What you need for a software project estimate

PLIXIO teamPublished 27 October 2026Updated 27 October 2026

In short

A good estimate depends more on the information you provide than on the estimating method.
Ten inputs make the difference: the problem, users, workflows, data, integrations, reports, security, volume, deadline and who will maintain the application.
Ask for a phased estimate with ranges and written assumptions. A single number for an unanalyzed project is a guess.

The cost of a software project is, above all, a function of uncertainty. The less a vendor knows about what must be built, the wider the estimate range, or the larger the risk margin hidden in the price. This guide shows what to prepare to get an estimate you can rely on.

The ten inputs that matter

The business problem. What does not work today, and how you will know the project succeeded. One measurable sentence is worth more than a long feature list.
Users. How many user types exist (operators, managers, customers, partners) and what each can do.
Main workflows. The steps of an order, an approval or a service call, start to finish, including frequent exceptions.
Data. Which entities exist (customers, products, contracts), where they come from and what history must be migrated.
Integrations. Which systems the application must talk to: ERP, CRM, invoicing, RO e-Factura in Romania, couriers, payments. For each: is there a documented API?
Reports. What leadership needs to see, and how often.
Security and compliance requirements. Personal data, financial data, sector obligations such as NIS2.
Volume. Concurrent users, transactions per day, documents per month.
Deadline and constraints. Is there a fixed date (a legal obligation, a sales season)? What budget is available?
Who maintains it. An in-house team or the vendor? The answer shapes the technology choice.

What drives cost most

Factor	Why cost rises	How to reduce it
Integrations	Every external system has its own rules, limits and failures.	Check early which APIs exist and who can open access.
Process exceptions	Rare cases often take longer than the main flow.	Separate exceptions that must be automated from those that can stay manual.
Data migration	Legacy data is rarely clean.	Decide how much history to migrate and who validates the result.
Security requirements	More controls mean more development and testing.	Choose the requirement level by risk, not the maximum available.
Mid-project changes	A new requirement during build costs more than during analysis.	A short discovery up front and a clear change-approval process.

Three kinds of estimate

Ballpark estimate

Given after a first conversation as a wide range. It helps decide whether the project makes sense, not sign a contract.

Phased estimate after discovery

After a short analysis you receive the scope, the architecture and a range for each phase, along with the assumptions. This is the form we recommend for most projects.