About Rate of Rise (RoR)

This article introduces the Rate of Rise (RoR).

The Rate of Rise (RoR) plays a crucial role in our Cropster Roast roast logging and analysis tool, serving as an essential component for tracking and analyzing the roasting process.

What is the Rate of Rise (RoR)?

The RoR curve displays the current increase of the bean temperature over some time called the time expression (for example 30 seconds or 60 seconds).

The Rate of Rise (RoR) assists you in three different ways:

  1. Roast speedometer 
  2. Roast track preview 
  3. Heat development navigation 

Roast speedometer (acceleration)

The RoR curve displays the increase (or decrease) in bean temperature over the period given by the Time expression setting (in mathematical terms you can think of this as the derivative of the temperature curve).

It is your real-time roast navigation system that supports you in roasting high-quality coffee at a consistent level. 

To use an analogy, if you think of the bean temperature as the speed of a car, then the RoR gives you the acceleration of the car. High acceleration means the car is going faster and faster, acceleration of 0 means constant speed, and negative acceleration tells you that the car is slowing down. 

So a high RoR tells you that the bean temperature increase is high.

When the RoR starts to decline and gets closer to 0 the increase of bean temperature gets smaller and the bean temperature flattens. If the RoR is negative the temperature of the beans is decreasing, which you want to avoid during the roast.

Roast track preview

The RoR reacts stronger and earlier to temperature changes than the usual bean temperature curve.

When overlaying the reference RoR and the current RoR, you get a visible difference showing you if the coffee develops differently than the reference.

You can see this difference 30-60 seconds before any visible change in the bean temperature. This gained time can be used to take corrective action. 

To use our car example again, if you expect obstacles along your way you don’t want your car to accelerate too quickly since then you may not be able to slow down in time. On the other hand, if your car is not accelerating fast enough it will take forever to get to the desired speed (heat the beans fast enough).

Heat development navigation

The RoR will highlight inconsistent heat development in a more pronounced way than the bean temperature curve.

A bumpy RoR can be a sign of uneven heat development.

This will affect aroma development so it is something that you want to be aware of. Bumps are stronger in the RoR than in the bean temperature, so it is more likely you will notice.


1. How Rate of Rise (RoR) is calculated and what changes with the new settings?

Via Roasting Intelligence (RI) you can adjust your RoR calculation (settings).
Screenshot 2024-07-04 at 10.36.45

The RoR now offers three different settings, Recommended (the default setting), Sensitive, and Noise Smoothing.

For all three settings, the value of the RoR curve shows the temperature increase over some time, how large this period is can be adjusted with the Time expression setting. 

For example, for the default Time expression of 60 seconds, the RoR shows the temperature increase or decrease over the last 60 seconds.

Changing the Time expression setting does not affect the shape of the Rate of Rise curve but only the unit of measurement (C˚/60s, C˚/30s, ...).

Recommended setting This setting offers the best balance between a smooth, interpretable RoR curve and a RoR that responds quickly to changes in the roast temperature.

If you already use the RI5 Rate of Rise nothing will change for you since the recommended setting is the equivalent to this setting with only slightly enhanced smoothing to even out very small spikes in the RoR curve.
Noise Smoothing setting  This setting can be used in case the RoR curve is hard to read due to probe noise when using the recommended settings.

It is geared towards users who had difficulties switching to the RI5 Rate of Rise calculation method because of spiky RoR curves.

It is strongly recommended to inspect the Temperature Probes to be able to use the Recommended setting since the smoother Rate of Rise in this setting comes at the cost of a RoR curve which is less responsive to changes in the bean temperature development.
Sensitive setting  This setting gives a very responsive RoR curve, but depending on the setup the RoR can also be very shaky due to noise in the bean temperature measurements.


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