Funeral photo slideshow: how many photos, in what order, at what pace

The photos spread themselves evenly across the length of the music, so you never type in seconds. It still helps to know the sum. A four-minute song lasts 240 seconds. A photo is comfortable to look at for 6 to 8 seconds. 240 divided by 8 is 30; 240 divided by 6 is 40. So a four-minute song takes 30 to 40 photos. For three minutes that is roughly 23 to 30, for five minutes roughly 38 to 50.

With fewer photos, the slideshow does not stretch each one indefinitely. A photo is shown for 8 seconds at most; after that the whole set comes round again. Twenty photos on a four-minute song play through twice, at 6 seconds each. Twelve photos play through three times. If you want every picture to appear only once, add photos or shorten the song.

With a lot of photos, each one gets less time. Sixty photos over four minutes is 4 seconds apiece, and they flash past. Once it drops below 6 seconds you see a note on that section. There are three fixes: pick a longer song, add a second piece of music with its own set of photos, or move some pictures to the slideshow that plays while people arrive. A video clip among the photos counts as fixed time. Put a 30-second clip in a four-minute song and 210 seconds remain, enough for 26 to 35 photos.

A screen is landscape; most phone photos are portrait. You decide per section how the slideshow handles that. Fill makes the photo cover the whole screen and trims the edges, which looks good with landscape shots but can cut off a head in a tall portrait. Fit keeps the entire photo visible. The space on either side is then filled with a blurred copy of the same photo, or with a plain colour if you switch the blurred background off. You can also switch it on or off for a single slide.

The pencil on a photo opens the edit screen. There you rotate a picture that is lying on its side, zoom in on a face and shift the crop. You can also add a second photo: smaller, in a corner of the first, in three sizes. That puts a childhood picture and a recent one on the same slide, or two portrait photos side by side. Text such as a name or a year can go on too. A slide with several photos counts as one slide in the timing.

Filling a song with 30 to 40 photos usually takes more than one person's camera roll. Invite family and friends by email as helpers. They get in with their email address and a code, and add photos, videos and music to one shared collection.

HEIC photos from an iPhone, JPEG, PNG, scans and PDFs all work as they are. Nothing needs converting.

You decide which photos from the collection go into which section, and where.

Add the song as your own MP3 file. The length of that track is the length of the sequence, and the photos share the time equally.

If a song is too long for the number of photos, you can shorten it.

Each section shows roughly how many seconds a photo stays on screen, and whether the set repeats. Take five photos out and the figure changes straight away. That lets you steer towards a calm pace without doing sums.

The preview plays the funeral slideshow the way it will run at the service, with the music. You can see whether six seconds suits these pictures and this song, and whether the last photo lands well. If you would rather not hunt for a setting, the assistant in the simple view can change a transition or display mode when you ask in plain words; everything can also be done without it.

Making, watching and changing a photo slideshow for a funeral is free, as often as you like; the free preview carries a light watermark. You pay once, when you download. It runs in the browser on a phone, tablet or laptop, with nothing to install.