Compound Savings Calculator
Model an initial deposit plus equal periodic contributions. Compare beginning/end contributions, nominal/effective annual rates, total deposits and before-tax growth.
YOUR CALCULATION
Result
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Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Convert the entered annual rate into a per-period rate. Grow the initial deposit for all periods and add the geometric series of equal contributions. Beginning-period contributions receive one extra period of growth compared with end-period contributions.
FV=P(1+r)^N+C[(1+r)^N−1]/r; beginning-period contributions multiply theC term by(1+r)
Worked example
With1000 initially,100 contributed at the end of every year,5% annual rate and2 years, the balance is1307.50. Deposits total1200 and modeled interest107.50. Beginning-year contributions instead give1317.75.
Assumptions and input details
Use one entered currency; no exchange rate is applied. Deposits are nonnegative and limited to1e12. Annual rate is an entered constant from−99% to100%, not a market quote or guaranteed return. Years are integers0–100. Contribution and compounding frequency are the same. Zero rate gives principal plus contributions exactly in this model. Results are before tax: tax treatment is unspecified and fees, inflation and variable returns are not modeled. Annual chart points are samples rather than a continuous account path.
References: Investor.gov compound-interest inputs · OpenStax annuities and timing
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
Apply an entered constant growth or decay rate to an initial quantity. Compare periodic and continuous models, view a time curve and find doubling time or half-life.
Find the nth term and sum of an arithmetic or geometric sequence. Inspect terms, running totals, a term graph and a convergent geometric sum where applicable.
Find a percentage of a value, percentage change, or the percentage represented by a part. See substituted numbers, steps and a number line.
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