Finance Toolkit › Free calculators

Compound Interest Calculator with Monthly Contributions

Project savings growth with monthly compounding, recurring contributions, and an optional annual contribution increase.

The same calculation as an API

Building something? This page calls the same deterministic math the Finance Toolkit API exposes as JSON. Free tier, no signup, no key:

curl -s https://smeltworks.com/financetoolkit/v1/savings/compound \
  -H 'content-type: application/json' \
  -d '{"initial":1000,"monthly_contribution":200,"annual_return":7,"years":10}'

See all endpoints and pricing →

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