Article updated: 2024 Feb 13 / Author Leslie Griver, Robert Henry

THC Detox Calculator: Discover how long THC and Delta-8 THC remain detectable in drug tests.

This THC detox calculator shows how long delta-8 THC and delta-9 THC stay in your urine, blood, and saliva and are detectable by the drug test.

The similarity in the names of delta-8-THC and delta-9-THC is an indication of how close they are structural. The only difference is the position of one double bond in one ring within the THC molecule. That similarity carries over into their major metabolites.

The metabolism of delta-8-THC and Delta-10 THC is the same as for delta-9-THC, so the calculator can be used for both of them.

With the calculator, you can also see how different remedies will help you detox faster.

THC detox calculator


How to use the calculator

  1. Enter your height and weight. The calculator needs this information to estimate your BMI, body fat percent, and metabolism speed.
  2. Choose the frequency of smoking. This is required because it affects the amount of THC that gets into your system and the time required to detox.
  3. Choose the THC content of your weed. This is also required to estimate the amount of THC that gets into your system.
  4. Select if you want to use activated charcoal during the detox or if you will follow the healthy diet plan. This will affect how much time will you need to get THC out of your system.

What if I use edibles?

If you use edibles, just choose the “High” THC content in the calculator.

How to read the results

The results will show you 3 charts. The charts show the change in concentration of THC metabolites in the urine, in the blood, and in the hair over the time period.

We consider day 0 as the last day when you smoked marijuana.

THC in the urine chart

This chart will also show the day when the concentration of THC metabolites in the urine will drop below the 50ng/ml cutoff level.

If you select the “follow healthy diet” option, you will also see a spike in concentrations after ~7 days. That’s because when you start to follow a healthy diet, your body will start using fat as an energy source.

So THC from the fat cells will be released into the blood and temporarily increase the THC concentration in blood and urine.

The spike will appear after ~7 days because our body needs some time to start to burn fat,

THC Detox calculator: THC in the urine concentration chart

THC in hair chart

Here you’ll see the concentration of THC metabolites in the 1.5-inch hair sample closest to the head. This is the sample used during the hair drug testing.

hair sample for drug test

You will see that the concentration grows over time. That’s because even when you stop smoking, you still have THC in the blood. Part of that THC deposits into the hair. The hair grows approximately 0.5 inches per month, so it requires some time for this part of the hair to become clear.

For example, if we choose another time period, let’s say 120 days. We’ll see that the concentration of metabolites goes down as your system removes THC and hair grow.

thc detox calculator: THC in hair chart over long timeframe

How our THC detox calculator works

Our calculator uses a complicated math model of the human metabolism of marijuana. This model is based on dozens of scientific research studies. You can find the links to the studies at the bottom of the page.

We model the processes involved in the metabolism of marijuana and calculate the number of THC metabolites in the urine, blood, and hair each hour.

Here’s what we consider during the calculations:

Basics of marijuana metabolism

When we smoke THC gets into the blood. From the blood, most of the THC is absorbed by the fat tissues. Then THC is slowly released back into the blood and is taken by the tissues again.

With the blood, THC gets into the liver, where it goes through 2 phases of metabolism: modification and conjugation.

After the second phase, THC metabolites are moved into the intestines and bladder.

Part of these metabolites is reabsorbed back into the blood from the renal tubules and intestines.

This is a very basic explanation. If you want, you can read the detailed explanation here: The Ultimate Guide to Marijuana Metabolism


We analyzed and used the information from the latest scientific studies to create this calculator. However, you should understand the human body is a very complex system.

It’s impossible to create an exact math model of processes taking place in the body.  So the results are approximate, but they provide an understanding of how much time marijuana stays in the body. And how much time is required to get it out of the system.