How I Built a Free Inflation Calculator for Vietnam's 2026 Oil Crisis

How I Built a Free Inflation Calculator for Vietnam's 2026 Oil Crisis
When oil prices crossed $100/barrel and gas prices in Vietnam surged overnight, I realized my personal finance tools needed to answer one urgent question: "How much is inflation actually eating my salary?"

The Problem
On March 7, 2026, Vietnam's fuel prices saw their largest single-day increase in years:

• RON 95-III gasoline jumped to 27,040 VND/liter (+4,700 VND)
• Diesel surged to 30,230 VND/liter (+7,200 VND)

This wasn't just about filling up your motorbike. It triggered a classic cost-push inflation domino:

Oil price ↑ → Transport costs ↑ → Raw materials ↑ → Consumer prices ↑ → Your purchasing power ↓

Vietnam's CPI for February 2026 had already rebounded to 3.35%, and forecasts pointed toward 4.5% by year-end. For someone earning 20 million VND/month (~$780 USD), that's roughly 10.8 million VND/year silently disappearing from their wallet.

I wanted to build a tool that makes this painfully visible.

The Stack
My fintech calculator ecosystem (Máy Tính Tài Chính) runs on:

Next.js 16 (Turbopack) — SSR for SEO, client-side interactivity for calculators
TypeScript — End-to-end type safety
Vanilla CSS — No Tailwind, full control over design tokens
Vercel — Edge deployment, 100/100 Lighthouse score
Building the Inflation vs Savings Calculator
The core logic is deceptively simple but financially important:

typescript

// Real purchasing power after inflation
const realValue = nominalValue / Math.pow(1 + inflationRate, years);
// Savings growth with compound interest  
const savingsGrowth = principal * Math.pow(1 + bankRate, years);
// The gap = how much you're actually losing
const purchasingPowerLoss = savingsGrowth - (savingsGrowth / Math.pow(1 + inflationRate, years));

The key insight: if your bank offers 5% interest but inflation is 4.5%, your real return is only 0.5%. On 100 million VND, that's just 500,000 VND of actual growth per year — barely enough for a dinner out.

You can try the live calculator here: Tiết Kiệm vs Lạm Phát Calculator

What I Learned About SEO for Financial Tools
Building 50+ calculators taught me that **utility pages rank differently **from blog posts:

Search intent is transactional — Users want to calculate, not read
Schema markup matters — SoftwareApplication schema gets rich snippets in Google
Internal linking is king — Each calculator links to 3-5 related tools, creating a "content mesh"
For the inflation crisis specifically, I wrote a deep-dive analysis on how rising oil prices impact Vietnamese household budgets, complete with real CPI data and a 5-step protection plan.

The Results

• Lighthouse Score: 100/100 Performance, Accessibility, Best Practices, SEO
• 50+ financial calculators covering tax, savings, investment, debt, retirement
• 27 blog posts targeting Vietnamese personal finance keywords
• Zero dependencies on external APIs for calculations (all client-side)

Try It Yourself
The entire ecosystem is free to use at maytinhtaichinh.com. Whether you're worried about how to protect your assets during the Iran conflict or just want to calculate your net salary after tax, there's a tool for that.

If you're building fintech tools or dealing with localized financial calculations, I'd love to hear about your approach. Drop a comment below!

If you're building fintech tools or dealing with localized financial calculations, I'd love to hear about your approach. Drop a comment below!