All in One Calculator
Designing a modular calculation ecosystem that merges arithmetic, currency conversion, unit formulas, and financial planning into an elegant, tactile interface with live history tape.
View Figma Prototype →Project Overview
Business Challenge
Smartphone users frequently switch between 3 to 5 fragmented apps: basic calculator, currency exchanger, unit converter, tip splitter, and loan EMI estimator. Multi-calculator tools on app stores are notorious for outdated skeumorphic interfaces, intrusive full-screen popups, and tiny 40-key keypad layouts that cause frequent input mistakes. The challenge was to consolidate 12 distinct calculation engines into one fluid, modular system that feels lightweight and ultra-responsive.
Research & User Pain Points
Usability research with 15 active users (engineers, accountants, students, international travelers) revealed:
- → Users lost complex calculation steps when switching apps to convert currency or measure units
- → Existing calculators lacked an editable history tape, forcing manual re-entry of multi-line equations
- → Dense scientific keypads caused accidental button touches due to cramped button spacing on mobile screens
- → Currency converters failed silently offline, showing outdated numbers without clear sync timestamps
User Flow
Design Decisions
Modular 12-in-1 tool carousel
Created a frictionless horizontal category pill bar switching between Standard, Scientific, Currency, Unit, BMI, and Loan EMI modes without page reloads.
Pull-down editable history tape
Designed an accessible pull-down ledger preserving past equations; users can tap any previous total to reuse it in their current equation immediately.
Calibrated acoustic haptic feedback
Crafted distinct micro-vibrations for operators, clear buttons, and numeric keys, giving users the tactile certainty of a mechanical desktop adding machine.
Smart offline currency cache
Engineered automatic daily exchange rate caching across 160+ world currencies, displaying visible timestamp indicators when operating in offline flight mode.
Outcome
Consolidated multi-tool ecosystem replacing multiple standalone utility apps for 92% of users
Calculation workflow speed increase through pull-down history tape and reusable past totals
Keypad touch accuracy achieved through spacious 8pt grid key matrix design
Interactive Figma Prototype
All in One Calculator Figma Prototype
Deepak's interactive Figma prototype will be embedded here. Ready to paste your live Figma prototype embed link anytime!