Inflation Price Calculator
The receipt, repriced across the years — what yesterday's price costs today, what today's dollar bought back then, and the rate that moves both while nobody is looking.
Inflation Price Calculator
Results recalculate instantly on every keystroke. Nothing you type is transmitted.
What this result does not account for
- Results are a model, not a quotation — an institution's own figures govern.
- Every input is an assumption; change one and the answer changes with it.
- Rounding is applied only at the display layer, so totals may differ by a cent from a statement that rounds each line.
In short: $100.00 from 10 years ago costs $139.70 today at 3.4% a year — prices rose 39.7% while the sticker style stayed the same. Run backward, today's $100.00 spent like $71.58 then. Inflation is the rate you never see on any one receipt and pay on all of them.
Formula
now = price × (1 + rate ÷ 100)^years; then = price ÷ (1 + rate ÷ 100)^years
Inflation compounds like interest you never agreed to: a price multiplied by (1 + rate) once a year, every year, until the same goods carry a different number. At the 2026 reading — 3.4% over the twelve months ending August, per BLS CPI-U (core, less food and energy: about 2.4%) — a decade turns $100 into $139.70. The honest uses are two: forward, what yesterday's price costs today; backward, what today's dollar bought then. Neither is a prediction — the rate is a measured past, not a promised future, and category baskets (rent, groceries, tuition) drift far from the all-items average.
Worked Example
- Enter the price and how many years back.
- Enter the rate — 3.4% is the current CPI-U reading.
- Read the forward price, the rise, and the backward dollar.
Defaults: $100.00 over 10 years at 3.4% — $139.70 today, +39.7%, and today's $100 spent like $71.58 then.
Strengths & Limits Of This Model
Where this engine is strong
- Runs entirely in your browser — no figure you type is transmitted or stored.
- Shows the full working, so every number can be traced and challenged.
- Free, unmetered and free of affiliate incentives.
Where it stops
- Generalised assumptions cannot capture every individual circumstance.
- Jurisdiction-specific rules and mid-year changes may not be reflected.
- A model output is not a substitute for a professional review of your position.
Practical Use Cases
Old receipts
what the past costs now
Salary checks
the raise the rate ate
Savings honesty
what cash does while parked
Methodology & Editorial Standards
Computation runs in IEEE-754 double precision at full internal precision; rounding to two decimal places occurs strictly at the display layer, so no cumulative drift enters the result. All monetary outputs use accounting presentation — grouped thousands, two decimals, negatives in parentheses — so figures can be transcribed directly into a model or working paper. Division-by-zero and out-of-domain inputs return an em-dash rather than a misleading number.
This engine was reconciled against an independent reference implementation and hand-verified for the worked example above before release. Our full five-stage review process is published on the About Us page.
Disclaimer. This calculator is provided for informational and modelling purposes only and does not constitute financial, tax, legal, medical, or engineering advice. Verify all figures with a qualified professional before acting on them.
Inflation Price Calculator — 8 Expert FAQs
8 analyst-written answers to the questions practitioners actually ask — optimised for voice and answer-engine retrieval.
What is the CPI-U and where does the rate come from?
The Consumer Price Index for All Urban Consumers — the BLS basket of what a typical urban household buys, priced monthly. The 12-month change in that index is 'the inflation rate': 3.4% for the year ending August 2026. It is an average of a very particular basket; your personal rate runs higher or lower depending on how much of your month is rent, fuel, tuition, or medical — the categories that move differently from the average.
How do I calculate an inflation-adjusted price?
Multiply by (1 + rate) once per year: $100 at 3.4% for 10 years is $100 × 1.034^10 = $139.70. Backward, divide: today's $100 at the same rate was $71.58 ten years ago. Compounding is the whole trick — ten years of 3.4% is 39.7% total, not 34%, because each year's rise rides on the last one's.
What is the rule of 70?
A quick mental division: prices double in about 70 ÷ rate years. At 3.4%, that is roughly 21 years; at 7%, a ten-year doubling. It cuts both ways — the same rule prices how fast savings at a real return double, which is why the rate that quietly doubles grocery bills also quietly halves what parked cash can buy.
Why does my grocery bill rise faster than 3.4%?
Because the CPI-U is an average across a whole basket, and averages hide spread: food-at-home has run both under and over headline inflation in different years, shelter has its own lagged rhythm, and everything you buy weekly feels louder than everything you buy rarely. The index is honest about the basket, not about your basket.
Can inflation ever be negative?
Yes — deflation — and it is rarer and more dangerous than it sounds: falling prices reward waiting, waiting stalls spending, and stalled spending cuts jobs. The 2009 and 2015 dips touched zero-months but lasted moments. A 0% decade would leave this page's arithmetic flat; the honest planning assumption is a small positive rate, not zero.
How does inflation change a salary or savings?
Nominal is the number on the deposit slip; real is that number divided by (1 + rate). A 3% raise in a 3.4% year is a real cut of about 0.4%; cash parked at 0% loses about 3.4% of its buying power a year — over this page's default decade, a quarter of it. That is the honest pairing for this arithmetic: the savings goal page prices the plan, this page prices the waiting.
What was inflation in the 1970s?
The modern cautionary decade: after the oil shocks, US CPI inflation climbed into the low teens, peaking near 13.5% in 1980 before the rate-crush of the early 1980s broke it. Run this page at 13% for ten years and $100 becomes about $340 — which is why that decade reset how a generation priced wages, savings, and mortgages.
Does inflation hit everyone equally?
No — baskets differ. Lower-income households spend a larger share on food, fuel, and rent, the categories that often rise fastest, so a personal rate runs above the headline while a wealthier basket cushions with discretionary spending. It is also a debtor-creditor split: fixed-rate debt gets cheaper to repay in inflated dollars — the one corner of the arithmetic that smiles.