Website, pricing, platforms and company facts side by side.
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| Website | nbmecalc.com | opalstack.com |
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| Company | Startup from the United States · 1 - 9 employees · 2026 | — |
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In their own words, as submitted to SaaSHub.
NBMEcalc helps medical students interpret Clinical Science Mastery Series (CMS) form results during USMLE Step 2 CK preparation. Enter a CMS score or percent-correct result to review subject-level study signals across Internal Medicine, Surgery, Pediatrics, Obstetrics and Gynecology, Psychiatry,...
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What each product offers, as listed by its team.
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As answered by people managing NBMEcalc and Opalstack.
NBMEcalc's answer
NBMEcalc combines multiple practice assessment sources—including NBME, UWSA, Free 120, AMBOSS Self-Assessment, and CMS—into one USMLE planning range. Instead of presenting a single “magic” score, it shows a 95% confidence interval, supports Step 1, Step 2 CK, and Step 3, and makes its methodology and limitations public.
NBMEcalc's answer
NBMEcalc is designed for students who want to interpret several practice assessments together rather than relying on one score in isolation. The core predictor is free, works without registration, supports multiple assessment sources, and clearly communicates the uncertainty around every estimate.
NBMEcalc's answer
NBMEcalc is built for medical students and graduates preparing for USMLE Step 1, Step 2 CK, or Step 3. It is especially useful for test-takers who have results from several practice assessments and need a clearer view of their score range, pass readiness, and study trajectory.
NBMEcalc's answer
NBMEcalc began in late 2025 after frustration with closed-source score predictors and one-size-fits-all advice. The first prototype was created to combine multiple practice assessment sources into a more transparent planning range. The project later added a public methodology, confidence intervals, free score prediction, downloadable reports, and multi-exam tracking.
NBMEcalc's answer
NBMEcalc is a responsive browser-based application built with Next.js, React, and TypeScript. It uses statistical score-normalization and weighting logic to combine multiple practice assessment results. The application is mobile-friendly and can be used directly in a web browser without installing native software.
NBMEcalc's answer
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When comparing NBMEcalc and Opalstack, you can also consider the following products.
The AMBOSS Qbank app for UMSLE® Step and NBME® Shelf exams is the ultimate exam preparation and study resource for medical students. Dive into thousands of USMLE-style exam questions to enhance your knowledge and prepare for all your exams.
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UWorld Test Prep offers test preparation, practice tests and assessments for more than 1 million users who are preparing for USMLE, ABIM, ABFM, NCLEX, MCAT, SAT, ACT, CPA and CFA examinations.
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