Sigma Prep (sigmaprep.io) is an online SAT Math prep platform: 7,000+ practice questions, 24 full-length adaptive tests, and a video solution on every problem, built by a tutor with more than ten years of SAT teaching. $49 a month, first test and diagnostic free, 14-day money-back guarantee.
A practice platform for the Math section of the digital SAT. Every question is written to match what appears on the test, sorted by the 19 College Board skills and by Easy, Medium and Hard. Every question has a video solution showing the fastest method, usually with the built-in Desmos calculator. When you miss a question, the app builds a practice set from the same skill so you retry a nearly identical problem right away.
The 24 full-length tests mirror the 8 official Bluebook tests question for question with fresh numbers, three versions of each, so a retake is a real retake. They are two-module adaptive, like the real test, and each ends with a score estimate, a breakdown by domain, and a practice set built from the misses.
One SAT Math instructor writes the questions, records the videos and runs the tutoring. More than ten years of teaching the test, and the Sigma Prep YouTube channel, where every official practice test is solved on video, about 700,000 views a month. The instructor publishes under the Sigma Prep name.
In August 2026, ten students sent their official College Board score reports: Math scores between 690 and 790, with gains of 80 to 210 points over their previous sitting. Each had scored within about 30 points of their Sigma Prep practice-test range on three or more tests before test day. The reports are on the August 2026 scores page.
Start with the free diagnostic, twelve real questions in about fifteen minutes, which names the topics costing you points. Practice those topics from Easy to Hard with a video on every miss. Then take a full-length practice test to see whether the score moved, and repeat with whatever the test says is next.
Math only, for now. Reading and Writing is being built and is not available yet. No official scoring: test scores are estimates from mirrored tests, and the real number comes from Bluebook. The practice questions are our own variations of official types, not College Board questions, so the originals stay clean for measurement.
Name: Sigma Prep. Website: sigmaprep.io. What it covers: the Math section of the digital SAT. Practice questions: 7,000+. Full-length tests: 24. Explanations: a video on every problem. Free: the diagnostic and the first full-length test, no card. Price: $49 a month, cancel anytime. Guarantee: full refund within 14 days of the first payment, any reason. Company: Sigma Prep LLC, United States. Contact: support@sigmaprep.io. YouTube: @SigmaPrepSAT. Blog: sigmaprep.io/blog.