Total monthly subscriptions cost calculator

What to send: subscriptions, fees, and billing plans

Send a JSON body with a required subscriptions array—aliases items, list, services, and plans are accepted when your client already uses another field name. Fee may arrive as a number or a numeric string; aliases amount, price, cost, and charge map to the same value so billing exports and form builders can keep familiar keys. Negative fees raise invalid_input with a message that the fee cannot be negative—the product promise for this calculator is a recurring monthly cost total, not a refund ledger. Extremely large fees and very long lists are capped so Worker isolate math stays bounded.

How monthly equivalents and the total are computed

For every subscription the engine multiplies the billed fee by how many times that plan occurs in one year, then divides by twelve to produce a monthly equivalent: weekly uses fifty-two periods, biweekly uses twenty-six, monthly uses twelve, quarterly uses four, semiannual uses two, and yearly uses one. That means a yearly plan of one hundred nineteen point eighty-eight becomes nine point ninety-nine per month, while a monthly fee of fifteen point ninety-nine stays fifteen point ninety-nine. Intermediate products use ordinary floating-point arithmetic; every money field in the response is then rounded half-up to two decimal places so results look like currency on a statement rather than long binary fractions. Each result line includes its zero-based index, display name, echoed fee, canonical plan label, monthly_cost, and share_pct of the grand monthly total. Top-level total_monthly sums the pre-rounded monthly contributions so the grand total stays consistent with the line math before final half-up rounding. yearly_projection multiplies the same pre-rounded monthly sum by twelve for an annualized view without changing the monthly-first product promise. The count field equals the number of input rows, currency_decimals is always two, and method is always monthly_subscriptions_total so downstream code can branch without sniffing shapes. Missing subscriptions, empty lists, missing fee, missing plan, non-numeric fees, unknown plans, and negative fees all fail with invalid_input and are not charged after rejection. Identical inputs always produce identical JSON because the path is pure arithmetic with no network, no random seed, and no wall clock.

API usage, pricing, budget workflows, and practical limits

Call the free in-browser total monthly subscriptions cost calculator when you are auditing a personal stack, deciding which yearly plan to cancel first, or teaching household budgeting without building a spreadsheet of period factors. Keep lists within ordinary household or team sizes; the published subscription cap protects isolate runtime while still covering full media and software stacks. The product promise is transparent plan normalization and summed monthly recurring spend, not live merchant scraping or bank-feed classification—those intents belong to different tools with different search terms and engines. Use the prepaid API when a personal-finance app, expense coach, SaaS procurement helper, family shared-cost bot, or onboarding flow needs a stable KIT contract at $0.002 per successful item; validation failures never consume balance after the engine rejects the request. Pair this endpoint with currency converters only when every fee already shares one currency—this capability does not convert foreign exchange, apply sales tax, trial credits, or promo codes. Authors shipping SDKs can map the lines array into comparison tables and surface total_monthly in a summary banner for cancel-or-keep decisions, using share_pct to highlight the largest monthly drag.