Veterinary calculators for vets and nurses. Full working, every time.
36 free clinical calculators. No login, no app to install, no trial that expires. Built by Dr Duncan Houston, an emergency veterinarian, to work one-handed on a phone propped against a kennel door.
- 100% free
- No login, no app to install
- Shows its full working
In a crash
The ones you want already open when it goes bad. Bookmark this page or add it to your home screen.
All 36 clinical calculators
- Emergency & critical care
Albumin Dose Calculator
Albumin deficit or g/kg dosing for hypoalbuminaemia, with volumes for human 25%, 20%, 5% and canine albumin, infusion rate, predicted response and the reaction and overload cautions built in.
Basis: Basis: Deficit (g) = 10 x (target minus current albumin, g/dL) x kg x 0.3, capped at 2 g/kg per day; product volumes and rates from published canine and feline protocols and manufacturer labelling
Open calculator - Anaesthesia & analgesia
Anaesthetic, Sedation & Analgesia Drug Calculator
40 drugs and 4 combination protocols for dogs and cats, with editable vial concentrations, patient risk flags, interaction checks and printable cage sheets.
Basis: AAHA Anesthesia & Monitoring (2020) and Pain Management (2022) guidelines
Open calculator - Anaesthesia & analgesia
Anaesthetic Risk Estimator
Understand your pet's anaesthetic risk before surgery or a dental, and the questions worth asking your own vet beforehand.
Basis: This tool produces a non-validated educational planning score from 1 to 10.
Open calculator - Dosing & infusions
Antibiotic Dose & Choice Calculator
Empirical antibiotic selection when you do not have a culture and sensitivity yet: pick the species and the presentation, and get the stewardship-ranked first choice.
Basis: The dose at your patient’s weight, when culture is non-negotiable, and the warnings that actually matter.
Open calculator - Dosing & infusions
Antihistamine Dose Calculator
Weight-based doses of single-ingredient antihistamines for dogs and cats, and why most allergy packets on the shelf must never be given.
Basis: Safe starting doses for diphenhydramine, cetirizine, loratadine, chlorphenamine, fexofenadine and clemastine.
Open calculator - Dosing & infusions
Antithrombotic Calculator: When and Which to Use
Decide whether a dog or cat needs antithrombotic therapy, choose between antiplatelets and anticoagulants, and get weight-based doses with monitoring and stopping guidance.
Basis: Doses follow the CURATIVE consensus (J Vet Emerg Crit Care 2019) as summarised for clinical use.
Open calculator - Fluids & electrolytes
Blood Gas Calculator
Interpret arterial and venous blood gas results with anion gap, base excess and an expected-compensation check.
Basis: Anion gap = (Na + K) - (Cl + HCO₃), with expected-compensation check
Open calculator - Emergency & critical care
Blood Transfusion Volume Calculator
Volume of packed red cells or whole blood to reach a target PCV, plasma volumes for coagulopathy, plus rate and monitoring milestones.
Basis: Weight × blood volume factor (~90 mL/kg dog, ~60 mL/kg cat) × PCV gap ÷ donor PCV
Open calculator - Reproduction
Caesarean Planning Calculator
Timing, drug selection and preparation planning for an elective or emergency caesarean.
Basis: Progesterone drop and gestation-length timing
Open calculator - Scoring & staging
Canine Pain Calculator
A validated behaviour-based tool for assessing acute pain in dogs.
Basis: A pictorial 0–4 scale for acute pain in dogs. Scores of 2 and above prompt a reassessment of the analgesic plan.
Open calculator - Dosing & infusions
Chinese Herbal Medicine (TCVM) Dose Calculator
Granule and powder dosing for 174 formulas and single herbs across 9 species, with patient risk flags and traditional contraindication lists.
Basis: Chi University / Jing Tang dosing convention. A supplier convention, not an efficacy evidence base
Open calculator - Dosing & infusions
Constant Rate Infusion (CRI) Calculator
CRI concentrations, fluid bag additions and pump rates, with a printable infusion label.
Basis: mL/hr = mcg/kg/min × kg × 60 ÷ concentration in mcg/mL
Open calculator - Fluids & electrolytes
Constipation, Megacolon & Colonoscopy Prep Calculator
Weight-based PEG 3350 treatment plans for feline deobstipation, dog and cat colonoscopy bowel prep, maintenance laxative dosing and the in-house PEG electrolyte solution recipe.
Basis: This tool doses in-hospital treatments: nasogastric lavage, IV maropitant and enemas. Pet owners: if your dog or cat is straining, not passing faeces or vomiting, please see your vet.
Open calculator - Dosing & infusions
Corrected Chloride Calculator
Correct the measured chloride for changes in free water and sodium, so you can tell a true chloride disturbance from a water problem in one step.
Basis: This tool interprets serum or plasma chloride against sodium. It supports, and never replaces, blood gas analysis and clinical judgement.
Open calculator - Emergency & critical care
CPR Timer
Two-minute cycle timer with compressor swap prompts, drug interval reminders and a running event log.
Basis: RECOVER CPR cycle structure
Open calculator - Endocrine & metabolic
Daily Calorie Calculator
How many calories your dog or cat actually needs each day, from resting energy requirement adjusted for age, desexing and activity.
Basis: Estimate your animal's daily calories, resting energy requirement (RER) and food portions in grams, cups or meals.
Open calculator - Dosing & infusions
Dilution Calculator
Enter what is on the vial, what you need and the final volume. Works in %, mg/mL, mcg/mL, g/L, mEq/mL, IU/mL and ratio strengths.
Basis: C1V1 = C2V2, with safer bag, reverse-check and serial-dilution workflows.
Open calculator - Endocrine & metabolic
DKA vs HHS Calculator
Separate diabetic ketoacidosis from hyperosmolar hyperglycaemic state, with corrected sodium and effective osmolality.
Basis: Effective osmolality = 2 × Na + glucose (mmol/L); glucose-corrected sodium
Open calculator - Emergency & critical care
Emergency Drug Calculator
Crash-cart doses and draw-up volumes by body weight for the drugs you reach for first, all on one screen.
Basis: Standard emergency dose ranges, RECOVER-aligned for arrest drugs
Open calculator - Emergency & critical care
Emergency Vet Triage Questions: What to Ask Before the Consult
A structured triage tool for veterinary nurses and reception staff.
Basis: Trained veterinary nurses, technicians and reception staff triaging patients that have already arrived at a clinic.
Open calculator - Scoring & staging
Feline Pain Scale Calculator
Four validated feline pain tools in one
Basis: CSU: holistic 0–4. Feline Grimace Scale: 5 facial units, /10 (treat ≥4). UNESP-Botucatu MCPS: 10 items, /30 (treat ≥8). Glasgow CMPS-Feline: 7 questions, /20 (treat ≥5)
Open calculator - Endocrine & metabolic
Glucose Curve & Insulin Dose Calculator
Plot a blood glucose curve, identify nadir and duration, and work through the next insulin dose adjustment.
Basis: Nadir, duration and insulin overlap assessment
Open calculator - Dosing & infusions
Hospital Cage Card Generator
Add patient identification, CPR or DNR status, behaviour, isolation precautions, diet, NPO instructions and essential nursing alerts, then print it for the cage, kennel, ward, ICU or isolation area.
Basis: Create a clear, printable veterinary cage card for a dog or cat in hospital.
Open calculator - Dosing & infusions
Hospital Handover (I-PASS)
Type each patient's case notes during the shift, then print or copy a clean I-PASS handover for the next vet. Patients sort sickest first within each department and your draft auto-saves in this browser.
Basis: I-PASS uses five core elements: Illness severity, Patient summary, Action list, Situation awareness and contingency planning, and Synthesis by receiver.
Open calculator - Dosing & infusions
Hospital Patient Chart
Vitals and care tasks on top, medications and IV fluids below, every due time highlighted so nothing gets missed.
Basis: Daily cage sheet with automatic dose calculations.
Open calculator - Scoring & staging
IRIS Kidney Disease Staging Calculator
Stage and substage chronic kidney disease on creatinine and SDMA, with proteinuria and blood pressure substaging.
Basis: IRIS CKD staging guidelines
Open calculator - Dosing & infusions
IV Drug Compatibility Checker
Which injectable drugs and fluids can share one IV line, catheter lumen or bag in a hospitalised dog or cat.
Basis: "Compatible" means physically compatible at usual concentrations for a brief Y-site contact; results depend on concentration, diluent, pH and brand.
Open calculator - Fluids & electrolytes
IV Fluid Calculator
Maintenance, dehydration deficit and ongoing losses combined into a single hourly rate, with drip and pump settings.
Basis: Maintenance + deficit (% dehydration × kg × 10 mL) + ongoing losses
Open calculator - Fluids & electrolytes
IV Fluid Therapy Calculator
The calculator recommends the best-fit IV fluid, calculates the fluid rate, plans shock boluses, and doses common bag additives and electrolyte corrections for the actual patient and bag size.
Basis: Enter a patient's blood results, hydration status and clinical signs.
Open calculator - Scoring & staging
Modified Glasgow Coma Scale Calculator
Score motor activity, brainstem reflexes and level of consciousness for a head trauma prognosis.
Basis: Modified Glasgow Coma Scale (MGCS): three categories scored 1 to 6, total 3 to 18
Open calculator - Fluids & electrolytes
Phosphate Supplementation Calculator
Potassium phosphate infusion rates for hypophosphataemia, with the calcium and potassium cautions built in.
Basis: mmol/kg/hr phosphate infusion with combined potassium load check
Open calculator - Scoring & staging
Pregnancy & Due Date Calculator
Work out gestation stage, the whelping or queening date and what to prepare when, from the mating dates you have.
Basis: Pick the species, enter one date, and get an estimated birth date plus a full pregnancy timeline.
Open calculator - Fluids & electrolytes
Sodium Correction Calculator
Safe rates of change for hyponatraemia and hypernatraemia, with free water deficit and the fluid choice to get there.
Basis: Chronic or unknown duration: 0.5 mmol/L/hr and 10 to 12 mmol/L/24 hr ceilings. Acute cases branch separately
Open calculator - Scoring & staging
Trauma Triage Score Calculator
Animal Trauma Triage score across six categories, to grade severity and estimate survival on presentation.
Basis: Animal Trauma Triage (ATT): six categories scored 0 to 3, total 0 to 18
Open calculator - Reference
Unit Converter
Veterinary unit conversions in both directions: SI and conventional, weights, doses, glucose, creatinine and more.
Basis: SI and conventional unit conversion factors
Open calculator - Scoring & staging
Veterinary IVDD & Spinal Staging Calculator
Grade spinal injury from pain only through to loss of deep pain sensation, with prognosis and surgical urgency.
Basis: Modified Frankel / Griffiths 1 to 5 grading
Open calculator
Sending an owner home with instructions?
The owner-facing tools cover toxicity thresholds, feeding amounts, quality of life scoring, vaccination schedules and prevention. Safe to hand out as a link in a discharge email.
Send owners home with the answers, not a printout.
ASK A VET keeps weights, vaccinations, worming, medications and vet notes for every pet in the household, and gives owners certified vet chat between visits — so your discharge instructions have somewhere to live.
The app is free to download. Tracker connectivity, veterinary support and other premium features may require a paid plan. Check the app and product pages for current availability.
The dose you give is your clinical decision.
Check the concentration, every time
The commonest source of error in a drug calculation is not the maths, it is the vial. Concentrations differ between manufacturers, countries and formulations. Read it off the bottle in your hand rather than trusting a default.
Read the working, not just the number
Each result shows the full calculation from the displayed operands, so a transposed weight or a wrong unit is visible rather than buried. If the working does not look like what you expected, stop.
Two-person checks still apply
A calculator does not replace a second pair of eyes on a controlled drug, a transfusion, or a paediatric or exotic dose. The anaesthetic calculator’s cage sheet mode prints a signature line for exactly this reason.
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