Fire Dynamics Simulator (FDS)

free, open-source (public domain) Engineer & Analyze

Free, open-source computational fluid dynamics (CFD) model of fire-driven fluid flow that solves the Navier-Stokes equations for low-speed, thermally-driven flow with emphasis on smoke and heat transport from fires -- used by fire protection engineers worldwide to model fire growth, smoke propagation, heat transfer, and sprinkler activation in buildings; developed and maintained by NIST.

3.6 /5 composite score

C1 5/5 reflects free, open-source distribution with no licensing fees, and C2 2/5 reflects a text-based input format (.fds) and command-line solver rather than a GUI or API. C4 5/5 reflects native .fds format and broad third-party import support (via PyroSim, Thunderhead Pathfinder, and other GUIs), and C5 4/5 reflects integration with Smokeview visualization, PyroSim, and Pathfinder. Firm-size fit is small-team to growing.

Solid

Rubric Scorecard

How we grade →

Criterion	Score	Evidence
Value for the price	5/5	free, open-source (public domain), free tier
Agent Friendliness	2/5	CLI, API: text-based input files (.fds) Source →
Ease of adoption	2/5	--
Portability & lock-in	5/5	2 file formats Source →
Interoperability	4/5	3 integrations

Pricing

Modelfree, open-source (public domain)

Free tieryes

Free vieweryes

Trialyes

Visit Fire Dynamics Simulator (FDS) →

How we verified this: we checked Fire Dynamics Simulator (FDS) against its live site and an independent source — en.wikipedia.org. Nothing on this page is listed from memory. See how we grade. Verified 2026-07-29.

Evidence

File formats

Format	Direction	Support
FDS	native	full -- Native text-based FDS input format
CSV	export	full -- Results data export

Integrations

Smokeview (NIST visualization) (native) PyroSim (Thunderhead GUI) (middleware) Pathfinder (Thunderhead egress) (middleware)

Sources

API docs Formats

Alternatives in Fire & Life Safety

Smokeview

Free, open-source visualization and animation tool for displaying simulation results from NIST Fire Dynamics Simulator (FDS) and CFAST models -- renders particle flow, gas temperature contours, smoke density, and flow vectors in 3D animations and 2D slices, enabling fire protection engineers to understand fire and smoke behavior; developed and maintained by NIST.

3.8/5

CFAST (Consolidated Model of Fire and Smoke Transport)

Free, open-source fire modeling software that simulates fire growth, smoke transport, and temperature distribution throughout building compartments during a fire -- used by fire investigators, safety officials, engineers, and architects to predict how smoke, heat, and harmful gases move and change as a fire progresses; developed and maintained by NIST.

3.4/5

MassMotion

Pedestrian dynamics and evacuation simulation software that models 3D crowd movement, circulation, and emergency egress scenarios -- used by fire protection and life-safety engineers to validate egress code compliance, analyze occupant flow under fire conditions, and optimize emergency response; features adaptive agent-based modeling, automatic way-finding, occupant demographics, and scenario testing; developed by Oasys (part of Arup).

3.2/5

PyroSim

Fire dynamics simulation software that provides a graphical user interface for the NIST Fire Dynamics Simulator (FDS) -- used by fire protection engineers to model fire growth, smoke spread, sprinkler activation, and tenability conditions in buildings; imports CAD/BIM geometry (DWG, DXF, IFC), manages FDS simulations, and produces visualizations and reports; developed by Thunderhead Engineering (founded 1998, Manhattan KS).

3.0/5

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