Sorry, I don't measure but here is what I use and how I make it.
about 3 medium-large tomatoes
1 large or 2 medium onion
a hand full of fresh cilantro (or a small handful of dried cilantro)
1-2 peppers of your choice (this changes depending how spicy I want it and who will be eating it)
2-4 garlic cloves
some vinegar
salt
sugar
small pinch of cumin
I take 2 of the tomatoes, the half of the onion (sometimes a little more), cilantro, garlic, just over half the peppers, vinegar, salt, sugar and cumin and mix it in a blender (I have a Magic Bullet that works wonders). After that is well mixed/pureed I pour it into a serving dish or Tupperware and chop up the remaining onion, tomato and pepper and toss it in, mix it with a spoon, taste and adjust as needed.
A squeeze of lime juice is yummy in it also.