School fees do not include a lot of the extras, like uniforms, shoes, any out of class activities, transportation, etc. Schooling only gets more expensive as the child progresses through the grades. Internet and phone probably about 200 min/month depending on bandwidth and usage.

If you like a drink now and again, that's expensive too - the 5* hotels are about 40 - 50QR per beer more expensive per glass of wine. You can get a license with your employer's OK for a refundable deposit of QR1000. Case of 24 beer about QR150 on average.

As for cheap international schools, you get what you pay for. And anyone can call themselves an international school, that doesn't mean they have qualified or competent teachers or they may not follow a curriculum that will be what you want for your children.

So erring on the low side, schooling will be a minimum of 5000QR each month, transportation for school about 3000 each month other school expenses say 500/month. So for the children alone for school and related expenses maybe 8500QR.

Food for 5 people - probably closer to 2000/month not including any treats at restaurants.

Petrol - erring on the high side 500/month

You get vacation tickets, how about where you will vacation? Hotels/meals etc can add up quickly for a family.

Clothing for you and your spouse - any incidentals - kitchen appliances etc that may not be provided by the employer, household cleaners/detergents/toilet paper/etc., etc.

It all adds up. For the last paragraph, do a quick calculation of what these things cost you monthly at home, then double it for a conservative estimate of what it might cost you here.

HTH