Short answer — several Indian investing apps include very good SIP calculators. Top choices:

• Groww — simple, accurate SIP and step‑up calculators built into the app/site; good for quick goal estimates and investing directly. (groww.in)
• Zerodha Coin — full-featured SIP and step‑up calculators on Coin (web + app) with goal/SWP/step‑up options. (zerodha.com)
• ET Money — SIP and Step‑Up SIP calculators plus fund suggestions and goal planning tools. (etmoney.com)
• Kuvera — strong goal‑based planning and SIP/goal calculators (designed for goal planning and family accounts). (apps.apple.com)
• Paytm Money — SIP calculator available across Android/iOS and web, with equity/mutual‑fund options. (paytmmoney.com)

Quick note: SIP calculators give estimates (they usually don’t include expense ratios, exit loads or actual market performance) — use them to plan, then check fund details before investing. (groww.in)

If you want, I can show which app’s calculator best fits a specific goal (retirement, child education, target corpus) or walk through an example calculation.