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SIP Calculator

Enter the amount per period, investment horizon and expected annual return, choose weekly, monthly, quarterly, semi-annual or annual investing, and see the ending balance, total contributions, gains and yearly breakdown.

Saving a fixed amount every month is deliberately boring, and for the first few years the balance barely seems to move — money goes in and the account looks the same. The year-by-year breakdown here shows what was paid in, what was earned, and the year the curve finally starts to bend. Returns are assumed constant, so treat the figures as an ideal path rather than a forecast.

The constant-return assumption is the whole caveat: real markets move, and what a regular saver actually ends up with depends on the price at the point of sale — the "smile curve" describes the lucky case, not a guarantee. Each contribution is credited at the end of its period, so it earns nothing in the period it is paid, and the annual rate is converted per period by compounding rather than by dividing: a monthly rate of (1 + annual)^(1/12) − 1, which is slightly lower than simply dividing by twelve.

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How to use

  1. Enter the amount contributed each period, the number of years and the expected annual return.
  2. Choose the contribution frequency — weekly, monthly, quarterly, half-yearly or yearly.
  3. Read the final balance, the total contributed, the total earnings and the overall return.
  4. Check the year-by-year table to see when compounding starts to overtake the contributions.

How it works

How the SIP final value is computed

SIP final value = period contribution x [(1 + period rate)^periods - 1] / period rate. For 2,000 monthly at 8% annual over 10 years: convert the nominal annual rate to an effective 8.30%, then to a monthly 0.6667%, totaling 120 periods, for about 365,900, of which 240,000 is principal and 125,900 returns.

Why early years show little return

Each early contribution has a longer compounding period, while later ones have little room to grow, so the SIP curve is "flat then steep." At the same monthly amount, the first year's return is often just a few hundred, accelerating noticeably only by year 5 — which is why SIP often "seems ineffective." It essentially trades time for compounding.

What rate to enter

The rate you enter is a long-term average expected value, not a given year's actual return or a promise. Broad-index funds are often estimated at 6-8% long-term, while equity funds are more volatile. For a conservative view, enter 5% for the floor and 8% for the neutral case — comparing two results beats computing one number.

Code example

JavaScript Future value of regular contributions 

function sip(perPeriod, years, annualRate, periodsPerYear) {
  const r = Math.pow(1 + annualRate, 1 / periodsPerYear) - 1;  // compound conversion
  const n = years * periodsPerYear;
  const fv = perPeriod * ((Math.pow(1 + r, n) - 1) / r);       // ordinary annuity
  return { fv, invested: perPeriod * n,
           gain: fv - perPeriod * n };
}

sip(1000, 10, 0.08, 12);   // ≈ 183,000 (120,000 invested)

Python The same formulas in Python 

def sip(per_period, years, rate, freq=12):
    r = (1 + rate) ** (1 / freq) - 1     # compound conversion to a per-period rate
    n = years * freq
    fv = per_period * ((1 + r) ** n - 1) / r
    return fv, per_period * n

sip(1000, 10, 0.08)   # (≈183000, 120000)

# Real returns depend on the exit point; this assumes a constant rate

FAQ

How exactly is the SIP return computed?

Each contribution is compounded by the remaining periods from its investment time to the end, then all are summed. This equals period contribution x [(1+i)^n - 1] / i, where i is the period rate and n the total periods. The yearly detail table separates cumulative contributions and cumulative returns.

How much does lump-sum investing differ from monthly SIP?

At the same rate and years, lump-sum funds compound fully from the start, so the final value is always higher. For example 100,000 lump-sum for 10 years at 8% is about 216,000; split into 500 monthly contributions the final value is clearly lower — SIP's advantage is volatility smoothing and cash-flow ease, not a higher final value.

How long before SIP shows results?

At least one full market cycle (usually 3-5 years) before the curve visibly lifts. The first 1-2 years show little difference because principal is small and the compounding base low. For a 10+ year goal, early volatility matters far less than "whether you keep contributing."

What rate should I enter?

A long-term average expectation, not last year's gain. Broad-index funds can reference 6-8%, money and bond funds lower (2-4%), and sector/theme funds are volatile and uncertain. Compute both 5% and 8% and treat the result as a range, not a point forecast.

Why is the early-year return in the detail table almost zero?

Because the accumulated principal is small early on. Year 1 contributes about 24,000 total, generating under 1,000 at 8%; by year 10 the account holds over 200,000 compounding, so that year's return is substantial. It's not a miscalculation but compounding's "second-half push."

Does weekly differ from monthly contributing?

At the same annual rate, higher frequency keeps funds invested longer on average and yields a slightly higher final value (usually within 1%). The real difference is operations and fees: off-exchange fund SIPs usually charge per transaction or by amount, so higher frequency means more transactions and possibly higher actual cost.

Should I stop SIP when it's losing?

Mathematically, a falling net value buys more shares with the same money, so stopping gives up the chance to lower the average cost. SIP's core risk is the asset's fundamentals deteriorating (an overturned sector thesis), not a short-term decline — so judge "whether this asset is still worth holding long-term," not "whether it's currently at a loss."

Is the amount I enter uploaded?

No. SIP calculation is just a series of powers and sums, done entirely in the browser with no data sent to a server; history is written only to local localStorage and clearable anytime.