{"success":true,"version":"v1","request":{"tool":"get_calculator_schema","calculator_id":"down-payment"},"result":{"entity_type":"calculator","id":"down-payment","calculator_id":"down-payment","canonical_url":"https://tttkmbb.com/finance/down-payment","name":"Down Payment Calculator","title":"Down Payment Calculator – Loan Amount, Loan-to-Value Ratio and Estimated PMI","category":"finance","category_name":"Finance","tool_name":"calculate_down_payment","featured_mcp_tool":false,"description":"Converts a down payment given as an amount or a percentage of the home price into the loan amount and loan-to-value ratio, flags whether private mortgage insurance is likely (LTV above 80 %) and estimates its annual and monthly cost at a given PMI rate.","use_when":"You want to know how much you will borrow and whether PMI applies for a given home price and down payment, or how much more cash reaches 20 % down.","do_not_use_when":"You need the monthly mortgage payment (use mortgage-payment) or a savings plan to reach the down payment (use savings-goal).","inputs":[{"name":"home_price","label":"Home price","type":"number","required":true,"max":10000000000,"exclusive_min":0,"description":"Purchase price of the home.","example":350000},{"name":"down_payment_amount","label":"Down payment (amount)","type":"number","required":false,"min":0,"max":10000000000,"description":"Down payment in currency; takes precedence over down_payment_percent when both are given.","example":35000},{"name":"down_payment_percent","label":"Down payment (percent)","type":"number","unit":"%","required":false,"min":0,"max":100,"description":"Down payment as a percent of home_price (used when down_payment_amount is omitted).","example":10},{"name":"pmi_rate_percent","label":"PMI rate","type":"number","unit":"% of loan/year","required":false,"default":0.75,"min":0,"max":5,"description":"Annual private mortgage insurance premium as a percent of the loan amount; typical range 0.3–1.5 % depending on credit score and LTV.","example":0.75}],"outputs":[{"name":"down_payment","label":"Down payment","type":"number","decimals":2,"description":"Down payment in currency."},{"name":"down_payment_percent","label":"Down payment","type":"number","unit":"%","decimals":2,"description":"down_payment / home_price × 100."},{"name":"loan_amount","label":"Loan amount","type":"number","decimals":2,"description":"home_price − down_payment."},{"name":"loan_to_value_percent","label":"Loan-to-value (LTV)","type":"number","unit":"%","decimals":2,"description":"loan_amount / home_price × 100."},{"name":"pmi_likely","label":"PMI likely","type":"boolean","decimals":4,"description":"True when LTV exceeds 80 % (conventional loans usually require PMI)."},{"name":"estimated_annual_pmi","label":"Estimated PMI per year","type":"number","decimals":2,"description":"loan_amount × pmi_rate_percent / 100 when PMI is likely, otherwise 0."},{"name":"estimated_monthly_pmi","label":"Estimated PMI per month","type":"number","decimals":2,"description":"estimated_annual_pmi / 12."},{"name":"down_payment_for_20_percent","label":"Down payment for 20 %","type":"number","decimals":2,"description":"0.2 × home_price, the amount that avoids PMI on conventional loans."},{"name":"additional_needed_for_20_percent","label":"Additional cash to reach 20 %","type":"number","decimals":2,"description":"max(0, down_payment_for_20_percent − down_payment)."},{"name":"assessment","label":"Assessment","type":"string","decimals":4,"description":"Plain-language note on the LTV and PMI status."}],"input_schema":{"type":"object","properties":{"home_price":{"description":"Purchase price of the home.","type":"number","maximum":10000000000,"exclusiveMinimum":0,"examples":[350000]},"down_payment_amount":{"description":"Down payment in currency; takes precedence over down_payment_percent when both are given.","type":"number","minimum":0,"maximum":10000000000,"examples":[35000]},"down_payment_percent":{"description":"Down payment as a percent of home_price (used when down_payment_amount is omitted). Unit: %.","type":"number","minimum":0,"maximum":100,"examples":[10],"x-unit":"%"},"pmi_rate_percent":{"description":"Annual private mortgage insurance premium as a percent of the loan amount; typical range 0.3–1.5 % depending on credit score and LTV. Unit: % of loan/year.","type":"number","minimum":0,"maximum":5,"default":0.75,"examples":[0.75],"x-unit":"% of loan/year"}},"additionalProperties":false,"required":["home_price"]},"output_schema":{"type":"object","properties":{"down_payment":{"description":"Down payment in currency.","type":"number"},"down_payment_percent":{"description":"down_payment / home_price × 100. Unit: %.","type":"number","x-unit":"%"},"loan_amount":{"description":"home_price − down_payment.","type":"number"},"loan_to_value_percent":{"description":"loan_amount / home_price × 100. Unit: %.","type":"number","x-unit":"%"},"pmi_likely":{"description":"True when LTV exceeds 80 % (conventional loans usually require PMI).","type":"boolean"},"estimated_annual_pmi":{"description":"loan_amount × pmi_rate_percent / 100 when PMI is likely, otherwise 0.","type":"number"},"estimated_monthly_pmi":{"description":"estimated_annual_pmi / 12.","type":"number"},"down_payment_for_20_percent":{"description":"0.2 × home_price, the amount that avoids PMI on conventional loans.","type":"number"},"additional_needed_for_20_percent":{"description":"max(0, down_payment_for_20_percent − down_payment).","type":"number"},"assessment":{"description":"Plain-language note on the LTV and PMI status.","type":"string"}}},"formula":"down_payment = down_payment_amount or home_price × down_payment_percent/100; loan_amount = home_price − down_payment; LTV = loan_amount / home_price × 100; PMI likely if LTV > 80; annual_pmi = loan_amount × pmi_rate_percent/100","method":"The 80 % LTV threshold applies to conventional (Fannie Mae/Freddie Mac) loans; FHA loans charge mortgage insurance at any LTV and VA loans charge none. PMI rates vary with credit score, LTV and loan type, so the estimate is indicative only.","sources":[{"name":"CFPB – What is private mortgage insurance?","url":"https://www.consumerfinance.gov/ask-cfpb/what-is-private-mortgage-insurance-en-122/","type":"government","retrieved_at":"2026-09-24"},{"name":"Wikipedia – Loan-to-value ratio","url":"https://en.wikipedia.org/wiki/Loan-to-value_ratio","type":"reference","retrieved_at":"2026-09-24"},{"name":"CFPB – Owning a Home: loan costs and monthly payment components","url":"https://www.consumerfinance.gov/owning-a-home/","type":"government","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":"350,000 home, 10 % down","inputs":{"home_price":350000,"down_payment_percent":10},"expected":{"down_payment":35000,"down_payment_percent":10,"loan_amount":315000,"loan_to_value_percent":90,"pmi_likely":true,"estimated_annual_pmi":2362.5,"estimated_monthly_pmi":196.88,"down_payment_for_20_percent":70000,"additional_needed_for_20_percent":35000},"url":"https://tttkmbb.com/api/v1/calculate/down-payment?home_price=350000&down_payment_percent=10"},{"name":"500,000 home, 100,000 down","inputs":{"home_price":500000,"down_payment_amount":100000},"expected":{"down_payment":100000,"down_payment_percent":20,"loan_amount":400000,"loan_to_value_percent":80,"pmi_likely":false,"estimated_annual_pmi":0,"additional_needed_for_20_percent":0},"url":"https://tttkmbb.com/api/v1/calculate/down-payment?home_price=500000&down_payment_amount=100000"}],"faq":[{"q":"When does PMI stop?","a":"Under the US Homeowners Protection Act you can request cancellation at 80 % LTV based on the original value, and the lender must cancel automatically at 78 % if payments are current."},{"q":"Is exactly 20 % down enough to avoid PMI?","a":"Yes: PMI is required when LTV is above 80 %, so a 20 % down payment (LTV = 80 %) avoids it on conventional loans."}],"tags":["down payment","loan to value","ltv","pmi calculator","20 percent down","mortgage insurance"],"related":[{"calculator_id":"mortgage-payment","reason":"Monthly payment on the resulting loan amount."},{"calculator_id":"savings-goal","reason":"Monthly saving needed to reach the down payment."},{"calculator_id":"debt-to-income","reason":"Check whether the payment fits lender DTI limits."}],"links":{"html":"https://tttkmbb.com/finance/down-payment","markdown":"https://tttkmbb.com/finance/down-payment.md","json":"https://tttkmbb.com/finance/down-payment.json","api":"https://tttkmbb.com/api/v1/calculate/down-payment","schema":"https://tttkmbb.com/api/v1/calculators/down-payment","openapi":"https://tttkmbb.com/openapi.json","mcp":"https://tttkmbb.com/mcp"},"version":"v1","updated_at":"2026-09-24"},"timestamp":"2026-09-24T01:57:48Z"}