Should I just pick the vendor with the lowest estimate?

Only if you’re sure all quotes cover the same scope and assumptions. Otherwise the lowest estimate is often the one that left the most out.

How do good teams forecast mid-project?

From measured progress: how much scope has actually been delivered per iteration, projected over what remains, with the assumptions stated.

Guide · Estimates

Why every software estimate is wrong — and how to read one anyway.

An estimate isn’t a promise; it’s a forecast made with incomplete information. The useful question isn’t “is it right?” but “what does it assume, how uncertain is it, and how will it get better?” Here’s how to read estimates like an engineering manager.

By Nythrex EngineeringUpdated 24 September 2026 1 min read

Idea
Very wide range
After discovery
Narrower: scope & risks known
After design
Narrower still
Mid-build
Forecast from real velocity
Near release
Mostly known

The “cone of uncertainty”: estimates get better as the project reveals what it really is.

Why estimates miss

Unknown unknowns: integrations behave differently than documented; data is messier than expected.
Scope drift: small additions accumulate — see how change requests double budgets.
Optimism: estimates describe the happy path; reality includes reviews, bugs, meetings and waiting.
Different assumptions: two vendors estimate different things under the same title.

How to read an estimate

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Comparing quotes fairly

Put quotes side by side by scope item and assumption, not by total. The cheapest quote often simply excludes things the others included. Our brief generator helps you give every vendor the same starting point.

Frequently asked questions

GuideHow to write a software briefA practical guide to writing a software or AI project brief: the nine sections that matter, examples of good and bad answers, and a free generator.GuideHow change requests double budgetsScope creep arrives as dozens of small “quick” changes. How to run change requests that keep budgets honest without slowing the project down.GuideFixed price vs T&M vs milestonesWhich contract model protects you? Fixed price, time & materials and milestones compared on risk, flexibility, incentives and hidden costs.Free toolAI project effort estimatorFree AI project calculator: six questions → timeline, team, effort in person-weeks and the main cost drivers of your AI project. No signup.

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