You don't start with a score of zero — you start with no score at all. Credit scores only exist once a credit file has been established, which requires at least one account that reports to the credit bureaus. Most scoring models require 3–6 months of reporting history before they generate a score, and that first score is calculated from scratch based on your earliest activity — not assigned from a default starting number.
A common misconception is that everyone begins with a score of zero, or some universal starting number. That's not how credit scoring works. If you have no credit accounts — no credit card, no loan, no account that reports to Equifax, Experian, or TransUnion — you are credit invisible: you have no file, and no score is calculated. The CFPB estimates that tens of millions of U.S. adults fall into this category.
The two major scoring models work as follows: FICO requires at least one account that has been open for 6 months and has been reported to the bureau within the past 6 months — with no deceased indicator on the file. VantageScore can generate a score with as little as one month of history on one account. Once those minimums are met, the model calculates your score entirely from your actual account activity — there's no assigned baseline.
FICO and VantageScore both use a 300–850 scale. Most people's first scores land somewhere in the low-to-mid 600s, because the early file is thin — short history, limited mix, and often a single account. There's no guaranteed number; the score reflects whatever the file actually shows. A secured card paid on time for 6 months will produce a different first score than an account with a missed payment.
The fastest paths to a first score: a secured credit card (a deposit-backed card that reports monthly to the bureaus), a credit-builder loan (a structured savings-and-payment product offered by many credit unions), or becoming an authorized user on a long-standing account in good standing. Each of these creates account history that feeds the scoring models once the minimum reporting threshold is met. The CFPB's guidance on building credit covers these options in detail.