Welcome to the world’s only data-driven Marijuana Drug Test Passing Probability Calculator. The drug test passing probabilities and trendlines that this calculator provides are derived from the measurements and urine test results of thousands of cannabis consumers who have submitted their data to us. After your test, please come back and send us your results to increase its efficacy.

Calculates Passing Probabilities For:
➢ Data Plots for Lab Tests
➢ Data Plots for Home Tests
➢ Untampered & Diluted Urine
➢ Blood Draw

Start the calculator below and completely fill in the following forms. When measuring the circumference of your waist, it is essential that you take the measurement at your belly button. The size of your pants is not a waist measurement and may skew the accuracy of your calculation.

Using the Marijuana Drug Test Passing Probability Calculator

After you start the calculator, you will be presented with two data entry forms that are required before graphing your passing probability calculations. The first step is used for physical measurements, followed by the second step where usage patterns and habits are selected. Each field plays a role and has an impact on how long it will take for you to pass a drug test for cannabis.

Enter Biometric Measurements & Usage Patterns

How to Use the Drug Test Calculator - Steps

Below is a quick synopsis of each variable that is used. For a better understanding, it’s recommended that you read about how our calculator was created.

Drug Test Calculator: STEP 01

Gender, Height, Weight, and Waist:
These variables are vital to our calculations as they’re used to determine a user’s Body Mass Index (BMI), body fat percentage, and body fat weight. The weight of a persons body fat is the most significant variable used in all of our calculations.

Since THC is known to be lipophilic, it binds to the fat cells of one’s body after it has been absorbed into the bloodstream. When the level of THC within the blood starts to drop, then the THC that’s stored inside these fat cells is released. Hence, a person that has more fat stored in their body will take much longer time to excrete THC, since the fat cells will hold on to the THC plus its metabolites. Again, it isn’t the weight that matters in this case—it is the weight of body fat a person has. Men typically weigh more than women. However, because women have more fatty tissues on their bodies, it takes a little more time for them to pass a drug test.

Although small, this variable is still statistically important and plays a role in determining how long it will take to pass a drug test.

Your kidneys and liver play a major role when it comes to excreting THC metabolites, whether it is through sweat, saliva, respiration, urine, or blood. As a person ages, their body’s organs experience some changes, for instance, the changes that take place in the kidneys affect the formation of urine. Hence, this also affects how long it will take THC metabolites to leave the body. THC metabolites tend to stay inside the body of someone who’s older for a long period of time, as compared to a younger one. Of course, other factors also contribute in the excretion rate of the THC metabolites.

Drug Test Calculator: STEP 02

Smoking Frequency and Amount Consumed:
With the exception of single use consumers, how often a person uses cannabis and how much they consume each day accounts for the second largest factor when determining a person’s drug test passing probability.

The more you smoke cannabis with THC, the longer it is going to stay within your system. Hence, it’s going to take a lot longer to be fully excreted from the body. As mentioned above, THC metabolites bind to the body’s fat molecules, hence over time these metabolites will start building up every time you smoke. As time goes on, the THC metabolites that have accumulated will be broken down and released into the bloodstream. Therefore, for a regular user, it is going to take a lot longer to completely remove the THC metabolites, which has been built up in their body since the beginning.

Marijuana Potency:
The potency of cannabis you are using is often subjective. However, there is a clear difference in detection times between users that use bottom/low shelf cannabis versus people that use concentrates and dabs. This variable is more significant for infrequent users and for people who just use cannabis once or twice.

Metabolic Speed and Cardio Activity Level:
There is a strong correlation between the belief a person has about their metabolism and whether or not they pass a drug test. In fact, a person’s metabolism coupled with their cardio activity level accounts for the third largest factor used in our calculations.

When you exercise more, the quicker you will excrete THC from your fat cells and into your bloodstream; hence the quicker it will leave the body. Moreover, doing more cardio is going to make sure that your body stores a lower quantity of THC inside your fat cells. Plus, any THC that does get stored inside the fat cells of a person who exercises regularly, ends up releasing a lot more faster into your bloodstream in order to get excreted as quickly as possible.

Understanding the Drug Test Calculator Result Page

How to Use the Drug Test Calculator - Results

After calculation, a line chart representing several unique drug test passing probabilities will be plotted, accompanied by a Graph Legend. On the left side, the Y-Axis of the line chart represents the passing percentile while on the bottom, the X-Axis represents the number of days it should take to pass. Each plot line is color coded by Test Type.

In the example above, this user would have a 60% chance of passing a home drug test kit at around 31 days without diluting their urine (see the Blue Star). If this person prepared and correctly diluted their urine before the test, then the odds of them passing a home test would significantly increase; either 60% passing at ~19 days or 90% passing at 31 days.


The same dilution concepts can be applied to lab urinalysis. Highlighted on the line chart example and indicated by the Graph Legend, a 75% chance of passing a lab test at 33 days without dilution can change to a 75% chance of passing at 26.5 days by using proper dilution techniques.

If you’re providing a Blood Draw, know that it isn’t uncommon for people to fail several weeks after cessation, as reported by many cannabis consumers and illustrated in our independent study.

The generally held belief that THC cannot be detected in blood after a few days is patently false. Active and inactive THC metabolites in blood can be detected up until a few days before metabolites are no longer detected in urine. Take note that Blood Draw passing probability results are not graphed for people who are infrequent users.

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