(lat1) * cos(lat2) * sin²(Δlon/2)))

Area and Perimeter Calculator→

Easily find surface area and perimeter of rooms, floors, and plots in square meters and feet. Measure in one unit, get both area and edge length without mixing them up.

Area = Length * Width | Perimeter = 2 * (Length + Width)

Volume Calculator→

Determine volumes for cylinders, spheres, cones, rectangular boxes, and pyramids.

Volume = π * radius² * height

Roman Numeral Converter→

Convert any number to roman numerals or roman numerals to numbers instantly, from I to MMMCMXCIX.

Roman = M(1000) + CM(900) + D(500) + CD(400) + C(100) ...

Average Calculator→

Compute the arithmetic mean, sum, and count of a list of numbers in seconds.

Mean = (x1 + x2 + ... + xn) / n

Standard Deviation Calculator→

Compute the standard deviation, variance, and range of a data set with the option of population or sample statistics.

SD = sqrt(sum((xi - mean)^2) / n) (population)

Base Converter→

Convert numbers between any base from 2 to 36, including binary, octal, decimal, and hexadecimal.

Value = sum(digit[i] * base^(n-1-i))

Fraction Calculator→

Add, subtract, multiply, and divide fractions. Get simplified results, exact values, and decimal equivalents.

a/b + c/d = (a*d + b*c) / (b*d)

Date & Time

Age Calculator→

Determine your precise age in years, months, weeks, days, hours, and minutes. See the remaining days to your next birthday.

Delta(Time) = End Date - Birth Date

Date Duration Calculator→

Find exact date difference: total days, weeks, months, hours, and business working days. Choose to include or exclude the end date and handle leap years correctly.

Days Diff = (End Date - Start Date) in days | Inclusive = Exclusive + 1 | Business Days = Total Days - Weekends

Hours Calculator→

Calculate duration between start and end times, add or subtract time blocks, and handle overnight shifts without mental math. Works with 24-hour and AM/PM input and gives decimal hours for payroll.

Duration = End Time - Start Time - Break | Decimal Hours = Hours + Minutes/60

Sleep Cycle Calculator→

Find the best bedtime or wake-up time based on 90-minute sleep cycles.

Optimal Time = Target Time ± (Cycles × 90 min) ± Fall Asleep Latency (14 min)

Flight Duration→

Estimate flight time between major world cities, including takeoff and landing allowance.

Air hours = (Distance / 800 km/h) + 0.5 hours setup

Everyday & Text

Word & Character Counter→

Count words, letters, characters (with/without spaces), lines, and paragraphs. Analyze reading time and keyword densities.

Words = sequence of non-whitespace tokens | Reading Time ≈ Words / 200 per min

Word Unscrambler→

Instantly find all valid words that can be formed from your scrambled letters.

Dictionary Matching Algorithm

International Size Converter→

Convert fashion sizes easily between US, UK, European, Italian, and Japanese systems.

Italian Size = European Size + 4, or US Size mapping tables

Electricity Cost→

See how much your home appliances cost to run. Enter watts, daily use, and your electricity rate.

Cost = (Watts / 1000) * Daily Hours * Unit Rate * Days

Tile Calculator→

Estimate how many tiles you need for a floor or wall, with waste included.

Required Tiles = (Room Area / Unit Tile Area) * (1 + Safety % / 100)

Password Generator→

Create strong random passwords with custom length and character sets, including symbols, numbers, and mixed case.

Random char = charset[floor(random * charset.length)]

Built for speed

All calculations run entirely in your browser. No server roundtrips and no heavy trackers, just a lightweight static layout. Analytics and advertising scripts load only after your explicit consent.

Offline CapabilitiesOur offline-first build means tools stay ready in any coverage.

Privacy by DesignNo tracking or analytics scripts. Your calculations never leave your device; only consent-based advertising cookies may apply.

I am Davide Coronese, an independent developer. I built CalcTracker because I wanted math tools that are fast and free of invasive trackers or heavy cookies. Every formula is validated by an automated test suite and checked against official publications before it ships, and each tool page lists the sources it relies on. All computations run in your browser, so your numbers stay private.

CalcTracker: fast calculators for discounts, VAT and pricing

Welcome to CalcTracker, which started as a simple idea to keep fast calculators for discounts, VAT and pricing in one place without sending you through five different sites, because when you need to check a sale while you are actually at the till, or pull VAT out of a gross price before you send an invoice, or work out whether a 30 percent margin leaves you anything real after costs, you want the answer right away. Today you find 53 tools here, from discount calculator and percent off calculator to VAT calculator and reverse VAT calculator, plus mortgage calculator and amortization calculator, BMI calculator and BMR/TDEE calculators, compound interest and loan interest, tip calculator and sales tax. Everything runs entirely in your browser so your numbers stay on your phone or computer and never reach a server.

Core Advantages of CalcTracker

100% Free & Unlimited: No subscriptions, paywalls, or accounts needed.
Instant & Offline-First: Computes locally in your web browser with zero latency.
Total Data Privacy: Your financial values never leave your client device.
53 Purpose-Built Calculators: Discounts, VAT, margins, health, and math utilities.
Multi-Lingual Support: Native localized interfaces across 10 global languages.

1. Margin vs. markup
Pricing, which many people treat as a detail to fix at the last minute before publishing a list, actually decides whether something is left in the till at the end of the month or whether you have just covered costs, and to read it properly it helps to keep two measures in mind that use the same ingredients, cost and selling price, but tell different stories, because profit margin looks at profit against revenue and tells you how much of each euro collected is really earnings, while markup looks at profit against cost and tells you how much you added on top of what you paid, and confusing the two, which happens more often than you would think when you are in a hurry, pushes prices too low without you noticing, considering that a 50 percent markup is only a 33 percent margin, so checking both numbers before you tag a product, even for a minute, keeps pricing sustainable over time.
2. VAT and sales tax
Filing taxes, whether you do it yourself or hand the papers to an accountant who will ask for everything in order, needs numbers that are exact down to the cent, and for businesses in the UK and Europe adding VAT to invoices and pulling it out of receipts is daily work that cannot wait. Search for VAT calculator UK or reverse VAT calculator is common because people need to add VAT or remove VAT from a gross price and our VAT calculator handles both directions. In the US sales tax is added at checkout instead, which changes how you budget shipments and landed costs even if the product is the same, and since rates shift by country and by product, from 19 percent in Germany to 27 percent in Hungary with reduced rates in between for food or books, the calculator lets you switch the rate and see net and gross side by side without redoing the math by hand every time.
3. Smarter shopping
During sales like Black Friday, when tags promise big percentages and the queue behind you is not moving, checking the math is what protects your budget more than any slogan, and our discount calculators and reverse discount calculators help with that. If you search how to calculate discount or need a percent off calculator and sale price calculator, you get the real saving and the discounted price instantly, and the reverse discount calculator rebuilds the original price starting from the sale price you actually see on the shelf. That lets you spot in seconds whether a discount has been inflated or whether the figure on the receipt makes sense, while the reverse tool, which I end up using more than I expected, also helps when the receipt shows only what you paid and you need the list price to file expenses or to compare with the price you saw online the week before.
4. Offline-first and private by design
CalcTracker runs entirely in your browser, on your phone or computer, which means nothing you type goes to a server or gets stored somewhere else to be reused later, and after your first visit the pages are cached so the calculators keep working even without an internet connection when you are in a warehouse, on a train, or where the signal is weak, while the interface stays lightweight on purpose so Core Web Vitals remain high even on slow connections and older phones, a choice that makes the difference when you just need a quick total without waiting for a heavy page to load.

Common questions

Q1:Are the calculations safe for my privacy?
Yes, all the math runs locally inside your browser on your phone or computer, so your values never leave your device and we do not track, store or sell any of your numbers, which is the reason we built the calculators to work offline from the start.
Q2:Why can't I just subtract 20% to remove VAT?
Because VAT was added on top of a smaller number, the net price, and if you simply subtract 20 percent from the gross you are taking the percentage from the wrong base, so to pull it out correctly you divide the gross by 1 plus the rate as a decimal, for example gross divided by 1.20 for 20 percent, which gives you the net and then the exact VAT by subtraction.
Q3:What is the main difference between margin and markup?
The base they use changes the story completely, because margin measures profit against the selling price and shows how much of each euro you collect is really profit, while markup measures profit against the cost and shows how much you added on top of what you paid to get to that price.
Q4:How does the offline mode work?
On your first visit your browser caches the lightweight HTML and JavaScript that run CalcTracker, which are small on purpose, and after that the core calculator pages open instantly even without internet access because they no longer need to fetch anything from the network.
Q5:Are the results good enough for tax filings?
Our calculators use standard, well tested formulas that match official sources, but since local rules vary and the inputs are yours, we recommend having the final figures checked by a certified professional before you file any official declaration, just to be safe.