To convert barrels per day to US gallons per day, multiply by 42.00000866. That factor is the whole relationship: both units measure volumetric flow, so the conversion is a proportion with no offset and no substance-specific constant.
The rating unit for reverse-osmosis membranes and water demand. The unit oil production is reported in worldwide.
Standard versus actual volume. Gas flow in CFM depends on pressure and temperature, which is why compressor ratings say SCFM and specify the reference conditions. Converting the number is exact; comparing two ratings measured at different conditions is not. Two tables follow: rounded steps for quick lookup, and a set of real reference quantities converted into US gallons per day, which is usually more useful than the bare number.
The formula
barrels per day- The amount you are converting, in barrels per day
42.0000086615- The exact number of US gallons per day in one barrel per day
US gallons per day- The converted result
How it works, step by step
- Enter the value in barrels per day.
- It is multiplied by 42.0000086615, the exact factor between the two units.
- The answer is shown in US gallons per day, with the reverse conversion beneath it.
- Check the reference table if you want a figure of comparable size.
Worked examples
A garden hose: 163 bbl/d in US gallons per day
A garden hose comes to about 163 bbl/d. Multiplying by the factor: 163 × 42 = 6846 GPD. Dividing the answer back by 42 returns the figure you started with, which is the quickest way to check you have the factor the right way up.
A shower head: 87 bbl/d in US gallons per day
Take a shower head, roughly 87 bbl/d. The conversion is a single multiplication — 87 × 42 — giving 3654 GPD. Because the relationship is proportional, doubling the input doubles the answer to 7308 GPD.
How to read your score
Frequently asked questions
How many US gallons per day are in one barrel per day?
Exactly 42.0000086615. Every figure on this page is that one number multiplied by your input, so the only rounding is at the display step.
What is the formula to convert barrels per day to US gallons per day?
US gallons per day = barrels per day × 42.0000086615. Reversed, barrels per day = US gallons per day ÷ 42.0000086615, which is the same as multiplying by 0.0238095188994.
Which is the bigger unit, the barrel per day or the US gallon per day?
The barrel per day. One barrel per day equals 42 US gallons per day.
What does this quantity actually measure?
Both units measure volumetric flow. That is why a single factor is enough: there is no temperature offset and no material property involved, unlike conversions that cross between different quantities.
What is a barrel per day?
The unit oil production is reported in worldwide.
What is a US gallon per day?
The rating unit for reverse-osmosis membranes and water demand.
Why does my answer differ from another converter?
Almost always because the other tool rounded the factor before multiplying. This page keeps full double precision through the calculation and rounds only for display, and it prints the factor it used so you can see where any difference came from.
Is there a quick way to do bbl/d to GPD in my head?
Plenty of people do this in their head: multiply by 42 instead of using the exact factor 42.00000866. At 100 that shortcut gives 4200 US gallons per day, off by 0.0008661 US gallons per day or about 0.00%. Fine for a rough estimate, not fine for anything you are cutting to size or dosing.
Barrels Per Day to US gallons per day reference tables
| Barrels Per Day | Us Gallons Per Day |
|---|---|
| 0.5 bbl/d | 21 GPD |
| 1 bbl/d | 42 GPD |
| 2 bbl/d | 84 GPD |
| 3 bbl/d | 126 GPD |
| 5 bbl/d | 210 GPD |
| 10 bbl/d | 420 GPD |
| 20 bbl/d | 840 GPD |
| 25 bbl/d | 1050 GPD |
| 50 bbl/d | 2100 GPD |
| 75 bbl/d | 3150 GPD |
| 100 bbl/d | 4200 GPD |
| 250 bbl/d | 10,500 GPD |
| 500 bbl/d | 21,000 GPD |
| 1000 bbl/d | 42,000 GPD |
| 5000 bbl/d | 210,000 GPD |
Exact factor: 1 barrel per day = 42.0000086615 US gallons per day.
| Quantity | bbl/d | GPD |
|---|---|---|
| A dripping tap | 0.05434 bbl/d | 2.282 GPD |
| A bathroom tap | 54.34 bbl/d | 2282 GPD |
| A shower head | 86.95 bbl/d | 3652 GPD |
| A garden hose | 163 bbl/d | 6847 GPD |
| A fire hydrant | 3.261e+04 bbl/d | 1.369e+06 GPD |
| The Thames at London | 3.532e+07 bbl/d | 1.484e+09 GPD |
Published reference values, converted with the same factor this page uses.