Formula Used
BMI: BMI = weight kg ÷ height m².
Adjusted window: base window × dose factor × session factor × body fat factor × BMI factor × metabolism factor × activity factor × cutoff factor × margin factor.
Cutoff factor: cutoff factor = default cutoff ÷ entered cutoff, raised to 0.35.
Remaining days: remaining days = adjusted window − elapsed days.
Positive risk: risk = 100 ÷ [1 + e^((elapsed days − adjusted window) ÷ spread)].
The formula is a cautious model. It is not a medical, legal, workplace, or laboratory decision rule.
How to Use This Calculator
Choose the sample type first. Select urine, saliva, blood, or hair. Pick the closest use frequency. Enter the last use date and time. Add an estimated THC amount, sessions per week, body fat, weight, and height. Choose metabolism and activity estimates. Enter the test cutoff if known.
Press Calculate to view the result above the form. Use CSV for spreadsheet records. Use PDF for a simple report. Treat every output as an estimate only. Ask the testing provider for official cutoff and confirmation details.
Understanding THC Detection Estimates
THC testing is not a simple countdown. The body stores THC metabolites in fat tissue. They leave at different speeds for each person. A statistical calculator can only estimate a range. It cannot confirm a pass or fail result. The most useful output is a probability band, not a promise.
Why Inputs Matter
Sample type changes the estimate first. Urine tests usually look for THC-COOH, a metabolite. Saliva and blood tests often reflect more recent use. Hair tests can show a longer history, but timing is less precise. Frequency also matters. A single exposure may clear faster than repeated exposure. Regular use can create a larger stored amount. Body fat, activity level, and metabolism can shift the range.
How The Calculator Thinks
This tool starts with a baseline window for the chosen sample. It adjusts that window with use frequency, approximate amount, body fat, body mass index, metabolism, and cutoff level. A lower cutoff can extend the estimated window. A higher cutoff can shorten it. The result then compares elapsed time with the adjusted window. A logistic curve converts that gap into a cautious positive risk estimate. This keeps the output gradual, because real tests do not switch from certain positive to certain negative in one day.
Reading The Result
A high risk percentage means the entered timeline remains inside the likely detection zone. A moderate percentage means results are uncertain. A low percentage means the timeline is beyond the model range, but not guaranteed. Labs, sample quality, medical factors, and product strength can change outcomes. Confirmatory testing may also differ from screening.
Responsible Use
Use this page for education, record keeping, and statistical planning. Do not use it to avoid lawful or required testing. Do not rely on dilution, detox drinks, or internet tricks. They can be unsafe and unreliable. When results matter for work, court, sport, or treatment, ask the testing provider about sample type, cutoff, and confirmation rules. Honest communication is safer than guessing. Keep written notes about dates, products, and dose estimates. Better records make the model clearer. They also help medical, legal, or workplace conversations stay factual and calm. Retest choices should follow official instructions, not online timing myths or pressure.
FAQs
Can this calculator guarantee a negative result?
No. It gives a statistical estimate only. Real results depend on lab methods, cutoff levels, sample quality, product strength, and personal biology.
Which sample type usually detects THC longest?
Hair testing often covers the longest history. Urine may detect metabolites longer than saliva or blood. Each method has different limits and confirmation rules.
Why does body fat affect the estimate?
THC metabolites are associated with fat storage. Higher body fat can increase the modeled window, but the effect varies between people.
What does cutoff level mean?
The cutoff is the level used to mark a sample as positive or negative. A lower cutoff can increase the estimated detection window.
Does heavy use change the result?
Yes. Repeated use can increase stored metabolites. The calculator uses a longer baseline window for regular and heavy patterns.
Are detox drinks included in the formula?
No. The calculator does not model detox drinks or test evasion methods. Such claims can be unreliable and may create risks.
Why is the result shown as a probability?
Detection is uncertain. A probability gives a range-based estimate instead of a false yes or no answer.
Can I export the result?
Yes. Use the CSV button for spreadsheet records. Use the PDF button for a simple report with your estimated result.