The average cost of sending a child to a state school in England is more than £736 a year, a report says.
Parents face many costs in sending children to school
The Department for Education and Skills study found parents paying for things such as uniforms, food and travel.
The survey by BMRB of 1,500 people in England found the total annual average cost was £563.15 for primary schools and £948.11 for secondary pupils.
The Child Poverty Action Group is calling for extra help with expenses for low-income households.
Chief executive Kate Green said: "The real costs of education are a day-to-day pressure for many parents from low-income households and the report must be a springboard for government action."
According to the DfES report, The Cost of Schooling, parents spent £316.20 - or £1.66 a day - on meals.
EXAMPLES OF AVERAGE COSTS
Residential trips: £186.72
PE kit: £78.47
School funds: £25.32
School photos: £15.71
Source: DfES report The Cost of Schooling
Ms Green said: "We know that up to 350,000 children each year are not claiming their free school meals for a number of reasons including fear of stigma and bullying.
"But many of these children's families cannot afford an extra £316 a year and so they will go without."
More than one in five parents (21%) said their child used public transport or taxis to and from school, and two thirds of these paid the costs themselves - the average being £7.29 a week or about £284 a year.
The average amount spent on PE kit was £78.47, with another £224.69 going towards school uniforms.
Meanwhile, £186.72 went on residential trips, £15.71 on school photographs and £25.32 on school funds.
Ms Green called the findings a "wake-up call", adding that if nothing was done, many pupils would "simply have to go without".
However, 90% of the parents responding to the survey said school costs were not too expensive.
A DfES spokesman said the government was investing a record amount in schools, with funding per pupil up 45%, or £1,300, since 1997.
He added: "Costs associated with schooling are mostly a matter for individual schools and local education authorities.
"Support is available for parents on low income, with free school meals, free transport for pupils and local schemes to assist with the cost of school trips."
The Liberal Democrat spokesman, Phil Willis, said parents should brace themselves for a dramatic increase in the cost of sending their children to school under Labour.
"If the government goes ahead with the unpopular School Transport Bill it will cost families an additional £400 a year per child in travel costs," he said.
He called this "a stealth tax on families".
A recent survey of 500 parents by the online bank Egg found parents spent an average of £2,916 a year on bringing up a daughter and £2,790 on a son.