HydrateWise

Water bottle calculator and refill planner

Find out how many fills you’ll need and when to refill. Use the bottle or glass you already have.

Build a bottle and refill plan

Use your own bottle size to see how many fills you need and space them through the day.

Example target. Enter your own amount to use this as your plan.

When should we space out your refills?

Choose a window that fits around your normal day or shift.

Bottle fills

5 full fillsWith a 500 ml bottle

See refill times

Suggested refill times

07:30 to 22:30
  1. Refill 1Up to 500 ml since you started
  2. Refill 2Up to 500 ml since the previous refill
  3. Refill 3Up to 500 ml since the previous refill
  4. Refill 4Up to 500 ml since the previous refill
  5. End of planUp to 500 ml since the previous refill

Move these times around meals, travel or meetings and drink at a comfortable pace.

Convert litres, ounces, cups and bottles

Check your bottle size or convert a volume from a label. Choose UK or US fluid ounces to match the label, as the two units differ.

Unit definitions

One litre is 1,000 ml. One UK fluid ounce is 28.4130625 ml and one US fluid ounce is 29.5735295625 ml. A metric cup holds 250 ml. A US customary cup holds approximately 236.588 ml. If you use a mug at home, measure how much it actually holds.

What should you carry between refills?

Compare a handheld bottle, belt and vest using the refill stops you know you can reach. This works for a run, walk or hike.

Separate stops with commas or spaces. Leave this blank if there are no confirmed refills. The estimate assumes an even pace and a full refill at each stop. Use the fluid plan you’ve practised.

Use a GPX file for the distance

Your file stays in this browser. Importing updates the distance and keeps any refill stops you’ve entered.

How much each option holds

These are example sizes. Enter what your kit actually holds, including all bottles or flasks you plan to carry.

Planning around aid stations? Use the race planner to put your stops, supplies and timings on one card.

What does your target look like in bottles?

If your target is 2.5 litres, that’s five 500 ml bottles, three 750 ml bottles and another 250 ml, or two and a half 1 litre bottles. Include any tea, coffee, milk or other drinks you’ve already had when working out what’s left.

Move the suggested times around meals, meetings or travel. If you miss a refill, keep drinking at a comfortable pace through the rest of the day.

You can check what’s left after today’s drinks or save a refill routine in the tracker.

Further reading