{"success":true,"version":"v1","request":{"tool":"get_calculator_schema","calculator_id":"savings-goal"},"result":{"entity_type":"calculator","id":"savings-goal","calculator_id":"savings-goal","canonical_url":"https://tttkmbb.com/finance/savings-goal","name":"Savings Goal Calculator","title":"Savings Goal Calculator – Monthly Deposit Needed to Reach a Target Amount","category":"finance","category_name":"Finance","tool_name":"calculate_savings_goal_deposit","featured_mcp_tool":false,"description":"Solves for the fixed end-of-month deposit required to grow current savings to a goal amount within a given number of years at a monthly-compounded annual rate.","use_when":"You know the target amount, the deadline and an expected return and want the monthly saving required (emergency fund, down payment, tuition).","do_not_use_when":"You already know the deposit and want the resulting balance (use compound-interest or future-value), or the contributions are irregular.","inputs":[{"name":"goal_amount","label":"Goal amount","type":"number","required":true,"max":1000000000000,"exclusive_min":0,"description":"Target balance to reach.","example":50000},{"name":"current_savings","label":"Current savings","type":"number","required":false,"default":0,"min":0,"max":1000000000000,"description":"Amount already saved; it keeps compounding at the same rate.","example":0},{"name":"years","label":"Time to goal","type":"number","unit":"years","required":true,"max":100,"exclusive_min":0,"description":"Years until the goal is needed; rounded to whole months.","example":10},{"name":"annual_rate_percent","label":"Annual return","type":"number","unit":"%","required":false,"default":0,"min":0,"max":100,"description":"Expected annual interest or return in percent, compounded monthly. Use 0 for cash under the mattress.","example":5}],"outputs":[{"name":"monthly_deposit","label":"Monthly deposit required","type":"number","decimals":2,"description":"End-of-month deposit that reaches the goal exactly."},{"name":"months","label":"Number of deposits","type":"integer","decimals":0,"description":"12 × years, rounded."},{"name":"total_deposits","label":"Total deposited","type":"number","decimals":2,"description":"monthly_deposit × months."},{"name":"future_value_of_current_savings","label":"Current savings at goal date","type":"number","decimals":2,"description":"current_savings × (1 + i)^months."},{"name":"interest_earned","label":"Interest earned","type":"number","decimals":2,"description":"goal_amount − current_savings − total_deposits."}],"input_schema":{"type":"object","properties":{"goal_amount":{"description":"Target balance to reach.","type":"number","maximum":1000000000000,"exclusiveMinimum":0,"examples":[50000]},"current_savings":{"description":"Amount already saved; it keeps compounding at the same rate.","type":"number","minimum":0,"maximum":1000000000000,"default":0,"examples":[0]},"years":{"description":"Years until the goal is needed; rounded to whole months. Unit: years.","type":"number","maximum":100,"exclusiveMinimum":0,"examples":[10],"x-unit":"years"},"annual_rate_percent":{"description":"Expected annual interest or return in percent, compounded monthly. Use 0 for cash under the mattress. Unit: %.","type":"number","minimum":0,"maximum":100,"default":0,"examples":[5],"x-unit":"%"}},"additionalProperties":false,"required":["goal_amount","years"]},"output_schema":{"type":"object","properties":{"monthly_deposit":{"description":"End-of-month deposit that reaches the goal exactly.","type":"number"},"months":{"description":"12 × years, rounded.","type":"integer"},"total_deposits":{"description":"monthly_deposit × months.","type":"number"},"future_value_of_current_savings":{"description":"current_savings × (1 + i)^months.","type":"number"},"interest_earned":{"description":"goal_amount − current_savings − total_deposits.","type":"number"}}},"formula":"i = annual_rate_percent / 1200; m = 12·years; FV_current = current_savings × (1 + i)^m; monthly_deposit = (goal_amount − FV_current) × i / ((1 + i)^m − 1); if i = 0, monthly_deposit = (goal_amount − FV_current) / m","method":"Ordinary-annuity (end-of-month) sinking-fund formula with monthly compounding; returns are assumed constant and taxes and fees are ignored.","sources":[{"name":"Wikipedia – Time value of money","url":"https://en.wikipedia.org/wiki/Time_value_of_money","type":"reference","retrieved_at":"2026-09-23"},{"name":"Investopedia – Compound Interest: Formula and Examples","url":"https://www.investopedia.com/terms/c/compoundinterest.asp","type":"reference","retrieved_at":"2026-09-23"}],"freshness":{"type":"static","max_age_seconds":null,"note":"Deterministic formula with fixed constants; results never go stale. Inputs supplied by the caller determine the output."},"examples":[{"name":"50,000 in 10 years at 5 %","inputs":{"goal_amount":50000,"years":10,"annual_rate_percent":5},"expected":{"monthly_deposit":321.99,"months":120,"total_deposits":38639.31,"interest_earned":11360.69},"url":"https://tttkmbb.com/api/v1/calculate/savings-goal?goal_amount=50000&years=10&annual_rate_percent=5"},{"name":"20,000 in 3 years starting from 5,000 at 4 %","inputs":{"goal_amount":20000,"current_savings":5000,"years":3,"annual_rate_percent":4},"expected":{"monthly_deposit":376.19,"months":36,"future_value_of_current_savings":5636.36},"url":"https://tttkmbb.com/api/v1/calculate/savings-goal?goal_amount=20000&current_savings=5000&years=3&annual_rate_percent=4"}],"faq":[{"q":"What if my current savings already cover the goal?","a":"monthly_deposit is reported as 0 and a note says the existing balance reaches the goal on its own at that rate."},{"q":"Should I use a nominal or real return?","a":"Use a nominal return if the goal is a fixed nominal sum; use a real (inflation-adjusted) return if the goal is in today's purchasing power (see inflation)."}],"tags":["savings goal","how much to save per month","sinking fund","monthly deposit","target amount"],"related":[{"calculator_id":"compound-interest","reason":"Project the balance for a chosen deposit instead."},{"calculator_id":"inflation","reason":"Convert a goal in today's money to its future nominal cost."}],"links":{"html":"https://tttkmbb.com/finance/savings-goal","markdown":"https://tttkmbb.com/finance/savings-goal.md","json":"https://tttkmbb.com/finance/savings-goal.json","api":"https://tttkmbb.com/api/v1/calculate/savings-goal","schema":"https://tttkmbb.com/api/v1/calculators/savings-goal","openapi":"https://tttkmbb.com/openapi.json","mcp":"https://tttkmbb.com/mcp"},"version":"v1","updated_at":"2026-09-23"},"timestamp":"2026-09-23T23:31:58Z"}