How to use PharmaWallah Calculators
Master your pharmacy calculations
PharmaWallah Calculators make pharmaceutical, laboratory, clinical and mathematical calculations faster and easier. Enter your values, select the right units, and review your result. This guide works for all 106 of them.
Quick tour
Step 1
Choose your calculator
Search by name, or open the subject you're studying — the index groups the calculators into 10 subjects.
Before you start
Have these ready
What to bring
- Your experimental or observed values
- The unit each value was recorded in
- Any constants your manual gives you
- Sample or drug details, if the calculation needs them
- Instrument readings, if you took any
- How many decimal places or significant figures are expected
Checklist
- Step 1: Check the practical or the question
- Step 2: Identify every value it needs
- Step 3: Confirm each unit
- Step 4: Enter the values carefully
- Step 5: Read the result
- Step 6: Verify it before you use it
Step 1
Choose your calculator
Choose the calculator that matches the calculation or experiment you are doing. Search by name, or browse by the subject you meet it in.
The 10 subjects
- Pharmaceutical Chemistry
- Unit Conversion
- Pharmaceutics
- Biopharmaceutics & Pharmacokinetics
- Pharmacology
- Pharmaceutical Analysis
- Physiology
- Microbiology
- Pharmaceutical Engineering
- Clinical & Hospital Pharmacy
Not sure which one? Search for the quantity you need, such as “dilution”, “half-life” or “yield”, and read the one-line description under each name.
Step 2
Understand the calculator screen
Every calculator is built from the same parts. Not every calculator has all of them, so look for the ones yours has.
- 1Title. The calculator's name and its subject.
- 2What it calculates. One or two lines under the title. Read this first.
- 3Mode tabs. On some calculators. Each tab works out something different.
- 4Try an example. On many calculators. Fills in sample values so you can see how it works.
- 5Input boxes. Where your values go. Hints sit under some boxes.
- 6Units. Fixed beside the box, or a dropdown you choose from.
- 7Result. The answer, its unit and what it means.
- 8Calculate and Reset. Reset is on almost every calculator. Calculate only appears on lab-practical tools.
- 9Table and graph. On calculators that take several readings.
- 10How this is calculated. The formula and the working. Closed until you open it.
- 11Notes and warnings. Limits of the method, and the educational-use notice.
Step 3
Enter your values
Enter values exactly as your experiment, practical manual, question or dataset gives them.
Rule 1
Numbers only in number boxes
The unit is shown beside the box or chosen from its dropdown, so type the number alone.
Rule 2
Pick the unit you recorded
If a box has a unit dropdown, choose the unit your value was measured in. The calculator converts for you.
Rule 3
Don't mix units yourself
Where a box has a fixed unit and no dropdown, convert your value to that unit before typing it.
Rule 4
Check the decimal point
0.5, 5 and 50 differ tenfold each. One slipped point changes the answer by the same amount.
Rule 5
Keep your raw values
Enter what you observed. Only transform a value (average it, convert it) when your practical tells you to.
Many calculators have a Try an example button. It fills in sample values so you can see how the calculator works before you enter your own.
Step 4
Use the unit dropdowns
Where a box has a dropdown beside it, choose the unit that matches your recorded value. The calculator converts it for you.
Wrong units can produce completely different results: 5 mg/mL is 5000 µg/mL.
If the unit is printed inside the box instead of in a dropdown, it is fixed. Convert your value to that unit before you type it.
Step 5
Needed, optional and calculated values
A calculator tells you what it still needs. You don't have to guess.
- Needed. Most boxes are needed. Until they are filled, the result card stays empty and says which values it is waiting for.
- Optional. Some labels end in “(optional)”. Leave them blank and the calculator still works. Fill them in to get an extra result or a more precise one.
- Calculated for you. Intermediate values, such as a converted unit or a percentage for each row, are worked out and shown. You don't type them.
Step 6
Getting the result
On most calculators there is nothing to press: the result appears as soon as the needed values are in. Lab-practical calculators have a Calculate button.
Before you read the answer
- 1.Enter all the needed values.
- 2.Check the units.
- 3.Check the values once more.
- 4.Press Calculate, if your calculator has the button.
- 5.Read the result card.
If a box turns red or a message appears, correct that value first. The result won't show until it's fixed.
Step 7
Understand your result
The result card gives the number, its unit and, on most calculators, a line saying what it means.
The value
Is it the size you expected?
The unit
Is it the unit your answer needs?
Decimal places
Round as your manual asks.
Significant figures
No more than your data supports.
Scientific sense
A yield over 100% or a negative mass means a wrong input.
Expected range
Compare with the range given in your practical.
The calculator does the arithmetic. You are responsible for entering correct data and interpreting the result.
Lab-practical calculators also build a lab-record card. Use Copy to paste it into your notes, or Download card and Print.
Step 8
The formula and working
Open “How this is calculated” on any calculator to see how the result was obtained. It's closed until you tap it.
Match each letter in the formula to a box you filled in. Then follow the working to see your own numbers substituted. It's useful for practical records, assignments and viva preparation, and it's the quickest way to spot a value in the wrong box.
Step 9
Tables
Calculators that take several observations, such as readings over time or replicates, have a table. You can enter and compare them together.
- Enter values row by row.
- Check each row belongs to the right time, sample or replicate.
- Watch for a value shifted into the row above or below.
- Columns the calculator fills in are shown in its own results. Don't type them.
Step 10
Graphs
Where a calculator draws a graph, it shows the relationship and trend in your data.
Check
- Axis labels
- Units
- Data points
- The trend
- Slope and intercept
- R², if shown
Ask whether the graph shows the relationship you expect. The x-axis is the variable you set; the y-axis is the one you measured. Common types are time against concentration, time against absorbance, concentration against response, calibration curves, and stability or kinetics plots. R² closer to 1 means the points sit closer to the line.
Step 11
Reset
Use Reset when you start a new calculation or enter a different dataset.
Reset clears your current inputs and result. Write down or copy anything you need first.
Step 12
Common errors and how to fix them
The result card stays empty
A value it needs is still blank. The empty card says which ones.
A box turns red
The value isn't allowed there, for example a zero you divide by, or a negative mass. Read the message under the box.
The number looks wrong
Usually it's a unit. Check the dropdown matches what you recorded.
- Input values
- Units
- Decimal points
- The formula
- Any conversion the practical expects
The graph looks odd
Look at the table that feeds it.
- Rows in the right order
- No missing observation
- X and Y values not swapped
- Units
You're on the wrong mode
Many calculators have tabs at the top that change what is worked out. Check the right one is selected.
On the website
Using the calculators on the website
- Find it: Calculation tools has a search box and a subject list.
- Go back: under every calculator there's an All calculators button.
- On a phone browser: the same page stacks into one column, and number boxes open the number keypad.
- Needs internet to load. No account is needed.
On the app
Using the calculators on the mobile app
- The same calculators. The app runs the very same calculator screens as the website, so everything in this guide applies.
- Works offline. Every calculator works with no signal, in the lab or on the ward.
- Home, Browse, Saved at the bottom of the screen. Tap the ☆ on a calculator to save it; recently opened ones appear on Home.
- Back arrow at the top left of every calculator returns to the list.
- Android only for now. There is no iPhone download yet. On an iPhone, use the website in Safari.
Website and app compared
| Feature | Website | Mobile app |
|---|---|---|
| Every calculator | Yes | Yes |
| Search | Yes | Yes |
| Inputs, units, results, tables, graphs | Yes | Yes (same calculators) |
| Formula and working | Yes | Yes |
| Reset | Yes | Yes |
| Copy a lab-record result | Yes | Yes |
| Download or print the lab-record card | Yes | Share instead |
| Works with no internet | No | Yes |
| Saved and recent calculators | No | Yes |
| Account needed | No | No |
Best practice
7 golden rules
- 1Read the practical or question first.
- 2Identify every variable it needs.
- 3Use the correct units.
- 4Enter values carefully.
- 5Check the formula and working.
- 6Review the result and its unit.
- 7Record your final answer clearly.
In the lab
From experiment to practical record
The workflow for a lab practical, from the bench to the page.
Important
Don't blindly trust the result
PharmaWallah Calculators are tools for calculation and learning. Always check that your inputs, units, formula and interpretation are correct.
Where your instructions win
If a method or rounding rule differs from the calculator, follow:
- Your practical manual
- Your course instructions
- Your instructor's requirements
- Laboratory SOPs
- Your institution's guidelines
Clinical calculators
Dose, renal, hepatic and other clinical calculators are for study and reference only. Their results are not a substitute for professional clinical judgement, current guidelines or a prescriber's decision, and must not be used to treat a real patient.
Cheat sheet
Quick start
- 1Choose your calculator
- 2Read what it calculates
- 3Gather your values
- 4Enter the values
- 5Select the correct units
- 6Watch the result appear, or press Calculate
- 7Review the result and its unit
- 8Check the formula and your data
- 9Record your answer
That's it. Calculate smarter with PharmaWallah.
Start calculating