There are three ways to record how much you pass for a bladder diary: measure it in a jug, catch it in a collection hat that sits under the toilet seat, or, when neither is possible, keep the time and tick the trip as not measured. Clinics accept all three. What they need is every trip with its time; the volume comes second.

What the diary is asking for

“Output” in a diary is the volume of each trip to the toilet, in millilitres or fluid ounces, written next to the time. Voided volumes and their times are the core of the frequency–volume chart as the International Continence Society defines it, and of every diary format that has been studied since.1,2 Clinic forms lay it out differently: the BAUS input/output chart has an OUT column against each hour,3 the Urology Care Foundation diary asks “how much urine?” for each trip,4 and our printable template has a Passed column marked “ml or ✓”. Every one of them accepts a tick when you couldn’t measure. None of them asks whether your numbers are normal; your clinician reads the pattern, you supply the record. How the whole diary fits together is in how to keep a bladder diary.

Way 1: a measuring jug

Any plastic jug marked in millilitres will do.5 BAUS suggests one that holds at least 500 ml;3 a pharmacy or a supermarket kitchen aisle has them. Keep it for the diary only, and keep it by the toilet.

Sit on the toilet and hold the jug in the bowl. The Sussex physiotherapy chart is specific about this: sit properly, don’t hover or squat above the seat, because sitting lets the pelvic floor relax and you empty more completely.6 Men can stand and use the jug directly.

Put the jug on a flat surface and read the level at eye level, then write the number down before you do anything else. Round to the nearest line on the jug; the scale is not finer than that, and neither is the diary. Pour it away and rinse the jug with water.

Way 2: a collection hat

A collection hat is a plastic bowl with a wide brim that sits under the toilet seat, with a scale printed inside in millilitres and fluid ounces. Clinics often hand one out with the diary.4 If yours didn’t, pharmacies and online shops sell them as a urine collection hat or specimen collection hat.

Put it under the seat towards the front of the bowl, sit as usual, then read the level, write it down, empty the hat into the toilet and rinse it.4 Nothing to hold, which is why it is the easiest option at night and when you are in a hurry.

Way 3: when you can’t measure

At work, in a shop, in the middle of the night when you’re half asleep: keep the time and tick the trip. The NHS chart and the BAUS chart both say exactly that, a tick in the urine column;3,5 our template has a ✓ in the Passed column; in the app it is the Not measured button. The trip still counts for how often you go and for the night count. It just doesn’t add to the volume total.

An estimate is also allowed. If you have measured yourself for a day or two and know what a usual trip looks like in your jug, write your estimate and mark it “approx.” When in doubt, tick.

What spoils the diary is a trip that isn’t written down at all. A ticked line with a time tells your clinician something; an empty line tells them nothing.

Millilitres or fluid ounces: which unit for a bladder diary?

Use one unit for the whole diary, the one printed on your clinic’s form. If you need to convert:

  • 1 US fluid ounce is about 30 ml (29.6 ml exactly).
  • 1 cup, or 8 fluid ounces, is about 240 ml.
  • 100 ml is about 3.4 fluid ounces; a 500 ml bottle is about 17.

Our template comes in both: A4 sheets in millilitres, US Letter sheets in fluid ounces. In the app the unit is a setting, and the report uses whichever you chose.

The drinks side

Measuring what you drink is easier: the amount is usually printed on the container. Common sizes, the same ones our template and the app use as presets: a cup 200–250 ml, a glass 250 ml, a can 330 ml, a small bottle 500 ml. The Urology Care Foundation lists the US equivalents: an 8 oz cup, a 12 oz can, a 20 oz bottle.4

For your own mug, glass or water bottle, measure it once with the jug, then use the same cup for the diary days. Both BAUS and the Sussex chart suggest it.3,6 Write the type of drink too, tea, coffee, water, beer; clinics ask for it.3,7

At night

Before bed, put the hat in place or leave the jug by the toilet, and leave a small light on. Time first, volume second: if measuring isn’t happening at three in the morning, tick and go back to sleep.

Write down when you went to bed and when you got up. BAUS asks for two lines across the day’s column, the NHS chart asks for BED and WOKE in the time column,3,5 and our template has a box for each at the top of every page. That is how night trips are counted.

After surgery or with a catheter

On a ward the same record is called an intake and output chart or a fluid balance chart, and nurses fill it in. If you go home with a catheter, your nurse will show you how to read and empty the bag; the diary line is the same, time and amount. Follow their instructions about what to record and how often.

Keep it clean and simple

Use the jug or hat for this and nothing else. Rinse it after every use,4 wash it with soap once a day, wash your hands. Keep it where you use it, not in a cupboard. And write the number the moment you have it: a volume remembered two hours later is a guess.