Calto - Write like a memo, calculate like a pro

Problem

The limitations

🧮

Traditional Calculator

Can't remember intermediate results, lacks context for complex calculations.

📊

Spreadsheets

Uncomfortable on mobile, overly complex for simple calculations.

📝

Note Apps

No calculation features - you end up opening a calculator anyway.

Solution

Calto solves it

coffee = 4500

lunch = 12000

dinner = 8500

---

daily expense = sum → 25,000

# Currency operations

apple = $1

apple + 4 → $5

apple in won → ₩1,350

Natural as note-taking

Intuitive calculations with variable names

Context preserved

Reuse previous results as variables

Mobile optimized

Great UX even on small screens

Powerful Features

Skip the complex buttons, just write what you think.
Calto handles the rest.

⚡

Real-time Calculation

Results appear within 16ms as you type. Natural expressions like 20% of 5000 just work.

🏷️

Named Variables

Define variables naturally like "coffee = 4500" and use scale notation like 2.5M or 100k.

📐

Unit Conversion

Supports 66 units like 10cm in inch, 5kg in lb. Convert length, weight, temperature, volume, speed, data rate and more.

💱

Currency Operations

Supports 6 currencies (USD, KRW, EUR, JPY, CNY, GBP). Mix operations like 100 USD + 50000 KRW. Convert aggregates with sum in won.

📅

Date Calculation

Calculate dates like today + 30days, 2026-01-01 - today. Compound time like 2h 5min is supported.

📊

Section Aggregation

Calculate sums and averages with sum, avg. Currency is automatically preserved when included.

✨

Smart Autocomplete

VS Code-style popup for quick input of variables you defined. Suggestions appear right below your cursor.

⌨️

Accessory Bar

Quick access to 5 operators (+, ×, -, =, in) with a More popup for extra symbols. Fully customizable with Main/More group swap and reorder.

⚖️

Ratio & Proportion

Solve proportions like a : b = c : ? automatically. Great for recipes, scale models, and unit pricing.

🪙

Cryptocurrency

Real-time rates for BTC, ETH and more. Convert between crypto and fiat currencies seamlessly.

Perfect for these situations

Make everyday calculations easier with Calto

Travel Budget

Organize flights, hotels, meals at a glance with auto currency conversion

flight = $450

hotel = $120 × 5nights → 600

food = $50 × 5days → 250

---

sum in KRW → ₩1,755,000

Quick Meeting Math

Estimate project costs and budget allocation in real-time

development = $30000

design = $8000

marketing = $5000

---

total budget = sum → $43,000

Shopping Total

Track your cart total and stay within budget instantly

milk = 3.20

eggs = 6.50

fruits = 12.00

---

sum → $21.70

All Features, Free for Now

Every feature is currently available for free.
A premium plan may be introduced in the future.

Currently Free

Free all features — currently free

Real-time calculation (<16ms)
Named variables (Korean supported)
Unit conversion (66 units)
Date & compound time (2h 5min)
Ratio & proportion (a : b = c : ?)
Natural language (20% of 5000)
Scale notation (k/M/B)
sum/avg aggregation
Live exchange rates (6 currencies)
Cryptocurrency rates (BTC, ETH)
Unlimited documents
Accessory Bar
6 built-in themes

A premium plan may be added in the future. Core calculation features will always remain free.

Get Started Free

Frequently Asked Questions

Have questions?

What calculations does Calto support?

Basic arithmetic, percentages (20% of 5000), parentheses, named variables, scale notation (k/M/B), unit conversion (66 units across 7 categories), currency operations (6 currencies), date & compound time (2h 5min), ratio & proportion (a : b = c : ?), cryptocurrency (BTC, ETH), and sum/avg aggregation.

How do currency operations work?

Store currency in variables like "apple = $1", and perform mixed operations like "$1 + 4 = $5". Currency is automatically preserved in sum/avg, and you can convert with "sum in won".

Can I use Korean variable names?

Yes! You can name variables in Korean, like "김치 = 10,000". Write your calculations as naturally as taking notes.

Does it work offline?

Yes, all basic calculations and unit conversions work offline. Only exchange rates and cryptocurrency rates require an internet connection.

Is Calto free?

For now, every feature is available for free — real-time calculation, variables, 66-unit conversion, date math, ratio & proportion, cryptocurrency, live exchange rates, unlimited documents, and 6 built-in themes. A premium plan may be introduced in the future, but core calculation features will always remain free.

Can't find your answer?