How to use the tire pressure calculator
Prepare the values for this calculation
Estimate tire gauge-pressure change from gas-temperature change at constant volume using the ideal-gas relation. Use the formula below to check that it answers your question. Read the input units before transferring figures from a statement, measurement or dataset.
Enter and check each input
- Initial gauge pressure (psi): enter a value at least 0. Use the unit named in the label or selected above. Do not leave this required field blank.
- Initial air temperature (°C): enter a value at least -273.14. Use the unit named in the label or selected above. Do not leave this required field blank.
- New air temperature (°C): enter a value at least -273.14. Use the unit named in the label or selected above. Do not leave this required field blank.
- Atmospheric pressure (psi): enter a value at least 0. Use the unit named in the label or selected above. Do not leave this required field blank.
The input table gives a complete example. Keep units and time periods consistent across related fields.
Calculate and resolve any input error
Choose Calculate after entering the values. Changes also update the answer after a short pause. If an error appears, follow its message, correct the field and calculate again. Reset restores the example values.
Interpret the answer
Check Estimated new gauge pressure first. With the unchanged example inputs, it is 31.609524 psi gauge. Compare the additional metrics with the primary result; each has its own label and unit.
Compare and keep a useful result
For a controlled comparison, keep every other example input unchanged and change Initial gauge pressure (psi) from 35 to 38.5. The resulting Estimated new gauge pressure is 34.870739 psi gauge. This illustrates the equation’s response to that input, rather than a forecast of real events.
Read the chart’s axis labels and data table. A scenario curve changes one stated input while holding the others fixed; it does not add external observations. Use Download graph to save an available chart as a PNG.
Use Copy result or Download CSV to keep the answer. Share tool shares the page address without placing your input values in the URL. Recheck inputs and assumptions before using the result for a decision.
Tire Pressure Calculator formula
P₂,abs=P₁,abs×T₂/T₁; gauge=Pabs−Patm.
Inputs and units
| Input | Format / range | Example |
|---|---|---|
| Initial gauge pressure (psi) | minimum 0 | 35 |
| Initial air temperature (°C) | minimum -273.14 | 20 |
| New air temperature (°C) | minimum -273.14 | 0 |
| Atmospheric pressure (psi) | minimum 0 | 14.6959 |
Worked example
Using the example inputs above, the estimated new gauge pressure is 31.609524 psi gauge.
- Estimated new gauge pressure
- 31.609524 psi gauge
- Initial absolute pressure
- 49.6959 psi abs
Results and assumptions
Ideal-gas, constant-volume estimate only. Always set cold tire pressure to the vehicle/tire manufacturer specification rather than using this estimate as a recommendation.
Fix an input or unexpected result
Initial gauge pressure (psi) is required. Enter initial gauge pressure (psi) using the format and bounds in the input table. Zero and an empty field are different: use zero only if it is allowed and represents your data.
If your answer differs from the example, choose Reset and compare every field, including selected units and options. Check percentage versus decimal entry and whether values describe the same period. Round only the final displayed answer when reproducing the formula.
If a discrepancy remains, report the calculator issue with the page address, non-sensitive example inputs, actual result, expected result and a reference for your calculation.