Calculators and money-honest breakdowns for founders who run the numbers.
Featured interactive tool
Model your own monthly bill across OpenAI, Anthropic, and Google — or price a custom model. No signup.
Featured interactive tool
See your blended processing rate across a real transaction mix — not just 2.9% + 30¢. Average ticket, international cards, ACH, and more. No signup.
57 posts
The 2026 Claude API rate card is the floor. Your output-to-input ratio decides the bill. Here it is as a real 30-day bill across three workloads, plus the three levers that cut it.
Firebase pricing in 2026 is free to start (Spark plan: 50K Firestore reads, 20K writes, and 20K deletes per day, 1 GiB stored), then pay-as-you-go on Blaze at $0.06 per 100K reads, $0.18 per 100K writes, and $0.02 per 100K deletes. A typical 5,000-DAU app costs about $12/month, but there is no hard spending cap, so one unbounded query or a looping Cloud Function can turn a $12 bill into thousands overnight.
MongoDB Atlas pricing in 2026 runs from a free 512 MB M0 cluster, to a usage-based Flex tier capped at $30/month, to dedicated clusters that start at $0.08/hour (about $58/month for an M10) and climb with RAM. The surprise is the jump from the $30 Flex cap to a dedicated cluster that bills 24/7 whether traffic flows or not.
Clerk's Free plan covers 50,000 monthly retained users (MRU) in 2026, so most side projects and early-stage SaaS pay $0. Pro is $25/month with 50,000 MRU included, then $0.02 per user in the 50,001 to 100,000 band. The bill that surprises teams is not per-user overage; it is the feature add-ons, B2B Auth at $100/month, Administration at $100/month, and extra Enterprise SSO connections at $75/month each. Clerk also bills retained users, not signups, so anyone who does not return 24 hours after signing up costs nothing.
Twilio charges $0.0083 per SMS segment in the US as of 2026, but that sticker price is not what lands on your bill. Carrier pass-through fees ($0.0025 to $0.0062 per segment), A2P 10DLC registration charges, number rental, and multi-segment messages typically push the real delivered cost to $0.012 to $0.025 per message, roughly 1.5x to 3x the advertised $0.0083.
Stripe's US rate in 2026 is 2.9% + $0.30 per online card charge with no monthly fee, but the flat 30-cent fee and five add-on meters (international +1.5%, currency conversion +1%, instant payouts 1.5%, disputes $15, Billing 0.7%) push most businesses to an effective 3.2% to 13%. Your real rate is a function of your average order value and how you get paid.
Railway's $5 and $20 plans are usage floors, not your bill. Here is the real 2026 metered invoice at three app sizes, from a $5 side project to a $278/month scaled product.
Auth0's free tier is 25,000 MAU, but the moment a real app needs one paid feature the meter starts near $0.07 per user. A numbers-first 2026 teardown across four app profiles, with the SSO wall and cheaper alternatives priced out.
Supabase Pro is $25 in 2026, but a growing SaaS paid $333 in a real month. A numbers-first 30-day bill across four cohorts, with compute, MAU, and egress itemized.
Three modeled 30-day Vercel bills, the $0.15-per-GB meter that actually moves the number, and when Hobby, a VPS, or a bundled host wins.
Three real 30-day Claude Code bills, the 5.5x token-efficiency math, and when the $200 Max plan beats the API.
