3-Way Calculator

Design Philosophy

Mon, 01 Jan 0001 00:00:00 +0000

The 3-Way Calculator is built on four principles. Together they define what the app is — and what it is not.

1. Currency-agnostic

The calculator does not assume any currency. The user can think in USD, EUR, GBP, JPY, SAR, or any other currency they work with.

The Decimal Places setting in Settings lets you choose between 0, 0.0, 0.00, and 0.000 decimal places. Whether you need whole numbers, tenths, cents, or millimes, the calculator adapts. Support for 5 and 8 decimal places (for cryptocurrencies) is planned.

Rate Configuration

Mon, 01 Jan 0001 00:00:00 +0000

The flat rate is the percentage used to calculate Before, After, and Amount. It is the single most important setting in the calculator.

What is a flat rate?

A flat rate means the same percentage is applied to every transaction. Common examples include:

VAT / GST — typically 5% to 27% depending on the country
Sales tax — varies by state, province, or city
Commission — a fixed percentage of a sale
Zakat — 2.5% of qualifying wealth
Tipping — often 10%, 15%, or 20%

The calculator does not use tiered or progressive rates. If your use case needs different rates for different transactions, you change the rate each time.

Themes

Mon, 01 Jan 0001 00:00:00 +0000

The calculator includes five visual themes that change colours, fonts, and visual effects across the interface, while leaving functionality unchanged.

Switching themes

Open the drawer menu (click or tap ☰ in the top-left).
Tap Settings.
Scroll to the Theme card.
Select any theme. Changes apply immediately.

Your selected theme is saved and will be restored when you return.

Midnight Executive (default)

Midnight Executive theme preview

Use Cases

Mon, 01 Jan 0001 00:00:00 +0000

Example 1. Calculate VAT on a product price

Scenario: You are a freelancer in the UK. A client agrees to pay you £500.00 including VAT. You need to know your earnings before VAT and the VAT amount.

Steps:

Tap the After field to make it active.
Set the rate to 20%
Enter 500.
The calculator shows:
- Before: £416.67
- Amount: £83.33

Example 2. Find the price including tax (Before → After)

Scenario: You are pricing a product at $120.00 before tax. You need to know the final shelf price including 8% sales tax.

Getting Started

Mon, 01 Jan 0001 00:00:00 +0000

This guide walks you through your first calculation.

The three fields

The calculator screen shows three values:

Field	Meaning (additive)	Meaning (subtractive)	Example
Before X%	Price before tax	Original amount before deduction	$100.00
After X%	Price including tax	Remaining amount after deduction	$115.00 / $85.00
X% Amount	The tax amount	The deduction amount	$15.00

The X is replaced by the current rate (e.g., “Before 15%”). The relationship depends on the calculation direction:

Nudge Feature

Mon, 01 Jan 0001 00:00:00 +0000

The nudge feature lets you adjust a value by one cent ($0.01) at a time, while ensuring the Amount stays the same.

Why nudge exists

Currency calculations with rounding can produce ambiguous results. For example, at a 15% rate, a gross amount of 115.00 produces an Amount of 15.00. But 114.97 and $115.03 might produce the same Amount of 15.00, because both round to the same Amount.

Settings

Mon, 01 Jan 0001 00:00:00 +0000

The Settings page lets you configure the calculator’s behavior and appearance.

Accessing Settings

Click or tap the menu button (☰) in the top-left corner.
A slide-out drawer opens from the left.
Tap Settings.

To return to the calculator, tap the back arrow (←) in the top-left of the Settings header, or use the back button.

Language

Switch between English and Arabic.

English — Left-to-right layout, English labels
Arabic — Right-to-left layout, Arabic labels

When you switch to Arabic:

Terminology Reference

Mon, 01 Jan 0001 00:00:00 +0000

The terms Before, After, and Amount are deliberately generic labels that adapt to whatever domain you work in.

Tax & Core

3-Way Calculator Term	Means	Tax	Tax Withheld	VAT / GST
Before applying flat-rate	the original amount	Taxable Amount / Pre-Tax Amount	Gross Income	Net Price (Excluding VAT/GST)
After applying flat-rate	the adjusted amount	Total Amount / Post‑Tax Amount	Net Income	Gross Price (Including VAT/GST)
Amount difference per flat-rate	the delta (increase or decrease)	Tax Amount	Withholding Amount	VAT/GST Amount
Flat rate	the percentage applied	Tax Rate	Withholding Rate	VAT/GST Rate
Direction	addition or subtraction	Tax Added	Tax Deducted	VAT/GST Added

Commerce

3-Way Calculator Term	Discount	Commission	Markup / Margin	Payroll
Before applying flat-rate	Original Price / List Price	Base Price / Principal Amount	Cost Price	Gross Salary
After applying flat-rate	Discounted Price / Sale Price	Price with Commission Included	Selling Price	Net Salary
Amount difference per flat-rate	Discount Amount / Savings	Commission Amount	Markup Amount	Deduction Amount
Flat rate	Discount Rate	Commission Rate	Markup Rate	Deduction Rate
Direction	Discount Applied	Commission Added	Markup Added	Deduction Applied

Finance & Insurance

3-Way Calculator Term	Zakat	Interest	Insurance
Before applying flat-rate	Zakatable Wealth	Principal	Base Premium
After applying flat-rate	Remaining Wealth After Zakat	Amount Due / Future Value	Total Premium
Amount difference per flat-rate	Zakat Amount	Interest Amount	Loading Amount
Flat rate	Zakat Rate	Interest Rate	Loading Rate
Direction	Zakat Deducted	Interest Accrued	Loading Added

Arithmetic Operations

Mon, 01 Jan 0001 00:00:00 +0000

The calculator has a full four-function arithmetic engine built into the keypad. You can perform calculations on the active field just like a standard calculator.

Basic arithmetic

The four basic operators work as you would expect:

Button	Operator	Example	Result
`+`	Add	`100 + 50 =`	`150.00`
`−`	Subtract	`100 − 50 =`	`50.00`
`×`	Multiply	`100 × 3 =`	`300.00`
`÷`	Divide	`100 ÷ 3 =`	`33.33`

How chain calculations work

Enter a value on the active field.
Press an operator (+, −, ×, ÷).
Enter a second value.
Press = to compute the result.

The result replaces the value on the active field. The other two fields (Before/After/Amount) are then recalculated based on this new value.

Calculator

Mon, 01 Jan 0001 00:00:00 +0000

This page explains every element of the main calculator screen.

Screen layout

Main calculator screen

From top to bottom:

Menu toggle button and title.

Display Fields: Before, After, Amount with focus/anchoring. Active display is highlighted; all keyboard and keypad actions apply to the active field.

Error Display: When an error occurs, an error message is shown, replacing the display fields and nudge toolbar.

Nudge Toolbar: Shows the active field's name, up/down buttons to micro-adjust the active value within the valid calculation range, a direction toggle button, and the rate display with a selection slider.

Virtual keypad: This is where you enter your numbers and do basic arithmetic calculations.

Menu button (☰) — opens the slide-out drawer for navigating to Settings and About pages
Title — “3-Way Calculator”

Display fields

Three tappable fields show the current values:

F.A.Q.

Mon, 01 Jan 0001 00:00:00 +0000

General

What does the `+` / `−` button do?

It toggles between additive and subtractive calculation mode.

Additive (+): After = Before + (Before × rate) — for VAT, GST, sales tax, tips, commissions.
Subtractive (−): After = Before − (Before × rate) — for Zakat, discounts, depreciation, deductions.

Toggle freely — the focused field stays put and the other two recalculate.

Keyboard Shortcuts

Mon, 01 Jan 0001 00:00:00 +0000

When using the calculator on a desktop, laptop, or tablet web browser, you can use your physical keyboard for faster interaction. All keyboard input goes to the active display field.

Input

Key	Action
`0` – `9`	Enter the corresponding digit
`.`	Insert decimal point
`Backspace`	Delete the last character (backspace)
`Escape`	Clear all fields and reset (same as C button)
`C` or `c`	Clear all fields and reset (same as C button)

Arithmetic

Key	Action
`+`	Add operator
`-`	Subtract operator
`*`	Multiply operator
`/`	Divide operator
`%`	Percent (tax calculation or percentage of operand)
`Enter` or `=`	Evaluate / equals

Change which field is active (the anchor):

Speeding Up Invoice Sanity Checks: A Freelancer's Time-Saving Secret

Thu, 04 Jun 2026 00:00:00 +0000

For freelancers, administrative work is the ultimate unpaid tax. Every hour you spend writing invoices, chasing payments, sorting receipts, and calculating local taxes is an hour you cannot bill to clients.

One of the most tedious administrative tasks is the monthly billing audit.

Before you click “Send” on a client invoice generated by your accounting software, you must perform a “sanity check.”

Did the software calculate the VAT/tax correctly?
Do the line items sum to the exact gross total?
Are there any halala or cent mismatches that will cause the client’s automated payroll system to reject the invoice?

Here is the story of James, a freelance software developer, and how replacing spreadsheet audits with the 3-Way Calculator cut his monthly invoicing routine from two hours down to ten minutes.

Legal Disclaimer

Mon, 18 May 2026 00:00:00 +0000

Last Updated: May 18, 2026

By using the 3-Way Calculator application (“the App”) and the associated website (collectively, “the Service”), you acknowledge and agree to the following terms and conditions regarding liability and professional advice.

1. Not Financial or Professional Advice

The Service provides a tool for performing mathematical calculations based on user-defined rates. The results generated by the Service are for informational and educational purposes only.

The Service does not provide financial, tax, accounting, or legal advice. The calculations performed by the App do not constitute professional guidance, and the Service should not be relied upon as a substitute for consultation with qualified professional advisors.

Privacy Policy

Mon, 18 May 2026 00:00:00 +0000

Effective Date: May 18, 2026

This app is developed and published by Gazelle Soft Works.

The 3-Way Calculator (“the App”) is committed to protecting your privacy. This Privacy Policy explains our practices regarding the collection, use, and disclosure of information that is received through our App and website.

1. Information Collection and Use

1.1 Personal Data

The App is designed to be an “offline-first” tool. We do not require you to create an account, and we do not collect, store, or transmit any personally identifiable information (PII) such as your name, email address, phone number, or physical location.

Terms of Service

Mon, 18 May 2026 00:00:00 +0000

Effective Date: May 18, 2026

Please read these Terms of Service (“Terms”) carefully before using the 3-Way Calculator application (“the App”) or the website operated by Gazelle Soft Works (“us”, “we”, or “our”).

1. Acceptance of Terms

By accessing or using the App, you agree to be bound by these Terms. If you disagree with any part of the terms, then you may not access the App.

2. Description of Service

The 3-Way Calculator is a tool designed for performing tri-directional percentage calculations. The service is provided “as is” and “as available.”

The 'Wandering Values' Problem: Why Your Tax Calculator Is Lying to You

Mon, 18 May 2026 00:00:00 +0000

Have you ever been in a high-stakes negotiation, calculated a VAT-inclusive price, then tried to “reverse engineer” it back to the original net amount, only to find the numbers don’t match anymore?

One minute your total is $1,150.00, and the next, it’s $1,149.99. It seems like a penny, but in business, that penny represents a breakdown in mathematical integrity.

Welcome to the “Wandering Values” problem—the hidden ghost in the machine of standard percentage calculations.

Contact

Mon, 01 Jan 0001 00:00:00 +0000

Download Apps

Mon, 01 Jan 0001 00:00:00 +0000

How it Works

Mon, 01 Jan 0001 00:00:00 +0000

Mobile Apps Coming Soon

Mon, 01 Jan 0001 00:00:00 +0000

3-Way Calculator

Design Philosophy

1. Currency-agnostic

Rate Configuration

What is a flat rate?

Themes

Switching themes

Midnight Executive (default)

Use Cases

Example 1. Calculate VAT on a product price

Example 2. Find the price including tax (Before → After)

Getting Started

The three fields

Nudge Feature

Why nudge exists

Settings

Accessing Settings

Language

Terminology Reference

Tax & Core

Commerce

Finance & Insurance

Arithmetic Operations

Basic arithmetic

How chain calculations work

Calculator

Screen layout

From top to bottom:

Header

Display fields

F.A.Q.

General

What does the + / − button do?

Keyboard Shortcuts

Input

Arithmetic

Navigation

Speeding Up Invoice Sanity Checks: A Freelancer's Time-Saving Secret

Legal Disclaimer

1. Not Financial or Professional Advice

Privacy Policy

1. Information Collection and Use

1.1 Personal Data

Terms of Service

1. Acceptance of Terms

2. Description of Service

The 'Wandering Values' Problem: Why Your Tax Calculator Is Lying to You

Contact

Download Apps

How it Works

Mobile Apps Coming Soon

What does the `+` / `−` button do?