Cap Table, Equity Dilution, Pre-Seed and Seed funding.
In general, disciplined investors are looking for a targeted return. So you can have all the traction in the world, but if you don't give the investors a valuation where they can participate in significant upside -- they won't be interested (unless it is a strategic investment or an investment which makes them look cool/relevant; however, they are generally in the "return" business). You can perform simple Google search queries to learn about recent and historic seed stage investment amounts and valuations. I found reports that pointed to recent seed stage data, where the median raise is around $1 million and the median valuation is around $6 million; that puts the median equity take around 16.66%. Pitchbook.com is another good source to find stats.
There are about 8 types of funding sources. Angels are one type, and expectations for what angels invest in is quite different than any other funding source. The primary difference is the amount of risk and willingness to participate in companies that are pre-launch. Pretty much only angels will do this. And their risk tolerance as a result is much higher. You will find that angels are motivated by different factors than other investor types, and this dramatically influences what kind of return/exit/timing they expect.
Be mindful that when you say "angel" it is a specific thing, not just an investor. So to answer your question, I'd first check to be sure you mean angel and not another type of investor. It will make a huge difference in their equity expectations.
Capital Angels are truly as different as heaven's Angels! Each will want to create as "safe" an investment as they can.
Investors are not (necessarily) your friends, but they do want you to succeed. If you don't, then their investment has failed.
Look at it from their perspective; no matter how you value your company, they will place their own value on it - as well as measure the risk themselves.
Make sure you offer is not limited to "take it or leave it" but allows for at least two " à la carte " investment options.
Indeed, spend some time working out your MESO for candidate Angels. (MESO: Multiple Equivalent Simultaneous Offers) that you would be happy with - that way everyone can feel like a winner.
PS: Make sure you interview candidate investors - they may not be your friends, but you will want investor partners that are friendly!
Angel investors and VCs are usually buying the future, not the past. As a result, a little (or even no) traction is enough in some circumstances and a lot of traction isn't enough in others.
Valuation isn't the only concern - the amount being raised also matters. Given the same valuation, a company that needs twice as much money has to sell twice as much equity.
It's a complex issue and all of the previous responders have hit on important points. There is no exact answer but there is a likely range of outcomes.
Think of it like selling a house. What's your price point (funding ask)? What shape is the property in (stage of company/product development)? What have other houses in the area sold for (comparable deals)? How attractive is the neighborhood (your sector or market)?
Without specifics it's hard for anyone to say. The broad distribution of percentages is a bell curve with about 10% angel ownership at one end and 50% at the other with the peak of the bell at about 30%.
Guys, great feedback. Thank you! So we are at pre-seed/seed stage, and are awaiting our FCA registration hence. (FinTech company) Until this is finalised we are unable to take revenue. Although our software is ready, we need a Angel Investor to be sympathetic and our obvious concern is that they may take a larger stake as they may look at the "First In" factor which some deem the riskiest. Funding is needed for our compliance and and infrastructure costs (Staff, IT, Broker fees etc). Most VCs would consider us too early, hence a our approach towards Angels or super Angels, with an ask of £250k or £600k at seed.
I noticed in your latest post that you are seeking funding in GBP (Sterling). The following is a bit dated but there's a detailed study of UK angel investor behavior and investment performance at- https://www.nesta.org.uk/sites/default/files/siding_with_the_angels.pdf.
Most Angels want convertible notes - not equity.
It will depend at what stage they come in as investors, seed stage, follow up funding rounds, like series A, etc. Important thing is how much total equity you are diluting or willing to dilute.