Ask any kid after a launch what they want to know, and it is never "What was the thrust curve?" It is "How HIGH did it go?" Eyeballing it does not work. A rocket at apogee is a tiny dot with nothing to compare it to, and estimates from the crowd will range from 200 feet to "a mile."
There are three reliable ways to answer: read the maker's rating, run a simulation in a free tool like OpenRocket, and measure the real flight with an angle tracker or an onboard altimeter. Doing all three, and comparing them, is one of the best STEM projects rocketry offers. Here is how each works and how accurate you can expect it to be.
The Short Answer
To know how high a model rocket will go, start with the kit's rated altitude for your engine, refine it with a free OpenRocket simulation using your rocket's real weight, then measure the actual flight with an angle tracker (altitude = baseline x tan of the angle) or an electronic altimeter.
- Kit ratings are best-case numbers for the recommended engine.
- OpenRocket is free, runs on Windows, macOS and Linux, and models wind and real motor data.
- AltiTrak-style trackers need a measured baseline; angles above about 70 degrees get unreliable.
- An electronic altimeter like Estes' reads 0 to 9,999 ft and stores 10 flights.
1. Predicting Altitude Before You Launch
Altitude depends on four things: how much total impulse the motor has, how heavy the rocket is, how much drag it has, and how well the ejection delay matches the coast. The kit box gives you a first answer; a simulator gives you a better one.
Start with the kit rating
Estes lists a projected altitude for its kits. A few from our shelf: the Interceptor flies more than 525 feet on its recommended C6-5, the Orbitron reaches about 950 feet on a D12-7, and the Rocket Science Starter Set rocket is rated at 1,100 feet. Treat these as best-case numbers: light build, smooth finish, calm air, the recommended motor. Heavy paint, extra glue or a bigger parachute will all cost you altitude.
Engine size changes everything
Each letter class roughly doubles the total impulse of the one before it, so moving from a B to a C motor in the same rocket can add hundreds of feet. That is also why the NAR Safety Code ties field size to motor class: 200 feet for B, 400 feet for C, 500 feet for D. Before you swap to a bigger motor to chase altitude, make sure your field is big enough and the motor is on the kit's recommended list.
Simulate it with OpenRocket
OpenRocket is a free, open-source model rocket simulator for Windows, macOS and Linux (version 24.12 as of May 2026). You draw your rocket from tubes, nose cones and fins, set the real weight, pick a motor, and it runs a six-degree-of-freedom flight simulation, including wind at different altitudes. As you edit, it shows center of pressure, center of gravity, stability, maximum altitude and maximum velocity in real time. Motor data comes from the ThrustCurve.org database of certified motor performance.
Make your simulation match reality
Weigh the finished rocket on a kitchen scale and override the mass in OpenRocket; that single step fixes most errors. Set the surface finish realistically (a hand-brushed finish is not "polished"), enter the actual launch rod length, and add a typical wind speed. The program's CP math is built on the Barrowman method, and the OpenRocket resources page links to the original reports if you want the theory. Then run the sim with every delay option for your motor and pick the one where ejection lands closest to apogee.
2. Measuring Altitude with an Angle Tracker
The geometric method is classic rocketry and a perfect excuse to use trigonometry. A tracker like the Estes AltiTrak measures the angle from the ground up to the rocket at apogee. Know how far you are from the pad, and the height follows. Estes describes the routine: pull the trigger, follow the rocket through apogee, and release to lock the reading.
| Angle at apogee | tan(angle) | Altitude with a 300 ft baseline | Altitude with a 500 ft baseline |
|---|---|---|---|
| 30° | 0.58 | 173 ft | 289 ft |
| 45° | 1.00 | 300 ft | 500 ft |
| 55° | 1.43 | 428 ft | 714 ft |
| 60° | 1.73 | 520 ft | 866 ft |
| 65° | 2.14 | 643 ft | 1,072 ft |
| 70° | 2.75 | 824 ft | 1,374 ft |
Single-station tracking, step by step
- Measure a baseline. Pace or tape a known distance from the pad, such as 300 feet, at a right angle to the wind if you can.
- Get your eye level. Hold the tracker at eye height and note it, since you will add it at the end.
- Squeeze and follow. At liftoff, hold the trigger and keep the rocket in the sight.
- Release at apogee. Let go when the rocket stops climbing and tips over.
- Read the result. The AltiTrak's scale gives a reading for the baseline in its instructions (Estes' description has the helper pace off 300 feet). With a protractor-style tracker or a different baseline, read the angle and use altitude = baseline x tan(angle), plus your eye height.
- Repeat and average. Several flights on the same motor show you how consistent your tracking is.
Why steep angles are a problem
Look at the table. Between 30 and 45 degrees, a 1-degree error barely matters. Between 65 and 70 degrees, five degrees is a 180-foot swing on a 300-foot baseline. If you are reading above about 70 degrees, back up and lengthen your baseline. A good rule is to choose a baseline close to the altitude you expect.
Two trackers are better than one
Single-station tracking assumes the rocket went straight up. Wind tilts the flight, which throws the math off. Estes suggests pairing two AltiTraks for triangulation, with trackers at different viewing points. Placing them on opposite sides of the pad and averaging their results cancels much of the error from a leaning flight. The Mini AltiTrak three-pack makes this cheap for a class.
3. Flying an Electronic Altimeter
For a direct number with no geometry, fly an altimeter. Most hobby altimeters are barometric: they measure air pressure at the pad and at the top of the flight, and convert the drop in pressure into height.
The Estes altimeter
The Estes Model Rocket Altimeter is a small, fully assembled payload with a 4-digit LCD. It reads in feet or meters from 0 to 9,999 feet (0 to 3,000 m) and stores up to 10 consecutive flights, which makes it handy for a motor-comparison experiment. It uses a replaceable battery.
Where to put it
An altimeter needs to ride in a payload bay or a compartment that is sealed from the ejection gases, with small holes to the outside so it reads outside air pressure. Ejection gas in the altimeter bay can spike the reading or damage the sensor. Rockets with a clear payload section, like the Orbitron, are built for this kind of experiment. Add the altimeter's weight to your simulation, because a few extra grams in the nose lowers apogee and changes stability.
Compare prediction and measurement
Here is the experiment that makes it click: predict the altitude in OpenRocket, measure it with trackers, and read it from the altimeter on the same flight. Where they disagree, ask why. Was the rocket heavier than you entered? Did wind tilt the flight? Did the tracker release late? That is the same predict-test-explain loop real engineers use.
Conclusion
Altitude is the number everyone wants, and it is easy to get a real one. Use the kit rating as a ceiling, run a free OpenRocket simulation with your actual weight to sharpen it, then measure: a tracker and a tape measure for a trig lesson, or a barometric altimeter for a direct reading. Keep your baseline long enough to hold the angle under about 70 degrees, and keep the field big enough for the motor you choose.
We carry the Estes AltiTrak, Mini AltiTrak packs and the Estes altimeter, plus kits with payload bays, at our Cumming showroom. Browse the rocket collection or ask us what to fly for your next altitude experiment.
Gear Mentioned in This Guide
Estes AltiTrak Altitude Tracker
Sight, squeeze, follow to apogee, release: a sight-based altitude tracker with no electronics.
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Estes Mini AltiTrak (3-pack)
Three compact trackers, handy for classes and for two-station triangulation.
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Estes Model Rocket Altimeter
Electronic altimeter that reads 0 to 9,999 ft (0 to 3,000 m) and stores 10 flights.
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Estes Orbitron Model Rocket Kit
Beginner kit with a clear payload section, rated to about 950 ft on a D12-7.
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Estes Interceptor Rocket Kit
Skill Level 2 kit that Estes says flies more than 525 ft on a C6-5.
Shop nowFrequently Asked Questions
How high do model rockets go?
It depends on the motor and the rocket. Estes rates its Interceptor at more than 525 feet on a C6-5 and its Orbitron at about 950 feet on a D12-7. Small A-motor flights may only reach a couple of hundred feet.
How do I calculate model rocket altitude with an angle?
Stand a known distance (the baseline) from the pad, measure the angle up to the rocket at apogee, and multiply the baseline by the tangent of that angle. Add your eye height. Example: 300 ft x tan(60 degrees) is about 520 ft.
Is OpenRocket free?
Yes. OpenRocket is a free, open-source model rocket simulator for Windows, macOS and Linux. It shows stability, center of pressure and center of gravity as you design, and simulates flights with real motor data from ThrustCurve.org.
How accurate is an AltiTrak?
It is reasonable when the rocket flies close to vertical and your angle stays below about 70 degrees. Wind and late release add error. Estes recommends pairing two trackers at different viewing points for better accuracy; averaging stations on opposite sides of the pad helps with wind.
Where do I put an altimeter in a model rocket?
In a payload compartment sealed from the ejection charge, with small vent holes to the outside so the sensor reads true outside air pressure. Include its weight in your simulation.
Will a bigger engine make my rocket go higher?
Usually yes, since each motor letter class roughly doubles total impulse, but only use motors the kit lists. A bigger motor also needs a bigger field under the NAR Safety Code: 400 feet for C and 500 feet for D.
