How a FICO Score Is Built
Five factors, five different weights. Move the inputs and watch where the points actually go — and which one is costing you the most.
Your credit profile
Start from a profile, then adjust.
Payment history
35%The single biggest factor. Whether you have paid past accounts on time is the strongest available predictor of whether you will pay the next one.
Amounts owed
30%Mostly credit utilisation — what you owe on revolving accounts against your total limits. Unlike payment history, this one resets every month, which makes it the fastest lever you have.
Length of credit history
15%How long you have been demonstrably creditworthy. The one factor you cannot rush — which is why closing an old card can hurt more than it helps.
New credit
10%Applying for a lot of credit at once looks like distress. Rate-shopping for a single mortgage or car loan is usually treated as one enquiry if done within a short window.
Credit mix
10%Handling both revolving credit (cards) and instalment credit (loans) responsibly shows range. Never open an account you don't need just for this — it's the smallest factor.
Where your points go
Each bar is one factor. The dashed line is the maximum that factor can contribute.
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What would actually move it
Ranked by points available to you right now.
Reading the score
| Band | Range | What it means in practice |
|---|---|---|
| Exceptional | 800–850 | Best available pricing; approval is rarely the question |
| Very good | 740–799 | Above-average terms from most lenders |
| Good | 670–739 | Approved by most lenders at near-standard rates |
| Fair | 580–669 | Approvals likely, but priced for risk; deposits may be required |
| Poor | 300–579 | Limited options; secured products are the usual route back |
How this model works
Each of the five factors is scored 0–100 on its own terms, multiplied by its published weight, and the weighted total is mapped onto the 300–850 range. So a profile scoring 100 on every factor lands at 850, and one scoring zero everywhere lands at 300.
The weights — 35% payment history, 30% amounts owed, 15% length of history, 10% new credit, 10% credit mix — are FICO's own published figures and have been stable for years. What is not public is the shape of the curve inside each factor: exactly how much a 45% utilisation costs versus 25%, or how fast a late payment decays. Those curves here are my own reasonable approximations built from published guidance, and they are where this model and the real one will diverge.
Three things the mechanics tell you
Utilisation is the fast lever. It is recalculated from each statement balance, carries no memory, and is worth 30%. Paying a card down before the statement date can move a score within one cycle — nothing else in the model responds that quickly.
Damage decays but doesn't vanish. A late payment hurts most in the months right after it and fades as it ages, which is why the "months since" slider matters as much as the severity dropdown. Most negatives stay on a US credit file for seven years.
The small factors are traps. Credit mix is 10%, and opening an unnecessary loan to improve it costs you on new credit (10%) and drags down your average account age (part of 15%). The net is usually negative. Similarly, closing an old unused card shortens history and raises utilisation at once.
A note on newer models
FICO Score 10 and 10 T are in circulation alongside the older versions, with 10 T adding trended data — the direction your balances have moved over time, not just today's snapshot. FICO has also released BNPL-aware versions that group buy-now-pay-later plans rather than treating each as a new account; in FICO's own testing, 85% of BNPL users saw score changes under 10 points. Meanwhile mortgage lending is transitioning toward FICO 10 T and VantageScore 4.0. Lenders choose which model to pull, which is the main reason the "score" you see in an app rarely matches the one used to decide your application.
Educational model only. Not affiliated with, endorsed by, or derived from Fair Isaac Corporation. FICO is a registered trademark of Fair Isaac Corporation. This tool cannot and does not reproduce an actual FICO Score, and nothing here is credit, financial or legal advice. Runs entirely in your browser — no inputs are stored or transmitted.