How to use
- Enter the number of people and how many hours you want to plan for. Use moving hours plus the time you will actually be away from a refill.
- Enter a rate per person per hour. Pick liters or US fluid ounces. One US fluid ounce is 0.0295735 liters.
- Optionally enter the capacity of one bottle in liters. The result then includes how many of those bottles the total represents.
- Press Calculate. Change the rate and calculate again if the day is hotter or the work is harder. The page will not change the rate for you.
How it's calculated
Group total = liters per person × people
Bottles = group total ÷ bottle size
The only science in the form is the unit conversion. A US fluid ounce is 0.0295735295625 liters. The rate itself is an assumption you are willing to plan around. Land managers and outdoor schools sometimes suggest planning ranges for temperate days and higher ranges for heat; those ranges are not copied into this form as a default, because applying someone else’s range without the conditions they stated is how a planner becomes a fake precision.
Heat index, which is one reason a rate might go up, is calculated from temperature and humidity on the ClearQuip wind chill and heat index calculator. Once you know the liters, weigh them on the pack weight calculator.
Worked example
If you choose 0.5 liters per person per hour for 6 hours and 2 people, each person is planned at 3.0 liters and the group total is 6.0 liters. That is 6 ÷ 1 = 6 one-liter bottles, or about 203 US fluid ounces because 6 ÷ 0.0295735 ≈ 203. The 0.5 liter figure is an example input, not a recommendation stored in the page.
Assumptions and sources
The US fluid ounce conversion is the international definition, 1 fl oz = 0.0295735295625 L. The calculator does not add a reserve, a cooking allowance, or a cache. Add those hours or that extra volume into the numbers you type. It does not know the weather. A worked example that uses 0.5 L per hour is labeled as your choice for that example, not as HikeSpan’s required rate.
FAQ
Why is there no default rate?
Because a hidden default would look like advice. Type the rate you want to plan with, and the math will scale it.
How do I convert fluid ounces to liters?
Multiply US fluid ounces by 0.0295735. Or select fluid ounces in the unit menu and let the page convert.
Does this include water for cooking?
Only if you increase the rate or the hours so the total includes it. There is no separate cooking field.
Is more always safer?
Carrying more water has a weight cost and still may not match thirst, heat, or illness. This page only scales the rate you entered.