A list of landmass and ocean at least 1/2 billion km^2.

53 under 56% is 53 m. km^2 land

44 over 43% is 44 m. km^2 ocean, 97 total 

58 over 52% is 58 m. km^2 ocean, 165 total

50 under 50% is 50 m. km^2 land, 215 total

39 over 35% is 39 m. km^2 ocean, 254 total

50 over 39% is 50 m. km^2 ocean, 304 total 

45 under 46% is 45 m. km^2 land, 349 total

41 under 95% is 41 m. km^2 land, 390 total

56 over 38% is 56 m. km^2 ocean, 446 total

43 under 79% is 43 m. km^2 land, 489 total

33 under 100% is 33 m. km^2 land, 522 total

53+50+45+41+43+33

103+86+76

189+76

265 land out of 522, 257 ocean out of 522

This is more than half land; I would like to run a Monte Carlo simulation of this, to see what we are likely have, land and hydrographic ratio.

I went old school and bought a copy of Mongoose Traveller. I lurked in the back and rolled up a navy engineer, a lieutenant who I had leave service at thirty with 25kCr, two shares in a ship and a TAS membership. He also has a contact in a rival interstellar navy, the Essjoan Star Navy. I really need to roll up a homeworld and the Essjoan HW, Essjoha.

Main character - Two d% rolls of 61 and 36, which is a 36 year old woman. There is a side kick, 46 and 40, a 40 year old female. Are they related? 43 over 38%, no. Are they romantically involved? 46 over 32%, no.

No romance, no family relationship... wait, are they in laws? 43 over 40%, they are nothing to each other! 8-P

The 36 year old woman helped the forty year old with her divorce and keeping her kids.

Quick and dirty world building...

Is the blob landmass or ocean? We need a reasonable target hydrographic ratio and the land ratio, to use in finding a random world map filling procedure.

One way is to choose a target number, the lesser of two d% rolls. If less than, it's landmass, if greeter, ocean. Landmass is less likely and trends smaller, but we could still see vast continents or tiny oceans 

50 and 41, so a 41% chance of landmass. 36, a 36 m. km^2 continent half again the size of North America.

52 and 39, so 39% chance of land; 46, 46 m  km^2 of ocean adjacent to the continent.

46/82 ocean, HR roughly 56% so far. More than four hundred short of the half billion. On average it takes ten iterations to get to 500 m. km^2.

I have consistently made world mapping too hard. Quick and dirty world build my land and sea with d% rolls. Each number is the area of each bit of landmass or ocean. It's ocean if the # is greater than 29% or whatever your target land ratio is. Blob zero is at tht north pole, blob one is adjacent. This is quick and dirty, remember? 8-P

43, polar ocean 

65, adjacent ocean, may merge, 108 m. km^2 total, 0% land...

41, more ocean, 149 total

28, landmass!!! 28/177 is 15.82% land

Continue until we have an earth sized world, setting a default of ~500 m. km^2 surface area.

So far we have roughly the northern third of the world, the three ocean blobs would be a little more than down to ~30 degrees north latitude.

How about a situation? 

40, 25, a 25 year old woman rescues... 56, 24, a 24 year old woman. From drowning? 40 under 56%, yes, a flash flood, younger woman drove into deeper water than they expected and the car went floating.

Romantic? 50 over 44%, no, just a little hero worship. 25 gets 24 out of her car and onto dry ground like a wet rat...

Kitty, for Catherine, and Fanny, real name Sarah. Kitty is a paramedic and firefighter. Fanny is a dental hygienist.

Catherine rescues Sarah and Sarah sets out to return to favor as best she can, meddling in her life in well meaning ways...

41 over 30, a 30 year old woman, Sarah's older sister.

29 over 24, a 24 year old woman, Sarah's twin sister.

38 over 26, a 26 year old man, her middle brother.

Fanny/Sarah tries to play match maker, a little confused as to which way Kitty swings. Anna, Bruce and Deborah...

Mass of aliens: 2 d% rolls, 46 and 55, normal range of 46 to 55 kg, or take the higher # and use +/-46%? That's a range of 30 to 80 kg, 66 to 176 #s, average of 121 #s.

Bilateral or radial symmetry? 60% chance bilateral, 44 is a yes. Bilateral evolved from 'fish'. That last is just a judgement call, crawled up into the mud with more that two pairs of legs? 36 under... 36%? Interesting. Yes. More than three pairs? 51 over 44%, so no, three pairs, a centauroid?