Stroke Volume Calculator
Stroke volume is the blood pumped in a single heartbeat, but one number rarely tells the whole story. This calculator starts from end-diastolic and end-systolic volumes, adds ejection fraction and cardiac output, and offers two more tabs: cardiac index with mean arterial pressure, and a reverse solve for a missing heart rate or stroke volume.
Cardiac index adjusts cardiac output for body size; MAP is the average arterial pressure driving organ perfusion.
Know cardiac output and one of the other two? Solve for the missing one.
This calculator is for education only and is not medical advice. Heart measurements require clinical equipment and interpretation; discuss any concerns or abnormal values with a qualified clinician.
Quick Answer
With an end-diastolic volume of 120 mL, an end-systolic volume of 50 mL and a heart rate of 72 beats per minute, the calculator gives a stroke volume of 70.0 mL per beat, an ejection fraction of 58.3% and a cardiac output of 5.04 litres per minute, all inside the tool's adult resting ranges. The Cardiac index tab turns the same heart into a cardiac index of 2.65, and the Reverse solve tab recovers a heart rate of 70.0 from a cardiac output of 4.9 and a stroke volume of 70.
Key takeaways
- Stroke volume is a subtraction: what the ventricle holds at the end of filling minus what is left after it contracts.
- Ejection fraction is the same beat expressed as a share of the filled ventricle, which is why it travels better between people of different sizes than raw stroke volume.
- Cardiac output needs heart rate. Without it, the first tab gives stroke volume and ejection fraction only, and says so.
- Every range flag in the tool is an adult resting reference, not a diagnosis. A flagged value is a prompt to talk to a clinician, not a label.
Stroke volume
70.0 mL/beat
Ejection fraction
58.3%
Cardiac output
5.04 L/min
Cardiac index
2.65 L/min/m2
- Quick Answer
- How to use the stroke volume calculator
- The three formulas, and the two the second tab adds
- Worked example, checked against the tool
- Normal resting ranges, and why the tool's bands are narrow
- Why one number is not enough: stroke volume versus the full panel
- What competing calculators miss
- Honest limits: what this tool does not do
- Frequently asked questions
- Add This Calculator to Your Website
How to use the stroke volume calculator
Pick a tab, check the pre-filled numbers, and click Calculate or Solve. Results stay hidden until you run a tab, and switching tabs hides the previous results.
- SV / EF / CO: enter EDV and ESV, and heart rate if you want cardiac output. The worked example (120, 50, 72) is pre-filled. Leave heart rate blank and the tool still gives stroke volume and ejection fraction, with a note that cardiac output needs a heart rate.
- Cardiac index + MAP: enter stroke volume, heart rate, systolic and diastolic pressure, height and weight. The worked example (70, 70, 120, 80, 175, 70) is pre-filled. All six fields are required in this tab.
- Reverse solve: choose whether heart rate or stroke volume is missing, enter cardiac output and the known value, then click Solve. The worked example (4.9 litres per minute, known value 70, solving for heart rate) is pre-filled.
- Copy or share each tab's result with the buttons inside that tab's results box.
Invalid inputs are rejected with plain messages: a missing or non-positive EDV, a negative ESV, an ESV at or above EDV, a non-positive heart rate, and in the second tab any missing field or a diastolic pressure at or above systolic. The error that matters most is ESV at or above EDV, because a ventricle cannot eject more blood than it holds, so one of the two numbers is wrong.
The three formulas, and the two the second tab adds
All five formulas describe the same heartbeat from different angles. The first three come from the first tab; cardiac index and mean arterial pressure come from the second.
Ejection fraction (EF) = (SV ÷ EDV) × 100
Cardiac output (CO) = SV × heart rate ÷ 1000 (millilitres to litres)
Cardiac index (CI) = CO ÷ body surface area (BSA)
Mean arterial pressure (MAP) = diastolic + (systolic − diastolic) ÷ 3
Body surface area, Du Bois = 0.007184 × weight0.425 × height0.725 (weight in kg, height in cm)
The division by 1000 in the cardiac output formula is only a unit change: stroke volume is in millilitres per beat and heart rate is in beats per minute, so their product is millilitres per minute, and dividing by 1000 gives litres per minute. The reverse tab runs the same equation backwards: heart rate equals cardiac output times 1000 divided by stroke volume, and stroke volume equals cardiac output times 1000 divided by heart rate.
Worked example, checked against the tool
The first tab's example is EDV 120 mL, ESV 50 mL and heart rate 72 beats per minute. Subtract 50 from 120 for a stroke volume of 70.0 mL per beat. Divide 70 by 120 and multiply by 100 for an ejection fraction of 58.3%. Multiply 70 by 72 and divide by 1000 for a cardiac output of 5.04 litres per minute. All three sit inside the tool's adult resting ranges.
The second tab's example uses stroke volume 70, heart rate 70, blood pressure 120/80, height 175 cm and weight 70 kg. Cardiac output is 70 times 70 divided by 1000, which is 4.90 litres per minute. Mean arterial pressure is 80 plus (120 minus 80) divided by 3, which is 93.33 mmHg. Body surface area by the Du Bois formula is 1.85 m2, and cardiac index is 4.90 divided by 1.85, which is 2.65 litres per minute per square metre. The reverse tab then closes the loop: cardiac output 4.9 with stroke volume 70 gives a heart rate of 70.0 beats per minute, and cardiac output 4.9 with heart rate 70 gives a stroke volume of 70.0 mL per beat.
| Inputs | Tool output | Flag |
|---|---|---|
| EDV 120, ESV 50, HR 72 | SV 70.0 mL/beat; EF 58.3%; CO 5.04 L/min | All within range |
| EDV 120, ESV 50, no HR | SV 70.0 mL/beat; EF 58.3%; CO prompt only | SV and EF within range |
| EDV 100, ESV 60, HR 80 | SV 40.0 mL/beat; EF 40.0%; CO 3.20 L/min | All below range |
| EDV 140, ESV 40, HR 90 | SV 100.0 mL/beat; EF 71.4%; CO 9.00 L/min | SV at top, EF and CO above range |
| CI tab: SV 70, HR 70, 120/80, 175 cm, 70 kg | CO 4.90 L/min; MAP 93.33 mmHg; BSA 1.85 m2; CI 2.65 L/min/m2 | MAP and CI within range |
Check the third row by hand: 100 minus 60 is 40, 40 divided by 100 is 40.0%, and 40 times 80 divided by 1000 is 3.20. Every row above is a real run of the tool.
Normal resting ranges, and why the tool's bands are narrow
The tool flags each result against an adult resting range. Those ranges are reference points for a resting adult, not cutoffs that diagnose anything, and they shift with body size, fitness, age and measurement method (echocardiography versus MRI give different volumes for the same heart).
| Measure | Tool flag range | Wider context |
|---|---|---|
| Stroke volume | 60 to 100 mL/beat | Textbook resting values for a 70 kg adult centre near 70 mL; some physiology sources quote 55 to 100 mL. |
| Ejection fraction | 55 to 70% | Heart failure categories run 50% or more preserved, 41 to 49% mildly reduced, and 40% or less reduced. A normal ejection fraction does not rule out heart failure. |
| Cardiac output | 4.5 to 5.5 L/min | Physiology textbooks quote a wider resting spread, roughly 4.0 to 8.0 L/min. The tool's band is deliberately narrower: it flags the textbook resting centre, not the full spread. |
| Cardiac index | 2.5 to 4.0 L/min/m2 | The standard resting range; below 2.5 suggests output low for body size, above 4.0 suggests a high-output state. |
| Mean arterial pressure | 70 to 100 mmHg | The tool's resting band; sustained values below about 60 mmHg are the usual concern for organ perfusion. |
That narrower cardiac output band is the one place where a reader comparing this tool with a textbook could think the tool is wrong. It is not wrong; it is stricter. A cardiac output of 6.5 litres per minute at rest is inside the textbook spread and will still be flagged above range here, because the tool's reference is the resting centre near 5 litres per minute. The flag is a prompt to think, not a diagnosis, and the article states the wider spread so the flag is never mistaken for one.
Why one number is not enough: stroke volume versus the full panel
Stroke volume alone cannot distinguish two very different hearts. A stroke volume of 70 with a heart rate of 50 gives a cardiac output of 3.50 litres per minute; the same stroke volume with a heart rate of 100 gives 7.00 litres per minute. One of those is a resting athlete, the other could be compensation for something wrong, and stroke volume alone cannot tell them apart.
| What it answers | Stroke volume alone | Full panel |
|---|---|---|
| How much per beat | Yes | Yes |
| How much per minute | No, needs heart rate | Yes, cardiac output |
| Share of the filled ventricle ejected | No, needs EDV as well | Yes, ejection fraction |
| Fair comparison across body sizes | No | Yes, cardiac index via body surface area |
| Pressure driving blood to organs | No | Yes, mean arterial pressure |
That is also why the first tab makes heart rate optional rather than required: a student with only an echocardiogram report (EDV and ESV) can still get stroke volume and ejection fraction, while anyone with a heart rate gets the per-minute picture too. For heart rate itself, the resting heart rate calculator and the maximum heart rate calculator cover the two reference points most often paired with these numbers, and the HEART score calculator covers the emergency chest-pain score that is often confused with these resting measures. Body surface area on its own, without the cardiac panel, is covered by the body surface area calculator.
What competing calculators miss
Most stroke-volume tools on the search results compute one number from EDV and ESV and stop. The gaps below are what the three tabs add.
- Single-number tools (StatGarden and similar): stroke volume and ejection fraction from the same two inputs, well explained, but no cardiac output unless you do the heart-rate multiplication yourself, and no range flagging at all. They teach the subtraction; they do not interpret the result.
- Cardiac-output-first tools (Pearson): the strongest rival, since it solves for cardiac output, stroke volume or heart rate and adds cardiac index and ejection fraction in an advanced mode. Its body surface area helper uses the Mosteller equation, while this tool uses Du Bois, so the two tools' cardiac index figures for the same person can differ by a few percent. Neither is wrong; they are different estimation formulas, and this page states which one it uses.
- Multi-metric tools (Sage Calculator): cardiac output, stroke volume, heart rate, cardiac index and ejection fraction from one menu, but they ask you to supply body surface area directly for cardiac index instead of computing it from height and weight, which is an extra step and an extra chance to mistype.
- Pages with wrong algebra (TrueGeometry's cardiac mechanics page): prints an ejection fraction expression that does not reduce to stroke volume divided by end-diastolic volume. Copying a formula from a page like that is how a correct tool gets rebuilt wrong, which is why this article derives ejection fraction from the subtraction it already performed.
- The gap this page fills: all three tabs in one place, range flags on every output, the Du Bois formula stated in full so the cardiac index can be checked by hand, and a reverse solve for the two cases students actually hit: knowing cardiac output and needing heart rate, or knowing cardiac output and needing stroke volume.
Honest limits: what this tool does not do
This calculator is for education only and is not medical advice. EDV and ESV come from imaging (echocardiogram or MRI) or invasive measurement; you cannot measure them with a cuff or a watch, and guessing them produces a precise-looking answer from invented inputs.
- Ranges are resting adult references. Exercise, pregnancy, childhood and many conditions move every range in the table. A flagged value during exercise, for example, means almost nothing: cardiac output can reach 20 to 25 litres per minute or more in trained athletes at maximal exercise.
- The tool does not label heart failure categories. It flags ejection fraction only as below, within or above 55 to 70%. The heart failure categories in the ranges table (preserved 50% or more, mildly reduced 41 to 49%, reduced 40% or less) are context from clinical guidance, not tool output, and a clinician reads them against symptoms, images and other tests.
- Du Bois is an estimate. Body surface area from height and weight is an approximation, and different formulas (Du Bois, Mosteller, Haycock) disagree by a few percent. Cardiac index inherits that uncertainty, so treat the second decimal as arithmetic, not precision.
- The first tab's Reset only resets the first tab. Each tab has its own Reset button, restoring that tab's worked-example values and hiding that tab's results. Switching tabs does not clear another tab's inputs.
Frequently asked questions
Subtract end-systolic volume from end-diastolic volume. For EDV 120 mL and ESV 50 mL, stroke volume is 120 minus 50, which equals 70 mL per beat.
Ejection fraction is stroke volume divided by end-diastolic volume, times 100. For SV 70 mL and EDV 120 mL, it is 70 divided by 120 times 100, which equals 58.3%. The tool flags 55 to 70% as the normal resting range. Clinical guidance groups heart failure by ejection fraction as 50% or more preserved, 41 to 49% mildly reduced, and 40% or less reduced, but a normal ejection fraction does not rule out heart failure.
Cardiac output is the blood pumped per minute: stroke volume times heart rate, divided by 1000 to convert millilitres to litres. For SV 70 mL and heart rate 72 beats per minute, cardiac output is 70 times 72 divided by 1000, which equals 5.04 litres per minute. The tool flags 4.5 to 5.5 litres per minute as its resting range, which is narrower than the wider textbook spread of roughly 4.0 to 8.0 litres per minute.
Cardiac index is cardiac output divided by body surface area, so it compares hearts across body sizes. Body surface area by Du Bois is 0.007184 times weight in kilograms to the power 0.425 times height in centimetres to the power 0.725. For SV 70, heart rate 70, height 175 cm and weight 70 kg, cardiac output is 4.90 litres per minute, body surface area is 1.85 square metres, and cardiac index is 2.65 litres per minute per square metre, inside the normal resting range of 2.5 to 4.0.
Mean arterial pressure is diastolic pressure plus one third of the pulse pressure: MAP equals diastolic plus (systolic minus diastolic) divided by 3. For blood pressure 120/80, that is 80 plus 40 divided by 3, which equals 93.33 mmHg. The tool flags 70 to 100 mmHg as the normal resting range.
Because the ventricle cannot eject more blood than it contains. End-diastolic volume is what the ventricle holds at the end of filling, and end-systolic volume is what is left after contraction, so the second number must be smaller. If your numbers violate this, the tool shows an error and one of the two numbers is wrong.
Use the Reverse solve tab. Choose what is missing, enter cardiac output and the known value, then click Solve. With cardiac output 4.9 litres per minute and stroke volume 70 mL, heart rate is 4.9 times 1000 divided by 70, which equals 70.0 beats per minute. With cardiac output 4.9 and heart rate 70, stroke volume is 4.9 times 1000 divided by 70, which equals 70.0 mL per beat.
Yes, substantially. Stroke volume rises and heart rate rises, so cardiac output can reach 20 to 25 litres per minute or more in trained athletes during maximal exercise. The ranges in this tool are resting references, so do not apply them to exercise values.
No. This calculator is for education only and is not medical advice. Heart measurements require clinical equipment and interpretation, and out-of-range results should be discussed with a qualified clinician rather than acted on from a web calculation.
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References
- StatPearls, NCBI Bookshelf. Physiology, Cardiac Preload (stroke volume as end-diastolic volume minus end-systolic volume on the pressure-volume loop; ejection fraction as EDV minus ESV over EDV). Accessed October 24, 2026.
- StatPearls, NCBI Bookshelf. Physiology, Left Ventricular Function (cardiac output as heart rate times stroke volume; stroke volume as EDV minus ESV; left ventricular ejection fraction definition). Accessed October 24, 2026.
- OpenStax, Anatomy and Physiology 2e. Cardiac Physiology (resting stroke volume roughly 55 to 100 mL, resting cardiac output roughly 4.0 to 8.0 litres per minute, ejection fraction roughly 55 to 70% with a mean of 58%). Accessed October 24, 2026.
- NewYork-Presbyterian Health Matters. What Ejection Fraction Tells You About Your Heart Health, and What It Does Not (normal ejection fraction approximately 55 to 70%; preserved 50% or more, mildly reduced 41 to 49%, reduced 40% or less). Accessed October 24, 2026.
- British Heart Foundation. Heart Failure: Causes, Symptoms and Treatment (ejection fraction classes as BHF states them: preserved 50% or more, mildly reduced 40 to 49%, reduced 40% or less; the article's ranges table uses 41 to 49% for mildly reduced, following the other cited guidance). Accessed October 24, 2026.
- Harvard Health. Measuring Ejection Fraction (normal ejection fraction about 55 to 70%; borderline low around 40 to 50%; below 40% means the heart is struggling to supply the body). Accessed October 24, 2026.
- StatPearls. Body Surface Area (Du Bois and Du Bois formula: BSA equals 0.007184 times height in centimetres to the power 0.725 times weight in kilograms to the power 0.425; BSA used to calculate cardiac index). Accessed October 24, 2026.
- StatPearls. Physiology, Cardiac Index (cardiac index as cardiac output divided by body surface area, equal to heart rate times stroke volume divided by BSA). Accessed October 24, 2026.
- Cleveland Clinic. How To Take Blood Pressure Measurements (systolic and diastolic definitions in mmHg; normal 120/80 mmHg or lower; elevated and stage 1 and 2 bands). Accessed October 24, 2026.
- The Tech Edvocate. How to Calculate Cardiac Index (cardiac output as stroke volume times heart rate; Du Bois body surface area formula; cardiac index as cardiac output divided by BSA; normal cardiac index 2.5 to 4 litres per minute per square metre). Accessed October 24, 2026.