Calculator: Simple Calculator

Review by eFreeware

Anyone who reaches for a calculator several times a day, and would rather not open four different apps to do it, is the sort of person this one is built for. Calculator: Simple Calculator comes from Efficient Tools and gathers basic and scientific arithmetic, unit and currency conversion, and a handful of everyday money and date calculators into a single free Android download. The pitch is breadth: one place for the sums that come up at a desk, in a store or at the kitchen table.

What makes that appealing is how ordinary the tasks are. You might be splitting a restaurant bill, working out what a jacket costs after a discount and tax, converting a measurement from a recipe, or checking what a loan payment looks like before signing anything. None of those needs a specialist app, but each of them needs something, and having them in one spot saves the small friction of hunting around.

The app is free to install and supported by ads. There are no in-app purchases, so nothing inside is gated behind a payment. It has been downloaded more than 50 million times and holds a 4.3 average from 129,139 ratings, which tells you it has found a wide audience rather than a niche one.

Everyday arithmetic with a scientific layer underneath

The core is a calculator that handles the four basic operations along with squares, roots, parentheses and percentages. That covers the bulk of what most people do day to day, and the percentage support is the piece I would lean on most, since so many practical questions come down to working out a proportion of something.

A scientific layer adds logarithms, natural logarithms, square roots and the sine, cosine and tangent functions. It is the sort of set that gets a student through homework or helps someone check a figure without reaching for a separate scientific tool.

Two smaller touches matter more than they sound. You can move the cursor anywhere in an equation to edit or copy part of it, which is the difference between fixing a mistyped number and starting the whole sum again. And you can set the precision anywhere from zero to ten decimal places, so the same app can give you a clean whole number for a shopping total or a longer figure for something technical.

History that survives a slip of the thumb

Calculations are saved in real time, and the developer says you can pick them up from the history even if the app is closed by accident. That is a modest feature that turns out to be useful in practice: the moment you realize you needed the previous result, or want to confirm how you arrived at a number, it is still there.

I would expect this to matter most to people who use a calculator as a working record rather than a one-off tool. If you are totaling expenses, checking a series of conversions or comparing a few loan scenarios, being able to look back at the steps is more valuable than the arithmetic itself. It also means a stray back gesture does not wipe out a chain of work.

The app runs offline for its calculator functions, which the developer presents as a selling point. That fits the way most people use a calculator: quickly, wherever they happen to be, without waiting on a connection.

Conversions for measurements and money

The unit converter covers length, area, volume, weight, time and data. That is a sensible spread for daily life rather than an exhaustive engineering reference. Converting a recipe's volume, a package's weight or a file's data size are the kinds of jobs it is aimed at, and having them next to the calculator means you can convert a figure and then keep working with it.

The currency side pulls in exchange rates and lets you convert four currencies at once. That multi-currency view is the interesting part: rather than converting one amount and repeating the process, you can compare several at a glance, which suits anyone weighing prices in more than one currency before deciding.

Between the two converters, the app covers the conversions that come up most often outside of specialist work. It is not trying to be a reference for every unit in existence, and it does not need to be.

The money and date calculators

A discount calculator takes an amount, a discount rate and a tax rate and returns the savings, the tax and the final total. That is a tidy way to answer the question of what something actually costs once the price tag stops being the whole story, whether you are shopping a sale or pricing something you sell.

The GST calculator works from an original cost and a tax rate to give a total price, which is the same idea in a simpler form for anyone who deals with that tax regularly. The loan calculator takes an interest rate and a principal and supports arrangements such as equal principal and equal installments, so you can see how a repayment plan is shaped before committing to it.

The tip calculator asks for a bill amount and a tip percentage and returns the tip, with an option to leave the tip out of the taxable amount, and it divides the final amount evenly so each person's share is clear. The date calculator handles date arithmetic and the gap between two dates. Together these are the small, recurring sums that rarely justify their own app but are annoying to do by hand.

What the free version actually involves

The app costs nothing to download and is ad-supported. There are no in-app purchases, so the ad support is how it is funded rather than a route to a paid tier. I would set expectations accordingly: a free tool with this much packed into it is going to carry advertising, and that is the trade being offered.

For anyone who wants a single free app to cover arithmetic, conversions and the common money sums, the arrangement is straightforward.

The app carries an Everyone content rating and has been updated as recently as September 11, 2026, having first been released on September 15, 2023. A recent update suggests the developer is still working on it rather than leaving it as it was.

How it compares with the alternatives

The obvious comparison is the calculator that already came with your phone. A built-in app is instant and uncluttered, and for plain arithmetic it is hard to beat. What this app adds is the surrounding set: scientific functions, the unit and currency converters, and the discount, GST, loan, date and tip calculators in the same place.

The other comparison is a dedicated converter or a finance app. Those tend to go deeper on one job, with more units or more detailed loan modeling, but they cover one job each. This app is the opposite bet: broad coverage of common tasks in a single download, with each individual tool kept simple.

That is the honest shape of the choice. If your calculating is almost entirely addition and subtraction, the app you already have will do. If you regularly find yourself converting units, checking a currency, working out a discount or splitting a bill, having all of it in one place is the reason to consider this one.

A broad, free toolkit for routine number work

Calculator: Simple Calculator is worth installing if you want one free Android app that covers the arithmetic, conversions and everyday money sums you run into during a normal week.

The trade-offs are the ones you would expect. It is ad-supported, and it is broad rather than deep, so someone who needs exhaustive unit coverage or detailed financial modeling will find each individual tool goes only as far as its job requires. The large keyboard, optional key vibrations and saved history are the details that make it comfortable for regular use.

For students, shoppers, travelers and anyone who handles household finances, this is a sensible free addition to a phone. With more than 50 million installs behind it, it has already proven itself the kind of app people keep around.