Fresh Frozen Plasma (FFP) Dose Calculator
Fresh Frozen Plasma (FFP) Dose Calculator
Size an FFP dose from weight at 10, 15 or 20 mL/kg — and check the indication first, because a mildly raised INR in a patient who is not bleeding is the commonest reason FFP is given and the commonest reason it should not be.
Fresh Frozen Plasma (FFP) Dose
Weight × mL/kg70 kg adult at 15 mL/kg
Formula
Conventional adult dose 10–15 mL/kg; several UK services quote 15–20 mL/kg
A standard dose raises each coagulation factor level by roughly 20%
- 10 to 20 mL/kg
- the range actually in print. Australian Lifeblood gives 10–15 mL/kg for adults, NHS guidance 15–20 mL/kg, and US sources 10–20 mL/kg. On a 70 kg adult that is 700 mL against 1,400 mL — a twofold spread, which is why this is a selector and not an average
- roughly 20%
- the expected rise in each factor level after a standard dose. It is an expectation, not a guarantee: donor plasma factor activity is itself only about 70 to 100% of normal, so the achieved rise is frequently smaller than predicted
- thawing time
- 20 to 30 minutes in a water bath, and the clock starts when the laboratory receives the request. Plasma that is needed in an hour has to be asked for now
- what this does not size
- warfarin reversal, which needs a prothrombin complex concentrate; isolated hypofibrinogenaemia, which needs cryoprecipitate or fibrinogen concentrate; and single factor deficiencies, which need the specific concentrate
Worked example
70 kg adult at 15 mL/kg
70 × 15 = 1,050 mL
About three to four adult units of plasma
Expect each factor level to rise by roughly 20%, and be prepared for less
The same adult at 10 mL/kg would receive 700 mL and at 20 mL/kg 1,400 mL — the doses in circulation differ twofold
Request it early: thawing takes 20 to 30 minutes, so plasma ordered when it is needed arrives after it was needed
What FFP is for, and what it is not for
| Situation | FFP? | Why |
|---|---|---|
| Bleeding with a multiple coagulation factor deficiency — major haemorrhage, dilutional coagulopathy, disseminated intravascular coagulation | Yes | This is the indication. FFP replaces all the coagulation factors at once, which is what a multiple deficiency needs |
| Mildly raised INR in a patient who is not bleeding, before a low-risk procedure | No | The commonest inappropriate request. A mildly raised INR does not predict procedural bleeding, and FFP barely moves it — 12 to 15 mL/kg typically shifts an INR of 1.5 hardly at all |
| Abnormal clotting screen in stable liver disease, no bleeding | No | The prolonged PT reflects rebalanced haemostasis, not a bleeding tendency. FFP adds volume, raises portal pressure and can make bleeding worse |
| Warfarin reversal for major bleeding | No | A four-factor prothrombin complex concentrate corrects faster and more completely, in a fraction of the volume. BSH does not recommend FFP for life-threatening bleeding on warfarin |
| Isolated low fibrinogen | No | Cryoprecipitate or fibrinogen concentrate delivers far more fibrinogen per mL |
| Volume expansion, or albumin replacement | No | Crystalloid does the first and albumin the second, without a transfusion exposure |
Volume, units and factor rise for a 70 kg adult
| Dose | Volume | Approximate adult units | Expected factor rise |
|---|---|---|---|
| 10 mL/kg | 700 mL | 2–3 | Around 15%, often less |
| 15 mL/kg | 1,050 mL | 3–4 | Around 20% |
| 20 mL/kg | 1,400 mL | 4–5 | Around 25%, at a substantial volume cost |
The volume is arithmetic; the indication is the decision
Fresh frozen plasma replaces every coagulation factor at once, which makes it the right product for a patient who is bleeding with a multiple factor deficiency and the wrong product for almost everything else. The dose is weight-based, and the per-kilogram figure in print ranges from 10 to 20 mL/kg: Australian Lifeblood gives 10 to 15 mL/kg for adults, several United Kingdom services 15 to 20 mL/kg. On a 70 kg adult that is the difference between 700 mL and 1,400 mL, so this page asks which figure you are working to rather than averaging them into one misleading number.
A standard dose raises each factor level by roughly 20%, and often less than that. The reason is simple and frequently forgotten: donor plasma factor activity is itself only around 70 to 100% of normal, so no volume of plasma can lift a recipient above the plasma it came from. That ceiling is why plasma is a poor tool for correcting a modestly abnormal clotting screen, and why a dose should always be followed by a repeat screen rather than an assumption.
The commonest inappropriate use of FFP is correcting a raised INR in a patient who is not bleeding, before a procedure at low risk of bleeding. A mildly raised INR does not predict procedural haemorrhage, and plasma barely shifts it — an INR of 1.5 is usually still around 1.5 after 15 mL/kg. What the patient reliably receives instead is a litre of fluid, a transfusion exposure, and in liver disease a rise in portal pressure that can make bleeding worse. Transfusion-associated circulatory overload is among the commonest causes of transfusion-related death, and a large plasma dose is one of its classic triggers.
Two practicalities matter more than the decimal places. Plasma has to be thawed, which takes 20 to 30 minutes from the moment the laboratory receives the request, so plasma that will be needed in an hour must be asked for now — in major haemorrhage this is the single commonest cause of delay. And where the problem is narrower than a global coagulopathy, a narrower product is better: a four-factor prothrombin complex concentrate for warfarin reversal, cryoprecipitate or fibrinogen concentrate for hypofibrinogenaemia, a specific concentrate for a single factor deficiency. Every dose here supports a clinician’s prescription rather than replacing it, and blood products are given against a clinical indication, not against a number.
Frequently asked questions
What is the standard dose of fresh frozen plasma?
Ten to 15 mL/kg is the conventional adult dose, with 15 to 20 mL/kg quoted by several UK services. For a 70 kg adult that is roughly 700 to 1,400 mL, or about three to five units. Follow your own protocol’s figure rather than averaging the published ranges.
How much does FFP raise coagulation factor levels?
A standard dose raises each factor level by roughly 20%, and frequently less. Donor plasma factor activity is itself only about 70 to 100% of normal, so plasma cannot lift a recipient above the level of the plasma transfused. Recheck the clotting screen afterwards.
Should FFP be given for a raised INR before a procedure?
Not for a mildly raised INR in a patient who is not bleeding before a low-risk procedure. A mildly raised INR does not predict procedural bleeding, plasma barely corrects it, and the patient is exposed to a volume load and a transfusion for no benefit. This is the commonest inappropriate use of FFP.
How long does FFP take to thaw?
Twenty to 30 minutes in a water bath, timed from when the laboratory receives the request. Plasma needed within the hour has to be requested now — in major haemorrhage, late requesting rather than slow thawing is usually what delays the plasma.
Is FFP the right product for warfarin reversal?
No. For major bleeding on warfarin, BSH recommends a four-factor prothrombin complex concentrate with 5 mg of intravenous vitamin K. PCC corrects the coagulopathy faster and more completely than plasma and in a fraction of the volume; FFP is not recommended for life-threatening bleeding.
Related calculators
References
- Green L, Bolton-Maggs P, Beattie C, et al. British Society of Haematology Guidelines on the spectrum of fresh frozen plasma and cryoprecipitate products: their handling and use in various patient groups in the absence of major bleeding. Br J Haematol. 2018;181(1):54–67.
- Hunt BJ, Allard S, Keeling D, et al. A practical guideline for the haematological management of major haemorrhage. Br J Haematol. 2015;170(6):788–803.
- National Institute for Health and Care Excellence. Blood Transfusion. NICE guideline NG24; 2015.
Medical Disclaimer: The tools and content provided here are for educational and reference purposes only. They are not intended to substitute for professional medical advice, diagnosis, or treatment. Clinical decisions should always be based on the comprehensive assessment of a qualified healthcare professional.