{"success":true,"version":"v1","request":{"tool":"get_calculator_schema","calculator_id":"student-loan"},"result":{"entity_type":"calculator","id":"student-loan","calculator_id":"student-loan","canonical_url":"https://tttkmbb.com/finance/student-loan","name":"Student Loan Calculator","title":"Student Loan Repayment Calculator – Standard and Graduated Plans with Grace-Period Interest","category":"finance","category_name":"Finance","tool_name":"calculate_student_loan_payment","featured_mcp_tool":false,"description":"Computes the monthly payment and total interest of a student loan under a standard (level) plan or an approximation of the US federal graduated plan, including interest that accrues during a grace period and is capitalized when repayment starts.","use_when":"You want the monthly payment, total cost or effect of a grace period for a fixed-rate student loan under standard or graduated repayment.","do_not_use_when":"The loan is income-driven (IBR, PAYE, SAVE), variable-rate, or you know the payment and want the payoff time (use debt-payoff).","inputs":[{"name":"balance","label":"Loan balance","type":"number","required":true,"max":100000000,"exclusive_min":0,"description":"Principal owed when the grace period starts (or today if repayment has begun).","example":30000},{"name":"annual_rate_percent","label":"Interest rate","type":"number","unit":"%","required":true,"min":0,"max":100,"description":"Fixed annual rate in percent.","example":6},{"name":"term_years","label":"Repayment term","type":"number","unit":"years","required":false,"default":10,"max":30,"exclusive_min":0,"description":"Length of repayment in years (10 for federal Standard and Graduated plans; up to 25–30 for extended plans).","example":10},{"name":"grace_months","label":"Grace period","type":"integer","unit":"months","required":false,"default":0,"min":0,"max":36,"description":"Months before the first payment (6 for federal Direct loans).","example":0},{"name":"interest_accrues_during_grace","label":"Interest accrues during grace","type":"boolean","required":false,"default":true,"description":"True for unsubsidized loans (interest accrues and is capitalized); false for subsidized loans, where the government pays grace-period interest.","example":true},{"name":"repayment_plan","label":"Repayment plan","type":"enum","required":false,"default":"standard","values":[{"value":"standard","label":"Standard (level payments)","aliases":["level","fixed"]},{"value":"graduated","label":"Graduated (payments rise every 2 years)","aliases":["step","increasing"]}],"description":"Standard: equal monthly payments. Graduated: payments step up every 24 months, the last step no more than 3× the first.","example":"standard"}],"outputs":[{"name":"balance_at_repayment_start","label":"Balance when repayment starts","type":"number","decimals":2,"description":"balance + capitalized_interest."},{"name":"capitalized_interest","label":"Capitalized grace interest","type":"number","decimals":2,"description":"balance × rate/12 × grace_months (simple interest), added to principal when repayment starts."},{"name":"number_of_payments","label":"Number of payments","type":"integer","decimals":0,"description":"12 × term_years."},{"name":"monthly_payment","label":"Monthly payment (first)","type":"number","decimals":2,"description":"Level payment (standard) or the first-step payment (graduated)."},{"name":"final_monthly_payment","label":"Monthly payment (last)","type":"number","decimals":2,"description":"Payment in the final step (same as monthly_payment for standard)."},{"name":"total_paid","label":"Total paid","type":"number","decimals":2,"description":"Sum of all payments."},{"name":"total_interest","label":"Total interest","type":"number","decimals":2,"description":"total_paid − balance (includes capitalized grace interest)."},{"name":"payment_steps","label":"Payment steps","type":"list","decimals":2,"description":"Rows of from_month, to_month and payment for each step (one row for standard)."}],"input_schema":{"type":"object","properties":{"balance":{"description":"Principal owed when the grace period starts (or today if repayment has begun).","type":"number","maximum":100000000,"exclusiveMinimum":0,"examples":[30000]},"annual_rate_percent":{"description":"Fixed annual rate in percent. Unit: %.","type":"number","minimum":0,"maximum":100,"examples":[6],"x-unit":"%"},"term_years":{"description":"Length of repayment in years (10 for federal Standard and Graduated plans; up to 25–30 for extended plans). Unit: years.","type":"number","maximum":30,"exclusiveMinimum":0,"default":10,"examples":[10],"x-unit":"years"},"grace_months":{"description":"Months before the first payment (6 for federal Direct loans). Unit: months.","type":"integer","minimum":0,"maximum":36,"default":0,"examples":[0],"x-unit":"months"},"interest_accrues_during_grace":{"description":"True for unsubsidized loans (interest accrues and is capitalized); false for subsidized loans, where the government pays grace-period interest.","type":"boolean","default":true,"examples":[true]},"repayment_plan":{"description":"Standard: equal monthly payments. Graduated: payments step up every 24 months, the last step no more than 3× the first.","type":"string","enum":["standard","graduated"],"default":"standard","examples":["standard"]}},"additionalProperties":false,"required":["balance","annual_rate_percent"]},"output_schema":{"type":"object","properties":{"balance_at_repayment_start":{"description":"balance + capitalized_interest.","type":"number"},"capitalized_interest":{"description":"balance × rate/12 × grace_months (simple interest), added to principal when repayment starts.","type":"number"},"number_of_payments":{"description":"12 × term_years.","type":"integer"},"monthly_payment":{"description":"Level payment (standard) or the first-step payment (graduated).","type":"number"},"final_monthly_payment":{"description":"Payment in the final step (same as monthly_payment for standard).","type":"number"},"total_paid":{"description":"Sum of all payments.","type":"number"},"total_interest":{"description":"total_paid − balance (includes capitalized grace interest).","type":"number"},"payment_steps":{"description":"Rows of from_month, to_month and payment for each step (one row for standard).","type":"array"}}},"formula":"capitalized_interest = balance × annual_rate_percent/1200 × grace_months (if accruing); B = balance + capitalized_interest; i = annual_rate_percent/1200; n = 12·term_years. Standard: payment = B × i / (1 − (1 + i)^−n). Graduated: k = ceil(n/24) steps, step ratio g = 3^(1/(k−1)), first payment P solves Σ_s P·g^s × (1 − (1+i)^−m_s)/i × (1+i)^(−24s) = B, with P raised to at least B × i (interest-only) and g reduced accordingly.","method":"Federal Standard plan arithmetic is exact. The Graduated plan is an approximation of the federal rule (payments rise every two years, first payment at least the monthly interest, last payment at most three times the first); servicers set the actual steps. Capitalization follows federal Direct Loan practice for unsubsidized loans.","sources":[{"name":"Federal Student Aid – Repayment plans (Standard and Graduated)","url":"https://studentaid.gov/manage-loans/repayment/plans","type":"government","retrieved_at":"2026-09-24"},{"name":"Federal Student Aid – Interest rates and how interest is calculated and capitalized","url":"https://studentaid.gov/understand-aid/types/loans/interest-rates","type":"government","retrieved_at":"2026-09-24"},{"name":"Wikipedia – Amortization calculator (annuity payment formula)","url":"https://en.wikipedia.org/wiki/Amortization_calculator","type":"reference","retrieved_at":"2026-09-24"}],"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":"30,000 at 6 % over 10 years, standard","inputs":{"balance":30000,"annual_rate_percent":6,"term_years":10},"expected":{"balance_at_repayment_start":30000,"capitalized_interest":0,"number_of_payments":120,"monthly_payment":333.06,"final_monthly_payment":333.06,"total_paid":39967.38,"total_interest":9967.38},"url":"https://tttkmbb.com/api/v1/calculate/student-loan?balance=30000&annual_rate_percent=6&term_years=10"},{"name":"30,000 at 6 %, 6-month grace, graduated over 10 years","inputs":{"balance":30000,"annual_rate_percent":6,"term_years":10,"grace_months":6,"repayment_plan":"graduated"},"expected":{"balance_at_repayment_start":30900,"capitalized_interest":900,"monthly_payment":196.17,"final_monthly_payment":588.51,"total_paid":43915.06,"total_interest":13915.06},"url":"https://tttkmbb.com/api/v1/calculate/student-loan?balance=30000&annual_rate_percent=6&term_years=10&grace_months=6&repayment_plan=graduated"}],"faq":[{"q":"Why does the graduated plan cost more?","a":"Lower early payments leave more principal outstanding for longer, so more interest accrues; on 30,900 at 6 % the graduated plan costs about 3,900 more than the standard plan over 10 years."},{"q":"How much does a grace period cost?","a":"For an unsubsidized loan, interest accrues at the simple rate and is capitalized: 30,000 at 6 % accrues 900 in six months, and interest is then charged on 30,900."}],"tags":["student loan","student loan payment","graduated repayment","standard repayment","grace period interest","capitalized interest"],"related":[{"calculator_id":"loan-payment","reason":"Level payment on any amortizing loan."},{"calculator_id":"amortization-schedule","reason":"Year-by-year balance of the standard plan."},{"calculator_id":"debt-payoff","reason":"Payoff time for a chosen payment."}],"links":{"html":"https://tttkmbb.com/finance/student-loan","markdown":"https://tttkmbb.com/finance/student-loan.md","json":"https://tttkmbb.com/finance/student-loan.json","api":"https://tttkmbb.com/api/v1/calculate/student-loan","schema":"https://tttkmbb.com/api/v1/calculators/student-loan","openapi":"https://tttkmbb.com/openapi.json","mcp":"https://tttkmbb.com/mcp"},"version":"v1","updated_at":"2026-09-24"},"timestamp":"2026-09-24T01:49:42Z","next_actions":[{"tool":"run_calculator","calculator_id":"student-loan","reason":"Run Student Loan Calculator with the inputs above."}],"links":{"markdown":"https://tttkmbb.com/finance/student-loan.md"}}