Billzer: What It Is and Where Receipt Math Starts

Billzer is a free web app for splitting a group's shared expenses. You enter each person's name and what they spent for the group, and it tells everyone who owes whom so you can settle up.

That works well when the question is "who paid for what over the weekend." It does not work out tax and tip on a single restaurant receipt. Below is what billzer does according to its listings, and then one real dinner where the receipt math takes over.

How billzer works for a group's shared costs

Here is what the sources say. They are a launchingnext listing and a Crunchbase profile.

• It runs in the browser. No download, no app install on mobile, no sign-up.
• The listing says it runs without advertising.
• Expenses can be limited to specific people instead of the whole group.
• You can share the results by Facebook, e-mail, WhatsApp and similar services.
• The occasions listed: holidays, road trips, parties, presents, festivals, vacations, weddings, clubs and shared apartments.

Crunchbase's pitch is that it spares groups where everyone paid some of the bills from arguments and wasted time after the fun is over. That is a real problem. Four people each cover a different cost, and someone has to work out the net.

Check that it still loads

The launchingnext page is dated Friday, November 28, 2014. The sources don't confirm the tool's current status. Open the site before you promise your group a link, and have a backup plan if it doesn't load.

Where a spendings-per-person tool stops

A tool like this takes totals. Ana spent $120 on the cabin, Ben spent $60 on groceries. It nets those out. Fine.

A restaurant receipt is different. One check lists every dish, then tax and tip on top. Nobody "spent" a total. Four people ordered different things, and the fees have to be divided too. That math happens before any "who pays whom" step.

Worked example: a four-person dinner. This uses the numbers from EconoGlance's walkthrough.

• Food subtotal: $147.00
• Tax at 8%: $11.76
• Tip at 18% on the pre-tax amount: $26.46
• Total: $185.22

Say Ana had a salad, Ben had a burger and two drinks, Cam had a steak and dessert, and Dee had salmon and wine. The food comes out like this:

Person	Food	Fair share (food × 1.26)	Equal split	Equal split vs fair
Ana	$14.00	$17.64	$46.31	pays $28.67 extra
Ben	$38.00	$47.88	$46.31	owes $1.57 more
Cam	$45.00	$56.70	$46.31	owes $10.39 more
Dee	$50.00	$63.00	$46.31	owes $16.69 more
Total	$147.00	$185.22	$185.24

The multiplier is 1.26 because tax (8%) and tip (18%) add 26% to every dollar of food. Everyone's food gets the same 26% added, so whoever ordered more pays more of both.

Splitting the whole $185.22 four ways is $46.305 a head. In whole cents, two people pay $46.31 and two pay $46.30. The table rounds all four to $46.31, which is why it shows $185.24.

A half-fix: items by person, tax and tip by headcount

Some people split the food by item and then divide tax and tip equally. The fees are $38.22, so that's $9.555 each, or about $9.56.

Ana's salad was $14.00. She'd pay $14.00 plus $9.56, which is $23.56. Her fair share is $17.64. She overpays by $5.92 on a salad.

Dee goes the other way. She pays $59.56 instead of $63.00 and is $3.44 under. The organizer who fronted the bill is the one who quietly absorbs that kind of gap.

A second example: service charge too

Spliit's article shows the same effect with a service charge. Four people have item subtotals of $24, $36, $48 and $72, which is $180.

• Tax: $14.40
• Service charge: $18.00
• Tip: $9.00
• Fees total: $41.40, so the bill is $221.40

Fees add 23% of food. Each person's total is their food times 1.23: $29.52, $44.28, $59.04 and $88.56.

An equal fee split charges everyone $10.35. The person who had $24 of food should pay $5.52 in fees. Equal fees nearly double that. For the full method, see how to split tax and tip fairly.

Tip basics with numbers

Tip on the pre-tax subtotal: subtotal × rate ÷ 100. On a $100 meal with 8% tax, a 20% tip is $20.00 pre-tax or $21.60 post-tax. That's $1.60 apart on one meal.

The US sit-down default is 18–20%. Parties of six or more often get an automatic gratuity of 18–20%, printed as "service charge" or "autograt." Check the receipt before adding a tip. Adding one on top is double tipping.

Rounding so the payer isn't left short

Work in whole cents. A $101.95 bill is 10,195 cents. Across 4 people that's 2,548 cents each with 3 left over. Each person pays $25.48, and three people pay one extra cent.

Rounding down to a friendly number costs the person who paid. A $487.35 bill split eleven ways is $44.30 a head. Ask everyone for a flat $44 and the payer is $3.35 short.

Shared plates and opt-outs

Assign each item to whoever ordered it. Divide tax and tip by each person's subtotal. Split shared plates only among the people who had them.

Lagerland Apps has a bottle example. Sam doesn't drink. By headcount he pays $45.60. By what he consumed he pays $31.20. That's a $14.40 swing for one person. For a walkthrough, see how to split a bill by item.

Trips and rent: where a per-person tally fits

This is the job billzer's description fits best.

• On a multi-day trip, keep a running tally and settle once at the end. It avoids a pile of tiny transfers after every meal. More in how to split expenses on a group trip.
• On a foreign-currency trip, fix one exchange rate in advance and tell everyone. Card issuers may add a foreign-transaction fee, commonly 0–3%.
• For household costs, a couple earning 60,000 and 40,000 could split 60/40. On $2,000 of rent that's $1,200 and $800.

Doing the receipt math

For the dinner above, use the Divvy bill split calculator. It splits a bill evenly or by item, with tip, and it's free on the website. The full calculators page is at /calculators/.

If you're the one who fronted the money and want it on your phone, Divvy bill splitting is an iPhone app that's free to download. Point the camera at the receipt and it reads every line item, the tax and the tip. Tap a name on each item to assign it. Tax and tip are split by each person's share of the items. Each share becomes a Venmo or Cash App request in one tap, and friends open a share link to see what they owe without needing the app or an account.