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Faster FDS modeling with professional results

Model dynamic fire simulations in detailed 3D to accelerate and enhance your fire protection analysis.

Are hand calculations and text-driven design holding you back?

Building geometry from scratch is expensive.
Designing models from only text files is error-prone.
Producing results without advanced tools takes too long.

View PyroSim Features

Elevate fire protection engineering to the next level.

Import CAD geometry

Import the architect's model in seconds. Automatically detect BIM data and generate fire-model-specific geometry. Easily understand and navigate your model.

Design simulations graphically

Build in an application tailored to avoiding errors and mistakes. See your model as you work and easily investigate details through intelligent UI.

Manage simulation assets

Control your CPU processing capabilities to optimize simulation time. Maintain multiple simulation configurations for sensitivity analyses.

Deliver professional results

Put the worries of an AHJ to rest. Answer all of their questions with unprecedented clarity by creating plots and videos with advanced controls and information overlay.

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Training and support ready to help you advance

Start delivering better results now

  • Download now
  • Learn the fundamentals
  • Deliver results

FDS + PyroSim

Model a safer world

PyroSim was designed to complement the Fire Dynamics Simulator (FDS) developed by NIST in the US. With state-of-the-art fire research facilities and personnel, they understand the calculations of fire simulation better than anyone.

FDS is the engine powering fire simulations all over the world. PyroSim empowers more engineers to use this technology and elevates its capabilities.

  1. PyroSim provides graphical tools which automatically generate the text-only FDS input file.
  2. PyroSim imports CAD, enables advanced simulation management, and packages its own results manager.

None of this is possible without FDS empowering car park jet fan simulations, sprinkler activation studies, and more.

FDS is free for anyone to download. Do you need PyroSim? We think so. Consider the time not spent constructing your building geometry from scratch in a text editor. Consider the errors caught in real-time and brought to your attention.

Thunderhead Engineering supports you every step of the way. Whether you want in-depth training or self-taught materials, you can learn performance-based design modeling with greater efficiency and proficiency. We design our software for anyone to learn, and our customers are delighted when our support team helps them succeed.

We believe PyroSim will quickly win you over. Try it free for 30 days - complete and unrestricted.

Trusted by experts around the world

Contact our International Partners for assistance in your region.

Leading design firms
International Partners
Years of Updates
Trusted by experts around the world

PyroSim and Pathfinder allow our team to streamline our model builds, use unique techniques and approaches, and provide clean and concise output data. The software saves us time through many of the powerful features, which translates to both cost and time savings to our clients.

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David Stacy
Principal & Founder, Performance Based Fire Protection Engineering, PLLC


Build free for 30 days. Purchase per computer or per network seat. Save by combining multiple licenses.

Annual subscriptions start on the date of purchase and are valid for 365 days. Subscriptions can be renewed as needed in the future.


PyroSim licensed for all users on a single computer.

$ 1100 /yr

Purchase Node-Locked

What's included

  • PyroSim fire dynamics and smoke control simulation.
  • Results visual analysis, management, and export.
  • One year of support and updates.


PyroSim licensed for all computers and users on a network.

$ 1650 /yr

Purchase Floating

What's included

  • Everything in PyroSim Node-Locked.
  • Share pool of Licenses across multiple PCs.
  • Thunderhead License Manager server and support.

Multi-license Discount

Save 50% on all additional licenses across all products.

50% discount


Additional Details

  • Licenses must be purchased at the same time to qualify for the discount.
  • Combine with Pathfinder and Ventus, Node-locked and Floating in your order.
  • Contact Sales to add or modify licenses in an existing order.


No-cost 180-day licenses for non-Commerical, Academic work.

$ 0 /180-days

Apply Here

Additional Details

  • Ask your instructor about existing organizational licenses.
  • Can be renewed every 180-days as needed.
  • Minimal technical support available.

Apply for free government review licenses.

Review licenses are available to authorities (AHJs) for regulatory, non-commercial use.