{"tool":{"slug":"compound-interest","name":"Compound interest calculator","version":"2026-08-21","canonicalUrl":"https://carlo.finance/tools/compound-interest?principal=115000","jsonUrl":"https://carlo.finance/tools/compound-interest.json?principal=115000","pageUrl":"https://carlo.finance/tools/compound-interest","parameters":[{"key":"principal","label":"Starting amount","unit":"usd","min":0,"max":100000000,"default":10000,"sourceId":null,"help":"What you start with. The default is an example, not a statistic."},{"key":"monthly","label":"Monthly contribution","unit":"usd-per-month","min":0,"max":1000000,"default":250,"sourceId":null,"help":"Added at the end of each month. The default is an example; set it to zero to grow the starting amount alone."},{"key":"rate","label":"Annual return","unit":"percent","min":0,"max":20,"default":7,"sourceId":null,"help":"The yearly growth you assume, before taxes and fees. This is an assumption you choose, not a forecast; the default is an example to replace with your own."},{"key":"years","label":"Years to grow","unit":"years","min":1,"max":60,"default":20,"sourceId":null,"integer":true,"help":"How long the money compounds before you look at the balance."},{"key":"compounds","label":"Compounding per year","unit":"count","min":1,"max":365,"default":12,"sourceId":null,"integer":true,"help":"How many times a year interest is credited: 1 yearly, 12 monthly, 365 daily."}]},"inputs":{"principal":115000,"monthly":250,"rate":7,"years":20,"compounds":12},"result":{"endBalance":594686.63,"totalContributed":175000,"growth":419686.63,"effectiveAnnualYield":7.229,"doublingYears":9.931,"months":240,"finalYearGrowth":39980.99,"yearly":[{"year":1,"contributed":118000,"growth":8411.51,"balance":126411.51},{"year":2,"contributed":121000,"growth":17647.95,"balance":138647.95},{"year":3,"contributed":124000,"growth":27768.97,"balance":151768.97},{"year":4,"contributed":127000,"growth":38838.51,"balance":165838.51},{"year":5,"contributed":130000,"growth":50925.13,"balance":180925.13},{"year":6,"contributed":133000,"growth":64102.37,"balance":197102.37},{"year":7,"contributed":136000,"growth":78449.06,"balance":214449.06},{"year":8,"contributed":139000,"growth":94049.75,"balance":233049.75},{"year":9,"contributed":142000,"growth":110995.08,"balance":252995.08},{"year":10,"contributed":145000,"growth":129382.26,"balance":274382.26},{"year":11,"contributed":148000,"growth":149315.52,"balance":297315.52},{"year":12,"contributed":151000,"growth":170906.63,"balance":321906.63},{"year":13,"contributed":154000,"growth":194275.43,"balance":348275.43},{"year":14,"contributed":157000,"growth":219550.44,"balance":376550.44},{"year":15,"contributed":160000,"growth":246869.45,"balance":406869.45},{"year":16,"contributed":163000,"growth":276380.22,"balance":439380.22},{"year":17,"contributed":166000,"growth":308241.2,"balance":474241.2},{"year":18,"contributed":169000,"growth":342622.28,"balance":511622.28},{"year":19,"contributed":172000,"growth":379705.64,"balance":551705.64},{"year":20,"contributed":175000,"growth":419686.63,"balance":594686.63}]},"drivers":[{"key":"years","label":"Years to grow","step":5,"endDelta":266254.39,"sentence":"Each 5 more years of compounding adds $266,254 to the final balance."},{"key":"rate","label":"Annual return","step":1,"endDelta":119150.79000000004,"sentence":"Each point of assumed return adds $119,151 to the final balance."},{"key":"monthly","label":"Monthly contribution","step":100,"endDelta":52092.67000000004,"sentence":"Each $100 more a month adds $52,093 to the final balance."},{"key":"principal","label":"Starting amount","step":1000,"endDelta":4038.7399999999907,"sentence":"Each $1,000 more at the start adds $4,039 to the final balance."}],"sensitivity":{"byRate":[{"rate":4,"endBalance":347290.6,"growth":172290.6},{"rate":5,"endBalance":414712.05,"growth":239712.05},{"rate":6,"endBalance":496183.74,"growth":321183.74},{"rate":7,"endBalance":594686.63,"growth":419686.63},{"rate":8,"endBalance":713837.42,"growth":538837.42},{"rate":10,"endBalance":1032570.68,"growth":857570.68}],"byYears":[{"years":5,"endBalance":180925.13,"contributed":130000,"growth":50925.13},{"years":10,"endBalance":274382.26,"contributed":145000,"growth":129382.26},{"years":20,"endBalance":594686.63,"contributed":175000,"growth":419686.63},{"years":30,"endBalance":1238389.96,"contributed":205000,"growth":1033389.96},{"years":40,"endBalance":2532015.67,"contributed":235000,"growth":2297015.67}]},"assumptions":[{"key":"principal","label":"Starting amount","value":115000,"unit":"usd","provided":true,"source":null},{"key":"monthly","label":"Monthly contribution","value":250,"unit":"usd-per-month","provided":false,"source":null},{"key":"rate","label":"Annual return","value":7,"unit":"percent","provided":false,"source":null},{"key":"years","label":"Years to grow","value":20,"unit":"years","provided":false,"source":null},{"key":"compounds","label":"Compounding per year","value":12,"unit":"count","provided":false,"source":null}],"sources":[],"warnings":[],"disclaimer":"This models deterministic compound growth at a rate you choose. It is not a forecast, a promised return, or investment advice. Real returns vary year to year and can be negative; taxes, fees, and inflation sit outside the model."}