Free tool
Mix a higher-strength and a lower-strength product to make a strength in between. Enter the three percentages and the final quantity to get the parts and the exact amount of each to use.
Built for pharmacy technician (PTCE) exam prepUse 0 for a diluent such as water or a plain base.
Enter the strengths and final quantity to see the amounts.
Alligation looks tricky until the steps are automatic - Encodr uses spaced repetition to keep PTCE calculations like this one ready for exam day.
Get started freeWrite the higher strength top left, the lower strength bottom left, and the desired strength in
the middle. Subtract across the diagonals, always taking the positive difference:
parts of higher = desired − lower and parts of lower = higher − desired.
Add the parts for the total, then amount of each = final quantity × (its parts ÷ total parts).
The desired strength has to fall strictly between the two you're mixing - you can't mix 40% and
70% into 80%.
Worked example: make 300 g of 50% from 70% and 40%. Parts of 70% = 50 − 40 = 10; parts of 40% = 70 − 50 = 20; total 30 parts. So use 300 × 10/30 = 100 g of the 70% and 300 × 20/30 = 200 g of the 40%. Check: (100 × 70% + 200 × 40%) ÷ 300 = 150 ÷ 300 = 50%. A dilution works the same way with 0% as the lower strength: 500 mL of 5% from a 20% stock and water is 5 parts stock to 15 parts water, so 125 mL of stock and 375 mL of water.
This assumes percentages of the same type (all w/w or all v/v) and that volumes add, which is the standard exam assumption. More pharmacy tech prep: the PTCB exam deck and the exam pass score calculator.
How to use alligation to mix two strengths into a third: the grid, turning parts into volumes, diluting with water, and how to check the answer.
The calculation types behind the PTCE outline (conversions, doses, days supply, percent strength, dilutions, alligation, IV rates) with worked examples.
Log your practice tests - score, breakdown, conditions, date - and get a weighted prediction of your real MCAT score.
Open tool →Calculate your cumulative GPA and BCPM science GPA on the AMCAS 4.0 scale.
Open tool →Enter your exam date, hours needed, and difficulty to see how much less time targeted review actually takes.
Open tool →Enter passages completed and minutes elapsed to see your current pace and whether you are on track to finish the CARS section on time.
Open tool →See the Ebbinghaus forgetting curve for cramming vs. spaced review, and where each review session resets your retention.
Open tool →Enter a course, its credit hours, and how memorization-heavy it is to get a recommended daily and weekly study load.
Open tool →Enter your current grade, the final's weight, and your target grade to see the exact score you need on the final.
Open tool →Calculate your unweighted and weighted GPA (honors +0.5, AP/IB +1.0) side by side - not just pre-med, works for any transcript.
Open tool →Enter total questions and the passing percentage to see exactly how many you can miss and still pass.
Open tool →Enter deck size and your new-cards-per-day pace to see when first exposure finishes and your steady-state daily review load.
Open tool →Enter your grading categories and their weights to see your current overall grade, even with categories still outstanding.
Open tool →Convert instantly between letter grades, percentages, and 4.0-scale GPA points.
Open tool →Convert between metric and imperial units for length, mass, pressure/stress, torque, and volume flow rate - built for engineering coursework, not just everyday conversions.
Open tool →Enter two measurements with their uncertainties to see the propagated uncertainty in a sum, difference, product, or quotient.
Open tool →Enter a discount rate and a series of cash flows to get both the net present value and the internal rate of return.
Open tool →Enter fixed costs, price per unit, and variable cost per unit to see exactly how many units - and how much revenue - it takes to break even.
Open tool →Enter your participation, case write-up, project, and exam weights to see your current grade in a case-method business course.
Open tool →Score your own work against a weighted studio rubric - concept, execution, craft, presentation, and reflection - before a critique or portfolio review.
Open tool →Enter one source once and get correctly formatted citations in APA, MLA, and Chicago side by side, for books, websites, and journal articles.
Open tool →Enter total pages, days available, and how dense the reading is to see how many pages a night it actually takes to keep up.
Open tool →A free, no-signup Pomodoro timer with customizable work and break lengths and a running count of completed sessions.
Open tool →Enter your total credit hours this term to see the weekly study time the standard "2-3 hours per credit hour" rule recommends.
Open tool →Enter your current GPA, credits earned, target GPA, and credits this semester to see the exact GPA you need this term.
Open tool →See whether a property policy met its coinsurance requirement and exactly what it pays on a loss - built for P&C license exam prep.
Open tool →Split a medical bill between you and the plan through the deductible, coinsurance, copay, and out-of-pocket maximum, step by step.
Open tool →Calculate days supply for tablets, oral liquids, and insulin, rounded down to whole days - built for pharmacy technician exam prep.
Open tool →Calculate IV flow rate in mL/hr, drip rate in gtt/min for any drop factor, and infusion time, with the working shown.
Open tool →