How do I save my calculations?

Your open tabs and their inputs save automatically as you work. To keep a particular result in your history, click the save icon or press Cmd/Ctrl + S. You can view, restore, or export your history from the right-hand panel.

Workspaces are separate environments for your calculations. You can create different workspaces for different projects (e.g., "Personal Finance", "Physics Homework") to keep your tabs and history separate. Custom variables are shared across every workspace.

Can I use my own variables?

Yes. You can create custom global variables (like "tax_rate" or "height") from the Variables tab in the right-hand panel. These variables can then be used in any calculator field: click into it, then the variable icon at its right end. That saves re-typing common values.

How do I find the right calculator quickly?

Use global search (press the search shortcut or click the search bar) and type what you need — for example "loan", "BMI", or "percentage". Results match calculator names and related terms, so you can jump straight to the tool. You can also browse by category from the "All Tools" button in the header, or from the Explore by Category cards on your Dashboard, where calculators are grouped into finance, health, math, engineering, and more.

CalcTrail User Guide

Welcome to CalcTrail

CalcTrail is a free set of calculators and converters for finance, health, engineering, AI costs, marketing, design, grades, dates and times, and everyday math. You can open several at once in tabs, keep the results you want in your history, share a result with a link, and find any calculator with global search. This guide walks through how each part works.

1. The Main Interface

The CalcTrail interface has three main parts:

Header (top): Your brand button jumps to the Dashboard. The All Tools button opens a category mega-menu on desktop; on tablet and mobile the same button opens global search already filtered to the full tool list. Search, account, and sign-in live here too. On tablet and mobile, a menu icon opens a drawer with the same navigation.
Tab Bar & Main Area: The tab bar (just below the header) lists your open calculator tabs so you can switch between them. When no tabs are open, this area shows the Dashboard.
History & Variables: On tablets and desktops, small icon buttons anchored to the right edge of the screen open your saved calculation history and custom variables — each shows a count badge. On phones, the panel icon () in the header opens the same panel. The Ctrl or ⌘ + Shift + H shortcut works on both.

2. The Calculator Library

Calculators and converters, by category

Beyond standard arithmetic, CalcTrail has specialized calculators for specific tasks. Here is every tool, by category:

Math & Conversions: the Basic, Scientific, and RPN calculators; Percentage, Fraction, and Ratio calculators; and the Unit Converter.
Engineering: Ohm's Law, Power, Wire Gauge, Resistor Color Code, Stress & Strain, Beam Deflection, Concrete Volume, Pipe Flow, and LC Circuit calculators.
Finance & Business: Loan, Car Loan, Mortgage, Savings, Investment, Retirement, 401(k), Roth IRA, CD, APY, Present Value, Payback Period, Break-Even, Markup/Margin, Debt-to-Income (DTI) Ratio, Credit Card Payoff, Tip, Discount, Sales Tax, VAT, and Fuel Cost calculators, plus Unit Price Comparison.
Health & Fitness: BMI, Calorie, TDEE, Macro, Body Fat, Pace, and Water Intake calculators to track your wellness goals.
Date & Time: the Age, Date Difference, Time and Time Card calculators, and the Time Zone Converter.
Academic: GPA, Grade, Final Grade and Weighted Mean calculators for students and educators.
Design & Creative: the Aspect Ratio calculator and the Color Converter, for designers and developers.
Marketing: ROI, ROAS, CPM, CPC, CLV, and CAC calculators for evaluating returns, ad spend, and customer value.
AI & Machine Learning: LLM Token Cost, Image Generation Cost, and Speech Cost calculators for estimating what a model or API call will cost; the Token Converter for turning text or a word count into tokens; and AI ROI for weighing an AI tool subscription against the time it saves.

A few of them in more detail:

Basic Calculator: Standard arithmetic with a tape you can work with — edit any line and it recomputes, tag and note lines for a searchable record, send the running total back to the display — plus receipt-style print and JSON/CSV/PDF export, desk-calculator percent (200 + 10% is 220), and memory keys (M+/M-/MR/MC).
Scientific Calculator: Advanced mathematical functions including trigonometry (sin, cos, tan, inverses), logarithms (log, ln), exponentials (eˣ, 10ˣ), power and root functions (xʸ, √, x², x³, ∛, 1/x, |x|), factorial (!), hyperbolic functions (sinh, cosh, tanh, inverses), and a constants library (π, e, φ, c, h, NA). Degrees, radians or gradians, an EE key for scientific-notation entry, and a display format control — Fixed, Scientific or Engineering with a digits setting — for reporting results to a set number of decimal places, plus a searchable session history you can copy, reuse or save as a variable from.
RPN Calculator: For engineers and scientists who prefer stack-based Reverse Polish Notation, similar to classic HP calculators — SWAP, ROLL, DROP and LAST X, four memory registers, operation replay, a searchable session history, degrees/radians/gradians for the trig keys, and Fixed, Scientific or Engineering precision modes.
Unit Converter: Convert between units with a multi-unit view showing every unit in the category at once, one-click popular pairs, quick swap, and a decimals control for how precisely results are shown. Covers cooking measures (US and metric cups, spoons, sticks of butter, Gas Mark) and fuel economy (mpg US/UK, L/100km, km/L) alongside the usual length, weight, volume and data categories. You can also type a whole conversion on one line, such as "12 in to cm".
Financial Calculators: Loan and Mortgage, both with a refinance break-even; Mortgage also with a rent vs. buy comparison; Investment with strategy comparison and risk analysis; and Savings with goal-based planning.
Unit Price Comparison: Find the best deal while shopping by comparing multiple items with different prices, quantities, and units.
Health & Fitness: BMI with a reverse mode for a target weight, and Calorie with macro visualization and calorie cycling.
Time Calculator: Add and subtract hours, minutes and seconds across as many rows as you need, or switch to Time Card mode to total shifts from clock-in and clock-out times with unpaid breaks — including overnight shifts — in both hours:minutes and payroll decimal hours.
Time Card: Total a week or two of shifts, with lunch breaks, overnight and split shifts, and see regular hours, weekly or California-style daily overtime, gross pay, and what it comes to per month and per year.
Time Zone Converter: Plan a meeting across up to 20 places on one timeline, on the date you choose, with each place's live local time.
Date Difference: Calculate date differences with business days calculator (excluding weekends and holidays) and quick date presets.

3. The Dashboard

The Dashboard is what you see when you first open CalcTrail, or after you close all your tabs.

Continue Where You Left Off: If you had a calculator open last time, a dismissible card offers to resume it — the Dashboard always shows first, so a direct link to a specific calculator is never silently overridden by an old session.
Explore by Category: Browse the full tool library grouped by category, with a tool count and a preview of the tools in each.
Popular & Featured Tools: a starting set, replaced by your own most-used tools once you have used four or more.
Recent History: A snapshot of your most recent saved calculations within the current workspace. Click any entry to restore it.

4. Workspaces: One per Project

Workspace Management

Workspaces keep your projects apart. Each one has its own open tabs and its own history (e.g., "Work Projects", "Personal Finance").

Switching: Use the workspace menu in the header (in the main menu on phones) to switch between workspaces.
Managing: Choose "Manage Workspaces" in that menu to create, edit, and delete workspaces.

5. The History Panel: Save a Calculation and Come Back to It

Saved calculations

The history panel holds the calculations you choose to keep, within the currently active workspace. Nothing lands there on its own — you save an entry when a result is worth returning to, and it stays until you delete it.

Saving: Click the Save icon inside a calculator or press Ctrl or ⌘ + S to save the current state and result.
Restoring: Click "Restore" on any history item. If that calculator is already open in a tab, you'll be asked whether to replace it or open a new one; otherwise it opens directly in a new tab, clearly marked "Restored." Change a restored tab and a "Save changes to history" prompt appears; saving updates that same history entry rather than adding a new one.
Tagging & Filtering: Add custom tags to history items for organization. You can then filter your history by clicking on the tags at the top of the panel.
Export: Export the current workspace's history to a JSON file for backup, using the button at the bottom of the history panel. History cannot be imported back; Settings → Plan & Data restores a full backup instead.

6. Custom Variables: Your Personal Constants

Reusable Variables

Custom variables allow you to store and reuse numbers across different calculators, saving you time and reducing errors.

Creating Variables: Go to the "Variables" tab in the right-hand panel and click "Create". Each variable needs a unique name (e.g., tax_rate) and a value — a number, a date, text or JSON.
Snippets: In the Token Converter, "Snippets" beside a text box saves its text as a variable and inserts a saved text or JSON variable where the cursor is.
Global Variables: Variables are global to your profile, so they stay available across all workspaces.
Using Variables: Click into a calculator field and the variable icon () appears at its right end; click it to insert a variable's value.
Importing Variables: With a free account, you can bulk-import variables from a CSV file using the "Import" button in the Variables panel.
Values From Other Tabs: The same button, at the right end of most number fields once you click into one, also has an "Open Tabs" view, listing the inputs and results of the other tabs you have opened this session, so you can use one of those numbers without retyping it. Tabs on the same subject as your field come first, anything from another subject is marked, and a search box finds a figure across all of them. Click a row to insert it; the value is copied, not linked. To keep a number for next time, insert it and then create a variable from the field — the form opens with that number already in it.
Sending A Result The Other Way: Beside a result, the copy button grows an arrow when another calculator can use that number. It lists where the number fits — your open tabs first, then calculators you can open for it — and shows what each field holds now and any change of mode the tab will make. Rows the receiving calculator would reject, such as a figure above its limit or a weight in the wrong unit system, are marked instead of sent.
Continuing In Another Calculator: On calculators that have it, the result panel ends with "Continue in another calculator", which moves a whole calculation on rather than one number. Each row names a calculator that can carry on from your entries and says what it will do with them first — how many fields it fills, and how many of those already hold something — with the tabs you have open listed before the ones a new tab would start. Wherever a value lands it is highlighted and scrolled into view, and with a mouse or trackpad it takes the keyboard focus so you can carry straight on.

7. Global Search

Press Ctrl or ⌘ + K

Global Search is one search box for tools, your saved history, variables and workspaces, and for commands — all usable without leaving the keyboard.

Find a tool: Type its name, or another name for it such as amortization or gratuity, and pick it from the Tools group.
Search your data: Find saved history entries in the current workspace by title, description or tag, look up custom variables by name or unit, and switch between workspaces — all from the same search box.
Commands: Type > to access system commands like >theme dark, >new variable, >shortcuts, or >settings.
Scopes: >tools narrows the search to the full tool catalogue, and >tabs narrows it to the tabs you already have open. The active scope shows as a chip in the search box — remove it to search everything again.
Create a variable from search: Type >var rate = 5 and press Enter to create a number variable without opening the variables form.
Before you type: Open Global Search without typing and you'll see your recent searches, recent history (for the calculator you are in, when it has any), your recent variables, and a short list of popular tools.
How results are ordered: Results are scored by how well they match — a missing letter is tolerated — and shown in groups: variables, history, workspaces, then tools. Commands appear when you type >, and open tabs with >tabs.
Recent Searches: Your last few searches stay in this browser and appear as suggestions when you open the search box, whether or not you are signed in. They are never sent to our servers. Clear the list from the search window, or turn saving off in Settings → Search.

8. Keyboard Shortcuts

The ones you will use most

Most everyday actions have a keyboard shortcut; press the question-mark key (?) outside a text field for the full list. Tabs: Ctrl or ⌘ + 1–9 to switch, Esc to close the one you are in. Your work: Ctrl or ⌘ + S to save, Ctrl or ⌘ + Z to undo, Ctrl or ⌘ + Shift + R to reset. On the Basic and Scientific calculators, type with the number keys and press Enter or = for the answer.

9. Signing In & Account Management

Creating and Managing Your Account

You can sign up with an email and password (verified by email) or with Google Sign-In, which verifies your email automatically — you can add a password later if you want both options. Change or set your password from the Profile tab in Settings.

10. Plan Limits & Features

Understanding Your Plan

Guest Users: 5 workspaces, 10 tabs per workspace, 50 history entries per workspace, 25 global variables. Free Plan (Logged In): 10 workspaces, 20 tabs per workspace, 100 history entries per workspace, 100 global variables. Every calculator works on both, and JSON, CSV and PDF export are open to everyone. An account adds cross-device sync and the complete multi-row export tables — full amortization schedules, full comparisons, and the full tape or session from the keypad calculators (see section 12).

11. Settings & Data Management

Customization

Open Settings from the gear button in the header (in the main menu on phones), or from your account menu once you are signed in. The tabs are General & Appearance (theme, interface density, font size), Formatting, Search (including the switch that turns off saving recent searches), Plan & Data (usage against your plan limits, backup and restore, and the Danger Zone), and Analytics (the analytics on/off switch). Profile appears once you are signed in. In the Danger Zone a guest can reset everything CalcTrail keeps in the browser; signed in, you can reset your data (the account, plan and share links stay) or delete the account itself. Each lists what goes before anything is removed, and offers a backup first.

12. Export & Import Features

Data Export & Import (PDF/CSV)

Every calculator exports its results as JSON, CSV or a PDF report, with no account needed. Signing in only adds the complete multi-row tables: signed out, a long table — an amortization schedule, a comparison, a keypad calculator's tape or session — exports its first 10 rows, with a note saying how many remain. Going the other way, custom variables can be imported from a CSV file with a free account — handy for bringing in values you already keep in a spreadsheet.

13. Related Calculators & Discovery

Related calculators

Each calculator lists related calculators at the bottom of its page. Click one to open it.

14. More Features

Calculator Features

Values From Other Tabs: Most number fields can read the inputs and results of your other open tabs. Click into a field, then the button at its right end, open "Open Tabs", and pick a value — a mortgage payment for a debt-to-income field, a maintenance calorie figure for a macro split. The number is copied, not linked.
Continue in Another Calculator: Some calculators end their result panel with "Continue in another calculator", which opens the next calculator with your numbers already in it.
Comparison & What-If Tools: Some calculators compare options within one page — several loans side by side, investment strategies, refinance break-even — and some have what-if panels that show how the result moves with one input.
Sharing: The Share button in a calculator's header makes a link to what you see: one that carries the values in its address and does not expire, or an expiring view-only link. Shareable Calculations explains both.
Monte Carlo Simulation: The Investment calculator includes a Monte Carlo simulation that models how outcomes vary under market uncertainty.
Quick Start & Examples: The form calculators and the Scientific calculator carry worked examples you can load with one click, and every calculator has a Quick Start guide below it.

15. Privacy & Security

How your data is handled

Connections use HTTPS, and signed-in data is stored encrypted on our servers. As a guest, your data stays in your browser; creating an expiring share link sends that one calculation to us. You can export everything you have from Settings → Plan & Data, and delete your account yourself in its Danger Zone, which removes the account and everything in it at once (email us if you cannot sign in). CalcTrail is operated from India, where the Digital Personal Data Protection Act, 2023 governs personal data, and we give everyone the same rights, wherever they live: access, correction, deletion, export, objection and withdrawal of consent. The Privacy Policy sets out each one, and what is collected for it.

Frequently Asked Questions

No. CalcTrail is a website and needs a connection to open a page. The maths runs in your browser, so a calculator you already have open keeps responding if your connection drops, but the app is not built for offline use, and saving to your account needs a connection.