Why this matters: Inflation silently erodes the purchasing power of your savings. ₹1 lakh today will buy less in future if prices rise—so knowing how to calculate inflation's impact and plan for real returns (after inflation) is essential for retirement planning, goal saving and preserving wealth.
Try the tool: Open Inflation Calculator
Key concepts — nominal vs real
- Nominal value/return: The face value increase not adjusted for inflation (e.g., bank interest 7% p.a.).
- Real value/return: The return after adjusting for inflation — measures change in purchasing power.
- Inflation rate (g): The annual rate at which general price levels rise (e.g., 6% p.a.).
Core formulas
Future cost (what a present amount will become):
Future Value (FV) = Present Value (PV) × (1 + g)^n
Purchasing power (real value) of a future amount back to today:
Real Value Today = Future Amount ÷ (1 + g)^n
Convert nominal return to real return:
Real return r_real = (1 + r_nominal) / (1 + g) − 1
Approximation (small rates): r_real ≈ r_nominal − g (useful but less accurate when rates are high)
Worked example A — How inflation erodes purchasing power
Scenario: You have ₹100,000 today. Inflation = 6% p.a. How much will ₹100,000 be worth in 10 years (in nominal rupees), and what will be its purchasing power relative to today?
Step-by-step (digit-by-digit):
Present Value (PV) = ₹100,000
Inflation g = 6% = 0.06
Years n = 10
Compute (1 + g)^n:
1 + g = 1 + 0.06 = 1.06
1.06^2 = 1.06 × 1.06 = 1.1236
1.06^3 = 1.1236 × 1.06 = 1.191016
1.06^4 = 1.191016 × 1.06 = 1.26247696
1.06^5 = 1.26247696 × 1.06 = 1.3382255776
1.06^6 = 1.3382255776 × 1.06 = 1.418519112256
1.06^7 = 1.418519112256 × 1.06 = 1.50363025899136
1.06^8 = 1.50363025899136 × 1.06 = 1.5938470745308416
1.06^9 = 1.5938470745308416 × 1.06 = 1.6894778980026927
1.06^10 = 1.6894778980026927 × 1.06 = 1.7908465718828542
Future Value (FV) = PV × (1 + g)^n
FV = 100,000 × 1.7908465718828542 ≈ ₹179,084.66
Purchasing power of ₹100,000 in 10 years relative to today:
Real Value Today = 100,000 ÷ 1.7908465718828542 ≈ ₹55,839.53
(So ₹100,000 today would have the buying power of only ~₹55,840 in 10 years if prices grow at 6% p.a.)
Worked example B — Nominal growth vs real growth
Scenario: You invest ₹100,000 at nominal return 10% p.a. for 10 years. Inflation is 6% p.a. What is the nominal future amount and its real purchasing power (in today's rupees)?
Step-by-step:
PV = ₹100,000
Nominal rate r = 10% = 0.10
Inflation g = 6% = 0.06
n = 10
Compute nominal growth (1 + r)^n:
1.10^2 = 1.21
1.10^3 = 1.331
1.10^4 = 1.4641
1.10^5 = 1.61051
1.10^6 = 1.771561
1.10^7 = 1.9487171
1.10^8 = 2.14358881
1.10^9 = 2.357947691
1.10^10 = 2.5937424601
Nominal FV = 100,000 × 2.5937424601 ≈ ₹259,374.25
Now convert nominal FV to today's purchasing power by dividing by inflation factor (1.06^10 = 1.7908465718828542):
Real purchasing power = 259,374.25 ÷ 1.7908465718828542 ≈ ₹144,800.00
Interpretation:
- Nominal amount grows to ≈ ₹2.59 lakh.
- In today's terms (after inflation adjustment), that ₹2.59 lakh buys about ₹1.45 lakh worth of today's goods — the real gain over ₹100,000 is ≈ ₹44,800 in today's rupees.
Real return calculation (exact formula)
Exact real return = (1 + r_nominal) ÷ (1 + g) − 1
For r_nominal = 10% and g = 6%:
(1 + r_nominal) ÷ (1 + g) = 1.10 ÷ 1.06 ≈ 1.0377358490566038
Real return = 1.0377358490566038 − 1 = 0.03773584905660377 ≈ 3.77% p.a.
Note: Approximation (r_nominal − g) gives 4% (close but not exact).
Rule of 72 — how fast prices double
Use the Rule of 72 to estimate how many years it takes for prices to double at a given inflation rate:
Years to double ≈ 72 ÷ inflation_rate(%)
Example: At 6% inflation → 72 ÷ 6 = 12 years (prices double in about 12 years).
Comparison table — Nominal vs Real outcomes
| Scenario | Nominal result after 10 years | Real purchasing power in today's rupees |
|---|---|---|
| Keep cash ₹100,000 (0% nominal return) | Still ₹100,000 | ₹55,839 (after 6% p.a. inflation) |
| Invest at 7% nominal | FV ≈ ₹196,715 (100,000 × 1.07^10) | Real ≈ ₹109,746 (196,715 ÷ 1.06^10) |
| Invest at 10% nominal | FV ≈ ₹259,374 (100,000 × 1.10^10) | Real ≈ ₹144,800 (259,374 ÷ 1.06^10) |
Practical implications
- Holding cash over long periods erodes wealth—you lose purchasing power even if nominal amount stays unchanged.
- Choose investments that can generate real returns (returns above inflation): equities, inflation-linked bonds, some real assets.
- Compare fixed-income offers on a real (after-inflation) basis, not just nominal yield.
- Factor taxes into real returns — after-tax real return = (1 + r_nominal × (1 − tax_rate)) ÷ (1 + g) − 1 (approximation).
Ways to protect your savings from inflation
- Equity mutual funds / direct equities: Historically higher real returns over long horizons (higher volatility though).
- Index-linked bonds / inflation-indexed bonds: Provide returns linked to inflation (protect purchasing power).
- Real assets: Real estate, gold — can act as partial hedge (consider liquidity, costs, and diversification).
- Diversify & review: Use a mix of asset classes and review allocations as goals and horizons change.
Try our Inflation Calculator
Quickly test scenarios — future cost of a goal, required savings to beat inflation, and real return calculations:
Frequently asked questions
Q: Is nominal return − inflation always a good approximation for real return?
A: It’s a quick approximation when rates are small. The exact real return is (1 + r_nominal)/(1 + g) − 1. For higher rates the difference becomes material.
Q: How should I choose an inflation assumption for planning?
A: Use a range: conservative (6%–7%), base (4%–6%), and optimistic (3%–4%). For education/healthcare, use slightly higher estimates because these categories often rise faster than headline CPI.
Q: Should I aim for a fixed real return target?
A: Yes — aim for investments that can plausibly deliver returns above inflation for your horizon. For long-term goals, plan for a real return target (e.g., 3% real) rather than a nominal target only.
Disclaimer: Examples use rounded numbers and assumed constant rates for clarity. Actual inflation and investment returns vary. Use the Inflation Calculator for personalised projections and consult a financial advisor for tailored planning.